Patent Application
20160258160
The technical field relates to structural members such as beams and columns. More particularly, it relates to composite structural members including an outer shell defining an inner space at least partially filled with concrete. It also relates to a method for producing same. Furthermore, it relates to connecting assemblies for connecting at least two mutually perpendicular composite structural members.
Structural members for infrastructure, such as beams and columns, are typically made from steel and/or concrete. However, over the years, both have shown several drawbacks. For instance, corrosion is a problem for steel structural supports especially in corrosive environments. Concrete structural members are also subjected to deterioration of their long-term durability and their structural durability. Permeability of the exposed concrete by water can cause the concrete to deteriorate over time. For example, in northern climate areas that are subjected to the changeable weather conditions due to winter and summer, moisture trapped and frozen in concrete during the winter can expand during summer and cracks the concrete structural members. Furthermore, corrosion is known to occur to the reinforcing steel bars used inside reinforced concrete (RC) structural members.
Over the last years, the use of an external tube, as an outer shell, filled with concrete has been found to isolate and waterproof exposed concrete structural applications, as well as remove the need for formwork and formwork removal. However, these structural members are typically relatively heavy, which may increase transportation and installation costs substantially.
It is therefore an aim of the present invention to address the above mentioned issues.
According to a general aspect, there is provided a structural member having a longitudinal axis. The structural member comprises: an exterior shell member defining an elongated channel with an inner surface; an interior shell member having an outer surface and defining an inner channel, the interior shell member being inserted in the elongated channel of the exterior shell member and extending longitudinally therein; and concrete between the interior shell member and the exterior shell member with at least one reinforcement bar including a longitudinally extending section extending along the longitudinal axis and between the interior shell member and the exterior shell member and being disconnected from the inner surface of the exterior shell member and from the outer surface of the interior shell member.
In an embodiment, each one of the interior shell member and the exterior shell member comprises two opposed ends, the ends of the inner shell member being spaced-apart inwardly along the longitudinal axis from a corresponding end of the exterior shell member. The ends of the interior shell member, spaced-apart inwardly along the longitudinal axis from the corresponding end of the exterior shell member, can be covered with the concrete.
In an embodiment, the interior shell member has a length along the longitudinal axis shorter than a length of the exterior shell member along the longitudinal axis, the interior shell member being contained in the exterior shell member and surrounded by the concrete. The structural member can comprise at least one interior end spacing filled with concrete, the at least one interior end spacing being defined between an end of the interior shell member spaced-apart inwardly along the longitudinal axis from a corresponding end of the exterior shell member, and a length of the at least one interior end spacing being at least 10% of a length of the exterior shell member. The at least one reinforcement bar can comprise a transversally extending section extending from the longitudinally extending section into a respective one of the at least one interior end spacing, the longitudinally and transversally extending sections being embedded in the concrete. The at least one reinforcement bar can further comprise a second longitudinally extending section extending from the transversally extending section between the exterior shell member and the interior shell member.
In an embodiment, the at least one reinforcement bar comprises a plurality of reinforcement bars connected together to define a reinforced concrete armature embedded in the concrete and spaced-apart from the outer surface of the interior shell member and the inner surface of the exterior shell member.
In an embodiment, the longitudinally extending section of the at least one reinforcement bar extends past opposed ends of the interior shell member.
In an embodiment, the at least one reinforcement bar comprises a hook at a free end thereof.
In an embodiment, the inner channel of the interior shell member is at least partially hollow. Between about 30% and about 80% of a volume of the structural member can be hollow. The inner channel of the interior shell member can comprise opposed end sections filled with concrete and wherein each one of the opposed end sections can have a length and the length of each one of the opposed end sections can be about 5% to 20% of a length of the interior shell member.
In an embodiment, the at least one reinforcement bar is spaced apart from the inner surface of the exterior shell member and the outer surface of the interior shell member.
In an embodiment, the at least one reinforcement bar is embedded in the concrete.
In an embodiment, the structural member is an elongated beam and a central longitudinal axis of the interior shell member is decentered on a tension side of the elongated beam.
In an embodiment, the structural member is an elongated beam and the longitudinally extending section of the at least one reinforcement bar extends on a tension side of the elongated beam.
In an embodiment, at least one of the exterior shell member and the interior shell member comprises fiber reinforced polymer.
In an embodiment, a ratio of the diameters of the interior shell member and the exterior shell member is between about 0.2 and about 0.8.
In an embodiment, a length of the interior shell member is between about 30% to about 80% the length of the exterior shell member.
In an embodiment, at least one of the inner surface of the exterior shell member and the outer surface of the interior shell member comprises at least one of a concrete adherence enhancing coating and a plurality of concrete adherence enhancer.
In an embodiment, at least one of the inner surface of the exterior shell member and the outer surface of the interior shell member comprises a polymeric coating including abrasive particles.
In an embodiment, at least one of the inner surface of the exterior shell member and the outer surface of the interior shell member comprises a plurality of narrow grooves defined therein.
In an embodiment, at least one of the inner surface of the exterior shell member and the outer surface of the interior shell member comprises a plurality of spaced-apart pins protruding from a respective one of the inner surface of the exterior shell member and the outer surface of the interior shell member.
In an embodiment, at least one of the exterior shell member and the interior shell member comprises helicoidal fiber windings adjacent to a respective one of the inner surface and the outer surface.
According to another general aspect, there is provided a structural member having a longitudinal axis. The structural member comprises: an exterior shell member defining an elongated channel with an inner surface; an interior shell member having an outer surface and defining an inner channel, inserted in the elongated channel of the exterior shell member and extending longitudinally therein and defining an inter-shell spacing therebetween; and concrete filling the inter-shell spacing and including at least one reinforcement bar having a longitudinally extending section extending in the inter-shell spacing and being disconnected from the inner surface of the exterior shell member and from the outer surface of the interior shell member.
In an embodiment, each one of the interior shell member and the exterior shell member comprises two opposed ends, the ends of the inner shell member being spaced-apart inwardly along the longitudinal axis from a corresponding end of the exterior shell member. The ends of the interior shell member, spaced-apart inwardly along the longitudinal axis from the corresponding end of the exterior shell member, can be covered with the concrete.
In an embodiment, the interior shell member has a length along the longitudinal axis shorter than a length of the exterior shell member along the longitudinal axis, the interior shell member being contained in the exterior shell member and surrounded by the concrete. The structural member can further comprise at least one interior end spacing filled with concrete, defined between an end of the interior shell member spaced-apart inwardly along the longitudinal axis from a corresponding end of the exterior shell member, and a length of the at least one interior end spacing being at least 10% of a length of the exterior shell member. The at least one reinforcement bar can comprise a transversally extending section extending from the longitudinally extending section into a respective one of the at least one interior end spacing, the longitudinally and transversally extending sections being embedded in the concrete. The at least one reinforcement bar further can comprise a second longitudinally extending section extending from the transversally extending section in the inter-shell spacing.
In an embodiment, the at least one reinforcement bar comprises a plurality of reinforcement bars connected together to define a reinforced concrete armature embedded in the concrete and spaced-apart from the outer surface of the interior shell member and the inner surface of the exterior shell member.
In an embodiment, the at least one reinforcement bar comprises a hook at a free end thereof.
In an embodiment, the longitudinally extending section of the at least one reinforcement bar extends past opposed ends of the interior shell member.
In an embodiment, the inner channel of the interior shell member is hollow. Between about 30% and about 80% of a volume of the structural member can be hollow. The inner channel of the interior shell member can comprise opposed end sections filled with concrete and wherein each one of the opposed end sections can have a length and a length of each one of the opposed end sections can be about 5% to 20% of the length of the interior shell member.
In an embodiment, the at least one reinforcement bar is spaced apart from the inner surface of the exterior shell member and the outer surface of the interior shell member.
In an embodiment, the at least one reinforcement bar is embedded in the concrete.
In an embodiment, the structural member is an elongated beam and a central longitudinal axis of the interior shell member is decentered on a tension side of the elongated beam.
In an embodiment, the structural member is an elongated beam and the longitudinally extending section of the at least one reinforcement bar extends on a tension side of the elongated beam.
In an embodiment, at least one of the exterior shell member and the interior shell member comprises fiber reinforced polymer.
In an embodiment, a ratio of the diameters of the interior shell member and the exterior shell member is between about 0.2 and about 0.8.
In an embodiment, a length of the interior shell member is between about 30% to about 80% the length of the exterior shell member.
In an embodiment, at least one of the inner surface of the exterior shell member and the outer surface of the interior shell member comprises at least one of a concrete adherence enhancing coating and a plurality of concrete adherence enhancer.
In an embodiment, at least one of the inner surface of the exterior shell member and the outer surface of the interior shell member comprises a polymeric coating including abrasive particles.
In an embodiment, at least one of the inner surface of the exterior shell member and the outer surface of the interior shell member comprises a plurality of narrow grooves defined therein.
In an embodiment, at least one of the inner surface of the exterior shell member and the outer surface of the interior shell member comprises a plurality of spaced-apart pins protruding from a respective one of the inner surface of the exterior shell member and the outer surface of the interior shell member.
In an embodiment, at least one of the exterior shell member and the interior shell member comprises helicoidal fiber windings adjacent to a respective one of the inner surface and the outer surface.
According to still another general aspect, there is provided a composite structural member assembly comprising: at least two composite structural members as described above; and at least one connector assembly connecting together the at least two composite structural members mutually perpendicularly and including at least one structural member abutting plate and a plurality of anchors, the at least one structural member abutting plate being superposable to an outer surface of at least one of the at least two composite structural members, each one of the anchors having an inner section extending in at least a respective one of the at least two composite structural members and an outer end section extending beyond the outer surface of the respective one of the at least two composite structural members and engaged with a respective one of the at least one structural member abutting plate, the at least one structural member abutting plate and the plurality of anchors being configured to secure together the at least two composite structural members in a mutually perpendicular configuration.
In an embodiment, a first one of the at least two composite structural members is a beam and a second one of the at least two composite structural members is a column and at least two of the anchors extend in an interior end spacing of the beam, the interior end spacing being defined between an end of the interior shell member spaced-apart inwardly along the longitudinal axis from a corresponding end of the exterior shell member. At least two of the anchors can extend in the column transversally to its longitudinal axis.
In an embodiment, at least two of the anchors are “L”-shaped anchors embedded in the concrete.
In an embodiment, the at least one structural member abutting plate comprises at least two structural member abutting plates, each one of the structural member abutting plates abutting an outer surface of a respective one of the composite structural members. At least two of the anchors can be straight anchors extending throughout the respective one of the composite structural members and having two opposed outer end sections, each one of the outer end sections being engaged with a respective one of the structural member abutting plates abutting opposite outer surfaces of the respective one of the composite structural members.
In an embodiment, the outer end section of the anchors is engaged with the respective one of the at least one structural member abutting plate through a retainer.
According to a further general aspect, there is provided a process for manufacturing a structural member. The process comprises: inserting an interior shell member having an inner channel in an elongated channel of an exterior shell member; inserting at least one reinforcement bar in an inter-shell spacing defined between the exterior shell member and the interior shell member; and filling the inter-shell spacing with concrete with the at least one reinforcement bar being embedded in the concrete.
In an embodiment, the process further comprises providing a concrete adherence improvement treatment to at least one of the inner surface of the exterior shell member, the outer surface of the interior shell member, and the inner surface of the interior shell member, the concrete adherence improvement treatment promoting cohesion between the treated surface and the concrete. Improving the concrete adherence further can comprise: applying a resin to the at least one of the inner surface of the exterior shell member, the outer surface of the interior shell member, and the inner surface of the interior shell member; and applying a granular material to the unset resin; adhering helicoïdal fiber windings to the at least one of the inner surface of the exterior shell member, the outer surface of the interior shell member, and the inner surface of the interior shell member; securing pins to the at least one of the inner surface of the exterior shell member, the outer surface of the interior shell member and the inner surface of the interior shell member; and machining grooves on the at least one of the inner surface of the exterior shell member, the outer surface of the interior shell member, and the inner surface of the interior shell member.
In an embodiment, inserting the at least one reinforcement bar in the inter-shell spacing comprises inserting plastic chairs in the inter-shell spacing to support the at least one reinforcement bar, spaced-apart from the inner surface of the exterior shell member and the outer surface of the interior shell member.
In an embodiment, the process further comprises inserting obstructing members in the inner channel of the interior shell member, the obstructing members being spaced apart from one another and each one being close to an opposed end of the interior shell member. Inserting the obstructing members in the inner channel of the interior shell member can comprise inserting the obstructing members in the inner channel, spaced-apart inwardly from the opposed ends of the interior shell member.
In an embodiment, the interior shell member has a length along the longitudinal axis shorter than a length of the exterior shell member along the longitudinal axis, and wherein inserting the interior shell member in the elongated channel of the exterior shell member with two opposed ends of the inner shell member being spaced-apart inwardly along the longitudinal axis from a corresponding end of the exterior shell member defining interior end spacings therebetween. Filling the inter-shell spacing with concrete can comprise covering the ends of the inner shell member with the concrete. The process can further comprise bending the at least one reinforcement bar to obtain a longitudinally extending section, extending along the longitudinal axis of the composite structural member, and a transversally extending section extending in one of the interior end spacings.
In an embodiment, filling the inter-shell spacing with the concrete can comprise filling opposed end sections of the inner channel with the concrete.
It will be noted that throughout the appended drawings, like features are identified by like reference numerals.
Referring now to the drawings and, more particularly, referring to
The outer surface 26 defines an outer peripheral shape of the composite structural member 20. The inner surface 28 defines an elongated channel 30 extending along the longitudinal axis 22. The composite structural member 20 further comprises an interior shell member 32 inserted in the exterior shell member 24 and, more particularly, in the elongated channel 30. In the embodiment shown, the interior shell member 32 extends along the entire elongated channel 30 of the exterior shell member 24. The interior shell member 32 has an outer surface 34 and an inner surface 36. The inner surface 36 defines an elongated inner channel 38. The outer surface 34 is spaced-apart from the inner surface 28 of the exterior shell member 24. In the embodiment shown, both the exterior shell member 24 and the interior shell member 32 have a circular cross-section and are concentric. Thus, the inner surface 28 of the exterior shell member 24 and the outer surface 34 of the interior shell member 32 are substantially evenly spaced-apart along an entire length of the interior shell member 32 and an elongated inter-shell spacing 35 is defined therebetween. In the embodiment shown, the elongated inter-shell spacing 35 has a substantially annular cross-section along the entire length of the composite structural member 20.
For instance and without being limitative, a ratio of the diameters of the interior shell member 32 and the exterior shell member 24 is between about 0.2 and about 0.8. For substantially rectangular shell members 24, 32, the diameter is intended to mean a length of a diagonal extending between opposed corners of the rectangular shell member 24, 32.
Each one of the exterior shell member 24 and the interior shell member 32 comprises two ends 40a, 40b and 42a, 42b, respectively. In the embodiment shown in
The composite structural member 20 further comprises reinforced concrete 44 in the elongated inter-shell spacing 35. More particularly, concrete 44 fills the elongated inter-shell spacing 35 between the inner surface 28 of the exterior shell member 24 and the outer surface 34 of the interior shell member 32. The concrete 44 comprises a plurality of reinforcement bars 46 extending mainly along the longitudinal axis of the composite structural member 20 to form reinforced concrete. The reinforcement bars 46 are not connected to either the exterior shell member 24 or the interior shell member 32, but can be connected to one another to define a reinforced concrete armature. The reinforcement bars, connected together or not, for the reinforced concrete armature.
In the embodiment shown, they are disconnected and spaced-apart from the exterior shell member 24 and the interior shell member 32, and are substantially uniformly spaced-apart from one another in the elongated inter-shell spacing 35 and surrounded by concrete. It will be appreciated that the number of reinforcement bars 46 and their disposition inside the inter-shell spacing 35 can vary from the embodiment shown. For instance and without being limitative, for beams, the reinforcement bars 46 can be provided mainly on a tension side of the beam. The reinforcement bars 46, disconnected and spaced-apart from the exterior shell member 24 and the interior shell member 32, increase the bending capacity of composite structural member 20.
To maintain the reinforcement bars 46 spaced-apart from the exterior shell member 24 and the interior shell member 32 and the interior shell member 32 spaced-apart from the exterior shell member 24 when concrete is poured in the inter-shell spacing 35, plastic chairs (or spacers) can be used to support the reinforcement bars 46 and the interior shell member 32 inside the exterior shell member 24.
To reduce the weight of the composite structural member 20, the elongated inner channel 38 defined by the inner surface 36 of the interior shell member 32 is hollow. However, in an alternative embodiment, it can be filled with a relatively light material, i.e. lighter than concrete, to reduce the weight of the composite structural member 20 while improving the mechanical performances.
If the elongated inner channel 38 of the composite structural member 20 is substantially hollow, the ends are obstructed when pouring concrete in the inter-shell spacing 35 to substantially prevent concrete infiltration therein. For instance, the ends can be obstructed with an obstructing member closing the ports of the inner channel 38. For instance and without being limitative, wood plates can be mounted to the ends 42a, 42b of the interior shell member 32 to prevent concrete infiltration in the elongated inner channel 38.
The exterior shell member 24 can be made of any of several suitable materials. For instance and without being limitative, it can include fiber reinforced polymer (FRP), steel, aluminum and aluminum alloys. It can also include two or more layers of similar or different material superposed on one another. In a particular embodiment, the exterior shell member 24 comprises fiber reinforced polymer (FRP).
The interior shell member 32 can be made of several suitable materials. For instance and without being limitative, it can include FRP, steel, aluminum, aluminum alloys, PVC and cardboard. It can also include two or more layers of similar or different material superposed on one another.
In an embodiment, the stiffnesses of the exterior shell member 24 and the interior shell member 32 are in a similar range.
If one or both of the exterior and interior shell members 24, 32 are made of FRP, they can be manufactured by filament winding, pultrusion, or any other suitable manufacturing processes. To modify the mechanical properties of the composite structural member 20, the number of layers and the orientation of the fibers can be adjusted.
The reinforcement bars 46 can be made of several suitable materials. For instance and without being limitative, they can be made of steel or composite materials such as fiber reinforced polymer bars. In the embodiment shown, the reinforcement bars 46 have a substantially circular cross-section. However, in an alternative embodiment, the cross-sectional shape of the reinforcement bars 46 can vary from the embodiment shown. For instance and without being limitative, the cross-sectional shape of the reinforcement bars 46 can be square, rectangular, triangular, trapezoidal, and the like.
Similarly, in the embodiment shown, the cross-sectional shape of the composite structural member 20, defined by the outer surface 26 of the exterior shell member 24, is substantially circular. However, in an alternative embodiment, the cross-sectional shape of the composite structural member 20 can vary from the embodiment shown. For instance and without being limitative, the cross-sectional shape of the composite structural member 20 can be substantially square, rectangular, triangular, and the like. The composite structural member 20 can have rounded corners to avoid damage due to stress concentration. For instance, the exterior shell member 24 can have a substantially rectangular cross-section with rounded corners.
In the embodiment, the exterior shell member 24 and the interior shell member 32 have substantially the same cross-sectional shape. However, in an alternative embodiment, the cross-sectional shape of the interior shell member 32 can differ from the cross-sectional shape of the exterior shell member 24.
In the embodiment shown, the exterior and interior shell members 24, 32 are concentric, i.e. their centers are aligned. However, in an alternative embodiment, the centers of exterior and interior shell members 24, 32 can be offset.
In the embodiment shown, the cross-section of the exterior and interior shell members 24, 32 is substantially uniform along their entire length, i.e. the exterior and interior shell members 24, 32 have a substantially uniform diameter/perimeter along their length. However, in an alternative embodiment (not shown), the cross-section of the exterior and/or interior shell members 24, 32 can vary along the length of the respective one of the exterior and/or interior shell members 24, 32. For instance, the exterior and/or interior shell members 24, 32 can be wider along a section thereof corresponding to a connection between two mutually perpendicular composite structural members, i.e. a beam and a column, providing increase retention of anchors in concrete, as will be described in more details below.
In an alternative embodiment, for beams, the interior shell member 32 can be shifted to the tension zone of the composite structural member 20. Thus, the interior shell member 32 acts as flexural reinforcement and supports the concrete 44, as will be described in more detail below in reference to
To promote concrete adhesion on the inner surface 28 of the exterior shell member 24 and the outer surface 34 of interior shell member 32, a concrete adherence improvement treatment can be applied before filling the inter-shell spacing 35 with concrete. The concrete adherence improvement treatment can include a concrete adherence improvement coating or other suitable concrete adherence enhancer to roughened the surface and thereby improve concrete adherence. For instance, at least one of the surfaces 28, 34 can be covered with a relatively thin polymeric layer, such as a resin. Then, a thin coating of sand or other suitable particles, which can be abrasive particles, can be applied on the polymeric coating while it is still sufficiently adhesive to bond the particles. The polymeric coating promotes adhesion of the particles on the surface of the shell members 24, 32. In one version of this embodiment, the particle size of the abrasive material is selected to promote concrete adhesion on the surface of the shell members 24, 32. For instance and without being limitative, the polymeric coating can include polymers used for PRF manufacturing, epoxy, polyester, vinylester, and the like.
Other adherence improvement treatments can be applied before filling the inter-shell spacing 35 with concrete. For instance, it can include adhering granular material to a resin on the surface of the tube(s), machining relatively narrow grooves on the surface of the tube(s), coiling helicoidal fibers around the tube(s), and mounting protruding members, such as pins, to the surface of the tube(s) by gluing, screwing, or any other suitable assembly method.
The concrete adherence improvement treatment or concrete adherence enhancer described above can also be applied to the inner surface 36 of the interior shell member 32. Optionally, the treatment can be applied only on one or more sections of the inner surface 36 of the interior shell member 32. For instance, the treatment can be applied to end sections of the inner surface 36 of the interior shell member 32 if concrete is filled at least partially therein, as will be described in more detail below.
As mentioned above, one embodiment of concrete adherence enhancer uses relatively narrow grooves machined on at least one of the inner surface 28 of the exterior shell member 24 and the outer surface 34 of interior shell member 32 to promote concrete adhesion. In a different embodiment, helicoidal fiber windings are adhered to at least one of the inner surface 28 of the exterior shell member 24 and the outer surface 34 of interior shell member 32 to promote concrete adhesion. It is appreciated that pins can also be mounted to at least one of the inner surface 28 of the exterior shell member 24 and the outer surface 34 of interior shell member 32 to promote concrete adhesion. For instance, plastic, aluminum, steel, or composite material pins can be adhesively mounted, such as glued, or mechanically mounted, such as screwed, to the surface of the shell members 24, 32.
Depending on the application, it is possible that only one of the inner surface 28 of the exterior shell member 24 and the outer surface 34 of interior shell member 32 includes a concrete adherence improvement treatment or concrete adherence enhancer. Alternatively, both the inner surface 28 of the exterior shell member 24 and the outer surface 34 of the interior shell member 32 can include such a treatment or enhancer. The concrete adherence improvement treatment applied to the inner surface 28 of the exterior shell member 24 and the outer surface 34 of interior shell member 32 can be the same or can be different.
In the composite structural member 20, the exterior shell member 24 provides a permanent formwork, a flexural reinforcement, and a replacement of shear reinforcement. Furthermore, in some implementations wherein the reinforcement bars 46 are embedded in concrete and surrounded by the exterior shell member 24, the exterior shell member 24 provides corrosion protection for the concrete 44 and the embedded reinforcement bars 46.
The reinforced concrete 44 acts as a compression member in addition to supporting the exterior and interior shell members 24, 32 against buckling, as will be described in more detail below. The reinforced concrete armature including the reinforcement bars 46 is used as tension device to strengthen and hold the concrete in tension. In some beam implementations, the reinforcement bars 46 reinforce the composite structural member 20 on the tension side.
As mentioned above, the composite structural member 20 has a lower weight than conventional structural members due to its hollow inner channel 38. For instance and without being limitative, between about 30% and about 80% of a volume of the composite structural member 20 is hollow.
Referring to
Furthermore, the exterior shell member 124 is longer than the interior shell member 132 along the longitudinal axis 122. Therefore, an interior end spacing 150 is defined between the ends 140a, 140b of the exterior shell member 124 and the ends 142a, 142b of the interior shell member 132, respectively. The ends 142a, 142b of the interior shell member 132 are located within the elongated channel 130. Like the inter-shell spacing 135, the interior end spacing 150 is filled with concrete. The inner channel 138 of the interior shell member 132 is substantially empty to keep down the weight of the composite structural member 120.
In an embodiment, a length of the interior shell member 132 is between about 30% to about 80% the length of the exterior shell member 124. In an embodiment and without being limitative, the length of the interior end spacing 150 is at least 10% of the length of the exterior shell member 124 to allow insertion of a connector assembly, as will be described in more detail below.
In the embodiment shown, at least some of the reinforcement bars 146 extend continuously from the inter-shell spacing 135 into the interior end spacing 150 to increase the bond between the reinforcement bars 146 and concrete. In some embodiments, at least some of the reinforcement bars extend continuously parallel to the longitudinal axis 122 in the inter-shell spacing 135 on a first side of the composite structural member 120, are bent and extend continuously in the interior end spacing 150, and can be bent and extend partially or continuously in the inter-shell spacing 135 on a second side of the composite structural member 120 to further increase the bond with concrete.
In the embodiment shown in
When end sections 145 of the inner channel 138 are filled with concrete but a middle section of the inner channel 138, extending between the end sections 145 is hollow, obstructing members, such as plates, are inserted in the inner channel 138, spaced-apart inwardly from ends 142a, 142b to substantially prevent concrete infiltration into the middle section but to fill the end sections 145 with concrete. For instance and without being limitative, wood plates can be inserted in the inner channel 138 of the interior shell member 132 to prevent concrete infiltration in the middle section of the inner channel 38.
The concrete thickness on a first side 152 of the composite structural member 120, i.e. the tension side of the beam, is thinner than on a second side 154, opposed to the first side 152, i.e. the compression side of the beam.
The composite structural member 120 shown in
As for the above-described embodiment, the number, the disposition, and the configuration of the reinforcement bars 146 forming the reinforced concrete armature can vary from the embodiment shown.
In addition, the inner surface 128 of the exterior shell member 124 and the outer surface 134 of interior shell member 132 can include a concrete adherence improvement treatment to promote cohesion with concrete.
As shown in
Referring to
Furthermore, the exterior shell member 224 is longer than the interior shell member 232 along the longitudinal axis 222 and extends past the interior shell member 232 at ends 240a, 240b, 242a, 242b. Therefore, the composite structural member 220 comprises two interior end spacings 250 which are filled with concrete. Once again, the inner channel 238 of the interior shell member 232 is empty to keep down the weight of the composite structural member 220. In the embodiment shown, the composite structural member 220 is represented with only one reinforcement bar 246. However, it is appreciated that the reinforced concrete armature of the composite structural member 220 can include several reinforcement bars, which can be connected to one another, and the number, the disposition, and the configuration of the reinforcement bars can vary. The reinforcement bar 246 extends continuously from the inter-shell spacing 235 into one of the interior end spacings 250. More particularly, the reinforcement bar 246 has a first longitudinally extending section 246a extending continuously substantially parallel to the longitudinal axis 222 in the inter-shell spacing 235 on the first side 252 of the composite structural member 220, is bent to form a second transversally extending section 246b extending continuously in the interior end spacing 250 in a lateral direction, and is further bent to form a third section 246c extending partially in the inter-shell spacing 235 on the second side 254 of the composite structural member 220. The three sections 246a, 246b, 246c form a hook which substantially prevents displacement of the reinforced concrete armature inside concrete. The interior shell member 232 and the reinforcement bar 246 are entirely surrounded by concrete and are not visible from the outside.
In one version of the
As with the above-described embodiments, the inner surface 228 of the exterior shell member 224 and the outer surface 234 of interior shell member 232 can include a concrete adherence improvement treatment or a concrete adherence enhancer to promote cohesion with concrete.
The reinforced concrete armature can optionally comprise one or more transversally extending reinforcement members (not shown) defining a loop surrounding the interior shell member 32, 132, 232 and extending between the inner surface 28, 128, 228 of the exterior shell member 24, 124, 224 and the outer surface 34, 134, 234 of the interior shell member 32, 132, 232. As the longitudinally extending reinforced members, the transversally extending reinforcement members are spaced-apart of and disconnected from the exterior shell member 24, 124, 224 and the interior shell member 32, 132, 232. While the exterior shell member 24, 124, 224 can provide the required shear strength, if needed, the use of such transversal reinforcement member(s), which can also be referred to as stirrups, inside concrete 44, 144, 244, can increase the shear resistance. In an embodiment, the composite structural member is free of transversally extending reinforcement member.
As for the embodiment described in reference to
Referring now to
To simplify the figures in the below described implementations of connector assemblies, the inner structure of the structural composite members is not entirely shown. Solely, the elongated inner channel is schematically represented. However, it is appreciated that the structural composite members have an internal structure including a reinforced concrete armature as described above in reference to
More particularly, the structural composite members 320a, 320b are connected through a connector 360. The connector 360 is substantially an I-beam 362 with two structural member abutting plates 364. Each of the structural composite members 320a, 320b is manufactured with four anchors 366 having a first section extending therein and a second section extending outwardly. In the implementation shown, the anchors 366 are substantially “L”-shaped anchors. It is appreciated that the shape, the number and the configuration of the anchors 366 can vary from the implementation shown. Four apertures are defined in each of the structural member abutting plates 364 of the connector 360 and the second section, i.e. the end section, of the anchors 366 extending outwardly are inserted in a respective one of the four apertures. The outer surfaces 326 of the structural composite members 320a, 320b are juxtaposed to a respective one of the structural member abutting plates 364 of the connector 360 and the anchors 366 are secured in this engaged configuration. For instance, at least part of the end section of the anchors 366 can be threaded and retaining elements, such as nuts, can be attached to secure the anchors 366 to the connector 360 and, more particularly, the structural member abutting plates 364.
In an embodiment, the “L”-shaped anchors 366 are inserted in the inter-shell spacing before pouring concrete therein. When concrete is poured in the inter-shell spacing, the anchors 366 are secured therewith.
As shown in
In an embodiment, the anchors 366 can be provided in pairs with their inner end sections extending in opposite directions as shown in
When engaged with the interior and exterior shell members, an end section of the anchors 366 extend outwardly of the outer surface 326 of the structural composite members 320a, 320b. As shown in the figures, the end section of the anchors extending outwardly of the structural composite members 320a, 320b can be threaded. In an embodiment, the anchors 366 are positioned to not interfere with the reinforcement bars 46, 146, 246 extending in the inter-shell spacing 35, 135, 235.
Referring now to
Each one of the structural member abutting plates 470 comprises eight apertures, four of the apertures being associated with each one of the structural composite members 420a, 420b, respectively. The anchors 466 are inserted through each of the structural composite members 420a, 420b with end sections thereof extending outwardly on each side of the structural composite members 420a, 420b. The structural member abutting plates 470 are engaged with the anchors 466 by inserting the end sections into respective ones of the apertures. Each one of the apertures of a first one of the structural member abutting plates 470 is aligned with a respective one of the apertures of a second one of the plates 470. The structural member abutting plates 470 are juxtaposed to the outer surfaces 426 of the structural composite members 420a, 420b, each one of the plates 470 extending on a respective side of the structural composite members 420a, 420b. The anchors 466 and the structural member abutting plates 470 are secured together in this engaged configuration. For instance, at least part of the end sections of the anchors 466 can be threaded and retaining elements, such as nuts, can be attached thereto to secure the anchors 466 to the structural member abutting plates 470.
The anchors 466 can be engaged with the exterior shell member before pouring concrete in the inter-shell spacing. When concrete is poured in the inter-shell spacing, the anchors 466 are embedded therewith. Alternatively, molding elements can be inserted between the exterior and interior shell members before pouring concrete therein to define hollow channels in the composite structural members 420a, 420b. Straight anchors 466 can be subsequently inserted in the hollow channels to connect two composite structural members 420a, 420b together.
Straight anchors 466 extend substantially normal to the longitudinal axis of the structural composite members 420a, 420b. For beam 420a, the anchors 466 extend in the interior end spacings filled with concrete, i.e. between an exterior shell member and the adjacent end of the interior shell member. Sections of the reinforced concrete armature can also extend in the interior end spacings, as described above. For column 420b, a section of the anchors 466 extend partially through the elongated inner channel 438, perpendicularly thereto.
Referring now to
The “L”-shaped anchors 566 are inserted in the interior end spacings of beam 520a before pouring concrete in the inter-shell spacing. Therefore, the “L”-shaped anchors 566 are embedded in concrete filling the interior end spacings of beam 520a.
As shown in
Referring now to
Each of the structural composite members 620b, 620c is connected to the structural composite member 620a through a connector assembly 660. Each connector assembly 660 comprises two corner braces 672, two structural member abutting plates 670, and four straight anchors 666. The corner braces 672 are mounted on two opposed sides of each respective structural composite member 620b, 620c. Each one of the corner braces 672 is substantially “L”-shaped and has a first structural member abutting plate 674a and a second structural member abutting plate 674b, extending substantially perpendicularly to the first plate 674a, and a reinforcing web 676 extending between and connecting the first and second structural member abutting plates 674a, 674b. The shape of the corner braces 672 can vary from the implementation shown. The first structural member abutting plate 674a abuts a corresponding one of the structural composite members 620b, 620c and a second structural member abutting plate 674b abuts the structural composite member 620a. The structural member abutting plates 670 are abutted against the structural composite member 620a, on the face opposed to the face abutted by the corresponding one of the corner brace 672, and aligned with the corner brace 672. Straight anchors 666 extend in the structural composite member 620a and in apertures defined in the corner brace 672 and the aligned one of the structural member abutting plates 670. Two anchors 666 are associated with each one of the second plates 674b of the corner braces 672 and the corresponding one of the structural member abutting plates 670, each of the anchors 666 being mounted on a respective side of the web 676. The additional anchors 666 of each connector assembly 660 extend through the respective one of the structural composite members 620b, 620c, passing through apertures defined in the first structural member abutting plates 674a of the opposing corner braces. End portions of the anchors 666 extend outwardly past the corner braces 672 and structural member abutting plates 670, and are secured thereto by a retaining element. In the implementation shown, the end portions of the anchors are threaded and retaining elements, such as nuts, are used to secure the anchors 666 to the structural member abutting plates 674 and the structural member abutting plates of the corner braces 672.
The anchors 666 can be engaged with the exterior shell members before pouring concrete in the inter-shell spacing. When concrete is poured in the inter-shell spacing, the anchors 666 are embedded therewith. Alternatively, molding elements can be inserted between the exterior and interior shell members before pouring concrete therein to define hollow channels in the composite structural members 620a, 620b. Straight anchors 666 can be subsequently inserted in the hollow channels to connect two composite structural members 620a, 620b together.
Straight anchors 666 extend substantially normal to the longitudinal axis of the structural composite members 620a, 620b, 620c. For beams 620b, 620c, the anchors 666 extend in the interior end spacings filled with concrete, i.e. between an exterior shell member and the adjacent end of the interior shell member. Sections of the reinforced concrete armature can also extend in the interior end spacings, as described above. For column 620b, a section of the anchors 666 extend partially through the elongated inner channel 638, perpendicularly thereto.
Referring now to
For the implementations of
Straight anchors 666, 766 extend substantially normal to the longitudinal axis of the structural composite members 620a, 620b, 620c, 720a, 720b, 720c. For beams 620b, 620c, 720b, 720c, the anchors 666, 766 extend in the interior end spacings filled with concrete, i.e. between an exterior shell member and the adjacent end of the interior shell member. Sections of the reinforced concrete armature can also extend in the interior end spacings, as described above. For column 620a, 720a, a section of the anchors 666, 766 extend partially through the elongated inner channel 638, 738, perpendicularly thereto.
Referring now to
The connector assemblies 860 are similar to the connector assemblies 760 described above, except that each connector assembly includes two sets of anchors 866a, 866b. However, instead of using anchors that all pass completely through one of the structural composite members, some of the anchors 866a of the present implementation are substantially “L”-shaped anchors that have a section that is embedded in the interior end spacings of the beams 820b, 820c, filled with concrete. An end section of the anchors 866a extends beyond the surface of the structural composite member, and passes through an aperture of one of the structural member abutting plates 874 of the corner braces 872. The “L”-shaped anchors 866a of each beam 820b and 820c have threading on the exterior portion, by which retaining elements, such as nuts, may be used to secure them to their respective corner braces 872. The other structural member abutting plates 874 of the corner braces 872 are secured to the column 820a by straight anchors 866b that pass completely through the column 820a and are secured to respective structural member abutting plates 870 on the opposite side. In the implementation shown, the two ends of these anchors 866b are threaded and retaining elements, such as nuts, are used to secure them at both sides.
As for the above described implementations, the “L”-shaped anchors 866a are inserted in the interior end spacings before pouring concrete therein. Straight anchors 866b can be either engaged with the shell(s) before pouring concrete therebetween or inserted in hollow channels defined in concrete.
Referring now to
The connector assemblies 960 are similar to the connector assemblies 860 described above. However, the anchors 966 inserted in all three structural composite members 920a, 920b, 920c are “L”-shaped anchors, like those shown in
Referring now to
The structural composite members 1020b, 1020c, 1020d, i.e. the beams, extend at the same longitudinal position along the structural composite member 1020a, i.e. the column, and perpendicularly thereto.
The connector assemblies 1060 are similar to the connector assemblies 660 described above in reference to
Referring now to
The connector assemblies 1160 are similar to the connector assemblies 760, 1060 described above in reference to
Referring now to
The connector assembly 1260 is similar to the connector assembly 1160 described above in reference to
Referring now to
The implementation of
Referring now to
In this implementation, the ends of the structural composite members 1420a, 1420b are mounted in an adjacent configuration through the connector assembly 1460. The connector assembly 1460 includes a corner brace 1472 with two structural member abutting plates 1474 and eight “L”-shaped anchors 1466. Each one of the structural member abutting plates 1474 abuts a respective end of the structural composite members 1420a, 1420b. The corner brace 1472 also includes two reinforcing webs 1476 extending between the structural member abutting plates 1474 and being spaced-apart from one another. The “L”-shaped anchors 1466 extend in the interior end spacings of a respective one of the structural composite member 1420a, 1420b and in apertures defined in the structural member abutting plates 1474 of the corner brace 1472, between the two reinforcing webs 1476. The anchors 1466 are inserted in the interior end spacings before pouring concrete therein.
Referring now to
Each one of the beams 1520b, 1520c, 1520d comprise two “L”-shaped anchors 1566 embedded in concrete of the interior end spacing, normal to the longitudinal axis. An end section of each one of the “L”-shaped anchors 1566 extend outwardly of the respective beam 1520b, 1520c, 1520d and through an aperture defined in a structural member abutting plate 1570. The structural member abutting plate 1570 abuts an outer face of the exterior shell member, close to an end of the beam 1520b, 1520c, 1520d, and is secured with retaining elements mounted to the end sections of the anchors 1566.
The connector assemblies 1560 of beams 1520b, 1520d further includes a corner brace 1572, each one including two plates 1574 at end thereof and through two spaced-apart reinforcing webs 1576. One of the two plates 1574 abuts the outer surface of the exterior shell member of column 1520a while the other one extends under a respective one of the beams 1520b, 1520d and is spaced-apart therefrom. The plates 1574 abutting the outer surface of the exterior shell member of column 1520a are connected together through straight anchors 1566 extending through the column 1520a.
The connector assembly 1560 of beam 1520c includes a plate 1570 extending perpendicularly to the outer surface of the exterior shell member of column 1520a and connected to the other connector assemblies 1560 through two spaced-apart reinforcing webs 1576. Plate 1570 extends below beam 1520c.
Plate 1570 and each one of the plates 1574 is connected to a respective one the beams 1570b, 1570c, 1570d through a pivoting assembly 1580. Each one of the pivoting assembly 1580 has a section mounted to the structural member abutting plate 1570 abutting the respective one of the beams 1570b, 1570c, 1570d and another section mounted to one of plate 1570 and a respective one of the plates 1574. The two sections are connected together through a hinge pin.
It is appreciated that similar connector assemblies can be used to connect one or more beams to a column.
Referring now to
The implementation of
As for the implementations described above, it is appreciated that similar connector assemblies can be used to connect one or more beams to a column.
For all implementations described above and combination thereof, for anchors being “L”-shaped anchors, the anchors are engaged with the outer shell member of the corresponding structural composite member before pouring concrete the inter-shell spacing. Thus, the “L”-shaped anchors are at least partially embedded in concrete.
The columns of the above described embodiments can include a wider section along their length aligned with the perpendicularly extending beam(s). The anchors of the connectors can extend through the wider section, thereby enhancing the bond between the anchors and the column concrete.
It will be appreciated by those skilled in the art that a connexion described in reference to two adjoining structural composite members can be used to connect three or more structural composite members. It will also be appreciated that a connexion described in reference to three or four adjoining structural composite members can be used to connect more or fewer structural composite members together. Combinations of the above-described connexions can be used to connect two or more composite structural members together.
An embodiment of a process to manufacture the composite structural member will now be described.
The desired mechanical properties of the composite structural member, either a beam or a column, are first determined. Then, the materials are selected for the interior and exterior shell members as well as the concrete and the reinforcement bar(s). The composite structural member can be designed by simulation, for instance with a Finite Element Method (FEM). It is thus possible to determine the size of the cross-section, the thickness of the interior and exterior shell members, the number and the configuration of the reinforcement bar(s), the length of the interior shell member, and the like. If the interior shell member or the exterior shell member is made of fiber reinforced polymer (FRP), the number of composite layers and the orientation of the fibers can be determined.
Once the composite structural member is designed, the interior and exterior shell members and the reinforcement bar(s) are manufactured. If the interior shell member or the exterior shell member is made of FRP, different manufacturing processes can be used, such as filament winding, pultrusion and injection. Different fibers/resins combinations can be used to build FRP shell members including, but not limited to, glass fibers, aramid fibers, carbon fibers, basalt fibers, and vinyl ester resins, epoxy resins, polyester resins. Additives can be used in the resin mixture to protect the exterior shell member from UV degradation.
Concrete adherence improvement treatments, as described above, can be applied to one of the outer surface of the interior shell member and the inner surface of the exterior shell member.
The interior shell member is inserted in the exterior shell member and positioned longitudinally and radially therein. The reinforcement bar(s) is (are) then inserted in the inter-shell spacing and positioned longitudinally and radially therein. Plastic chairs (or spacers) are used to support the reinforced concrete armature in the inter-shell spacing. If required by the design of the composite structural member, sections of the reinforcement bar(s) can be bent. The ends of the interior shell member are then closed at an inside given length to ensure that the inner channel remains substantially empty for a specified length when concrete is poured in the inter-shell spacing. Also, when required, any anchors that are part of a connector assembly are inserted and positioned. Finally, concrete is poured in the inter-shell spacing in a conventional manner. This can be followed by additional steps, such as waiting for the curing of the concrete, testing the quality control of the composite structural member, and the like.
Three types of beams were tested under pure bending: a conventional reinforced concrete (RC) beam, a fully concrete-filled fiber reinforced polymer (FRP) shell member (CFFT) beam, and a partially CFFT beam. The test included two identical partially CFFT beams. These beams have been tested up to failure. All the beams had the same cross sectional area and span, and were cast using the same concrete batch. Fabrication of the shell members, materials used, beam specimens details, and test setup and installments are detailed below.
Two different sizes of FRP shell members were fabricated for the example. The exterior shell member had a rectangular cross section of 305×406 mm with rounded corners having a 25 mm radius to avoid damage due to stress concentration. The interior shell member had a circular cross section with a 218 mm diameter. E-glass fibers and vinyl ester resin were used to fabricate the shell members. The shell members were fabricated by a filament-winding process in the civil engineering department at Sherbrooke University in Sherbrooke, Quebec. Only two winding patterns were used; a helical pattern with an orientation angle of 30° and a circumferential pattern with an angle of 90°. The helical pattern (30°) was used mainly to present the longitudinal reinforcement and was used to designate the exterior shell members, while the circumferential pattern (90°) was used to provide shear reinforcement and to prevent buckling of the longitudinal fibers. The identification of the interior shell members depends only on the helical pattern angle and the number of layers. All exterior shell members with a rectangular cross section had a laminate structure of [90°, ±30°, ±30°, 90°, ±30°, ±30°, 90° ] (=8 layers 30°+3 layers 90°), the identification is O830. All interior shell members had a circular cross section laminate structure of [90°, ±30°, ±30°, 90° ] (=4 layers 30°+2 layers 90°), the identification is I430.
After completion of the filament winding process, the exterior and interior shell members were heated for 24 hours at 60° C. to be cured. After pulling the mandrel out of the cured shell members and cleaning them, the surfaces intended to be adjacent to concrete were sand coated by a layer of epoxy resin and coarse sand to produce a rough texture in order to enhance the bond between concrete and the exterior and interior shell members. Then, the exterior and interior shell members were cut to the required length of beam specimens.
For all exterior and interior shell members, the tensile strength in the longitudinal and lateral direction was measured. For the rectangular exterior shell members, six identical coupons in the longitudinal direction and another six coupons were tested under tension following ASTM D 3039/D 3039M (ASTM D 3039/D 3039M, Standard test method for tensile properties of polymer matrix composite materials, American Society for Testing of Materials, West Conshohocken, Pa., USA, (2000)). The test was carried out on the interior shell members in the longitudinal direction, while the split disk test was used to measure the tensile strength in the hoop direction according to ASTM D 2290 (ASTM D 2290, Apparent Hoop Tensile Strength of Plastic or Reinforced Plastic Pipe by Split Disk Method, American Society for Testing of Materials, West Conshohocken, Pa., USA (2008)). For each coupon, the average width and thickness of the central part was measured to get the effective sectional area to calculate the effective stress. The tests were performed using MTS press 810. An extensometer was placed on the specimen in order to measure strain. A data acquisition system connected to the machine recorded the loads, axial displacement, and axial strain. Table 1 lists the configurations and mechanical properties of the shell members.
Two different steel bar sizes were used to reinforce beam specimens; deformed steel bars 10M and 15M, i.e. diameters of 10 mm and 15 mm respectively. The mechanical properties of the steel bars were obtained from standard tests that were carried out according to ASTM A615/A615M (ASTM A615/A615M, Standard specification for deformed and plain carbon steel bars for concrete reinforcement, West Conshohocken, Pa., USA, (2009)), on five specimens for each type of the steel bars. The mechanical properties of the steel bars are listed in Table 2.
A total of four beam specimens, each 3.2 m in length, were used: one conventional steel-RC beam, one fully CFFT beam, and two identical partially CFFT beams were tested under flexure. The conventional RC beam was reinforced with 4φ15 bottom reinforcement, 2φ10 as a top reinforcement, and stirrups φ10@150 mm as shear reinforcement. The rectangular CFFT beam was completely filled with concrete and reinforced only with 4φ15 bottom reinforcement (O830-S, wherein the “S” stands for the steel bars used as reinforcement bars). The two partially CFFT beams (O830-I430-S) used exterior and interior FRP tubings. They had the same exterior FRP shell member, as O830-S, and were reinforced with the same bottom reinforcement 4φ15. The hole was provided by an interior circular FRP shell member shifted towards the tension zone, 45 mm below a central longitudinal axis of the exterior shell member. The length of the interior circular FRP shell members was 2.4m, shorter than the length of exterior FRP shell members to keep the solid part at the support to prevent any local failure or web buckling at this region during the test.
The RC beams were cast horizontally in a wooden box formwork. Strong steel inclined formwork with an inclination angle of 25° was used to cast the concrete into shell members. The inclined formwork was used to simplify pouring concrete from the end gate and filling the shell members. Supporting the shell members against movement and blocking the end of the shell members was enough to begin the casting process. The shell members worked as permanent formwork. All beam specimens were cast with the same concrete batch. The concrete was a ready supplied patch. Its workability was enhanced by a super plasticizer additive. The average standard concrete compressive strength at 28 days was 36.7 MPa.
The beam specimens were tested using four-points bending as shown in
The behavior of fully or partially CFFT with the conventional RC beam as a reference was compared in terms of strength and failure mode. Table 4 shows the summary of test results.
The conventional RC beam failed in tension under flexure. Vertical flexural cracks at the pure moment zone, and no diagonal cracks at shear zone were noted as shown in
Fully CFFT beam (O830-S)
The fully CFFT beam (O830-S) was stiffer and stronger than the RC beam. The overall behavior is considered nonlinear, because of the nonlinearity of the concrete and the FRP shell members. The nonlinearity behavior in FRP shell members was obtained by the stacking sequence of the fibers in the composite. O830-S beam behavior started semi linear until reaching the yielding of the embedded reinforcement steel at point B. Then the slope was changed until reaching point E, where outward local buckling at the top flange and separation from the concrete occurred. This was the first warning sign of the failure. After point E, the shell member continued to carry an additional load depending on its whole section, especially the bottom flange, until it reached maximum failure load at point D. At this point, aggressive tension failure of the FRP shell member occurred suddenly by rupture of fibers at the tension side, as shown in
First cracks and yielding of steel were delayed compared with the RC beam. The increase of first crack load and yielding load was 100% and 78%, respectively compared with the RC beam. This was due to the confining action and the rough inner surface of the shell member which hampered crack propagations, in addition to the reinforcement ratio which was increased by the thickness of the shell member. Finally, the maximum capacity of O830-S beam was 300% more than the capacity of the conventional RC beam at failure. All previous notations mean very good performance for this type of rectangular CFFT.
Enhancement in the behavior of the partially CFFT beam (O830-I430-S) was also obtained in comparison with the conventional RC beam. O830-I430-S failed first at the top flange by rupture of the FRP shell member in a lateral direction of the shell member followed by buckling collapse of the interior shell member, which was noted by outward buckling of the exterior shell member sides, as shown in
The first cracking load and yielding load were increased by 40% and 97%, respectively compared with RC beam. The cracking load of the voided beam was 36% smaller than that of the fully CFFT beam (O830-I430-S) because of subtracting the hole area from gross section. On other hand, the yielding load was 10% more than the fully CFFT beam because of adding the area of interior shell member thickness to the reinforcement area at the tension zone in the cracked section. Both CFFT beams (fully and voided) could be considered to have identical flexural stiffness. Finally, the partially CFFT (O830-I430-S) capacity was 240% more than the capacity of the conventional RC beam and had better performance.
Although the flexural strength of the partially CFFT was 24% lower than that of the fully CFFT, the dead weight of it was 30% lighter than the fully one, resulting in an overall strength-to-weight ratio for O830-I430-S, 10% higher than O830-S. Since the failure began with rupture of fibers in a lateral direction and buckling collapse of the interior shell member, increasing the fiber percentage in the lateral direction of both the exterior and interior shell members and increasing the thickness of the interior shell member could enhance the strength of the partially CFFT. Also, providing an interior shell member having a substantially rectangular shape could prevent the buckling of the interior shell member and enhance the beam behavior.
The above-described composite structural member is relatively simple in construction and the shell members provide permanent formwork in addition to acting as reinforcement in the axial and lateral directions. In some implementations, the above-described composite structural member showed higher ductility, higher stiffness, and superior strength than the conventional RC beams. Furthermore, the rectangular fully CFFT beam failed aggressively in the tension side by rupture of fibers after buckling of the FRP compressive flange. The partially CFFT beam failed by rupture of FRP shell member in a lateral direction of the shell member at compressive flange followed by collapse of the interior shell member. The failure pattern of the partially CFFT beam was not aggressive like the failure pattern of the fully CFFT beam, but some residual strength remained after failure.
Moreover, although the embodiments of the composite structural member and corresponding parts thereof consist of certain geometrical configurations as explained and illustrated herein, not all of these components and geometries are essential and thus should not be taken in their restrictive sense. It is to be understood, as also apparent to a person skilled in the art, that other suitable components and cooperation therebetween, as well as other suitable geometrical configurations, may be used for the composite structural member, as will be briefly explained herein and as can be easily inferred herefrom by a person skilled in the art. Moreover, it will be appreciated that positional descriptions such as “above”, “below”, “left”, “right” and the like should, unless otherwise indicated, be taken in the context of the figures and should not be considered limiting.
It will be appreciated that the methods described herein may be performed in the described order, or in any suitable order. Several alternative embodiments and examples have been described and illustrated herein. The embodiments of the invention described above are intended to be exemplary only. A person of ordinary skill in the art would appreciate the features of the individual embodiments, and the possible combinations and variations of the components. A person of ordinary skill in the art would further appreciate that any of the embodiments could be provided in any combination with the other embodiments disclosed herein. It is understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein. Accordingly, while the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.
This application claims priority under 35USC§119(e) of U.S. provisional patent application No. 61/897,429 filed on Oct. 30, 2013, the specification of which is hereby incorporated by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CA2014/051045 | 10/30/2014 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61897429 | Oct 2013 | US |
