Patent Application
20220396963
The invention is an application in the field of construction engineering and specifically relates to a massive wood hybrid cutting wall structural system for the construction of buildings of 5 or more floors applicable in seismic zones, which provides protection against extreme load events, such as ties or strong winds.
The earthquake's are unpredictable and sudden natural events, which cause large human losses normally caused by the damage caused in the infrastructure of a population. In some cases, the very strong winds, including the cyclones, can also cause movements in buildings and structural damage.
In the latter decades, the work has been increased in the design and development of construction systems for concrete and steel buildings of various floors for regions subject to seismic activity, looking primarily to prevent catastrophic failure of the building and protect life.
The different problems derived from the occurrence of an earthquake, in terms of infrastructure damage, have led to construction technologies that allow the construction of buildings capable of withstanding earthquake without structural damage, in order to reduce the economic cost of building repair and/or reconstruction, as well as minimizing the time of inactivity in the use of the in furniture during such repair or repair periods after an earthquake or any other destructive event.
There are several factors which, in recent years, have led to searching for different construction solutions to the use of steel and concrete, which not only meet the structural requirements of the materials, but also have an important reduction in the time of construction, the costs and the environmental effects that are derived from the different building techniques.
In that sense, such factors have been relevant in the increase in the use of frame wood panels (lightweight wood framing) and the use of massive or solid wood panels, such as cross laminated wood (CLT) panels, vertically laminated veneer panels (LVL) and parallel strand Wood panels (PSL) in construction and construction projects of more than two or three floors. One of the main advantages of construction with this type of wood panels is the low weight that they have and therefore exhibit reduced design forces; on the other hand, construction with this type of panels allows for an accelerated line of building time as compared to conventionally used construction materials and processes, and can be reduced from months to just weeks. This is greatly enhanced because construction with this type of wooden panels allows for a line of prefabricated materials that can be conceived in specialized spaces for this and then transported to the area of the construction where they are mounted.
An additional factor that is driving the increase in the demand for wooden panels in construction projects is the difference in the field labor types required; the construction of a structure with wooden panels of this type requires general specialization workers or workers, while traditional multi story construction projects that, use concrete and steel require specialized labor in concrete finishes and swingers, generally at higher operating rates than the characters and workers of general specialization.
Another factor that has driven not only the demand for panels made entirely of wood for buildings, but also the demand for mixed panels, with frames of prefabricated concrete or steel materials and normally with wood veneer sheathing, is the environmental benefit from the cleaning in the construction, the waste and the recycling capability of the materials, which in the case of construction with prefabricated wooden panels or steel frames it is more clean and completely recyclable; in both the traditional construction with reinforced concrete in situ in situ, it involves a process that is quite dirty, leaves many waste, and in terms of recycling capability, it presents a large problem, since if the seam is recyclable, concrete is not, requiring an expensive and complex destruction process to achieve the separation of two different materials and to recover the flashing in the event that the demolition of the building is carried out.
This type of composite panel based construction can be seen as described in U.S. Pat. No. 3,975,510 (B2) of Miller, C, which discloses a structural panel system for use in lightweight construction, typically of a floor or two; in that case, although the disclosed panels are mixed by the use of an inner frame which may be wood or metal coated by wooden plates on each side and joined by screw type connectors this type of systems does not allow construction of more than two floors used as cutting walls, as by the thicknesses of the materials, the framing of the frame and mainly by the connecting means, it is seen that they are for low load stress structures with low, seismic resistance.
In particular, this type of systems use very thin wood plates, 11 to 15 mm. If they are of OSB or plywood, where that thickness is not sufficient to embed connectors of diameters that generate a sufficiently ductile and strong connection capable of dissipating energy. Thus, the main disadvantage of this type of light systems is that they do not possess structural capability for building seismic loads of 5 to 10 floors.
In the foregoing, other construction systems have been developed for testing seismic events, where the use of thicker wooden panels offering much greater strength capabilities has been sought, which are not equivalent to the use of boards Like the OSB or plywood, but have thicknesses greater than 60 millimeters, such as cross laminated wood (CLT cross laminated tiber).
This is seen in Japanese patent application JP2018080569 (A) published 24 May 2018 Of Saadahiiro Osu, the al which proposes a large wall of wood, which is aimed at preventing brittleness, through a wall comprised of vertically stacked CLT panels, but separated by a dilation, each of the high half of the interfloor, there is a top attached to an upper beam of a steel frame by a high strength connection, and there is another lower panel joined to a lower beam of the frame, respectively by the same connection; in this case, the energy dissipation comes from a plate, like connector element coplanar between the two wall panels, which is designed with a lower resistance than the joints between the CLT panels and the steel beams. The disadvantage or problem with this solution is that all the working of the CLT is concentrated in a single location, i.e, the entire transmission of the cut and the dissipation is concentrated in the coplanar connector element disposed between the two panels so as to work a small portion of the CLT panels, making it unreliable; it is also seen that there are different types of connections, one between the panels of the CLT to the frame and the other between said panels the energy dissipation scheme in this patent is the plate type connector of the medium which concentrates all of the deformation and cutting, since the upper junctions are many with glued steel bars, they do not dissipate energy.
In various solutions of this type, the problem arises that the steel frame used and the CLT are two resistant systems that work in parallel and do not form a single system; the steel frame primarily resists vertical forces while the CLT wall resists lateral forces, so that in this type of structures the gravitational system is separated from The CLT, specifically in this newly cited document are large beams which carry the loads to the columns, this is evidenced by noting that the CLT has a dilation and is separated, therefore it does not transmit vertical load.
On the other hand, this type of system does not address the lifting problem, so that they do not offer solutions that avoid the effect of rollover or rocking and in the case of this Japanese patent the main steel structure is used, that frame is which transfers the moment and rollover, Does Not do the CLT, which requires dimensionally important beams, making them in a low cost and cost efficient system. When a steel frame is the main structure, and operating the CLT alone as a bracing device at lateral forces to give rigidity to the main frame, it is a much more flexible system and therefore, with a lack of sufficient rigidity so as to resist large seismic forces and to meet the structure with a displacement or drift (which is the maximum horizontal deformation allowed between two floors in a seismic event) as set forth in construction standards in most territories of high seismic concurrence.
In the prior art, some solutions are known that point to solving the problem of the dumping effect and hence the problem of the interstory displacement that is produced by cars, such as the use of tendons which are seen in German Patent application AU201577979 (al) published 15 Jun. 2015 of Murray Parkson, L, where a Connecting system for walls stacked in height of a building is described, which enables post tensioning said walls. This system uses the CLT and a series of arrays by means of steel tubes and cables which have the characteristic of providing resistance to lateral forces (wind and sism). This document contains arrangements that help solve the problem of tilting or dumping the CLT panels, but does not quantify how much helps to improve the ductility.
On the other hand, the most important disadvantage is that it is a fairly elaborate system, then requires the manufacture of many special parts that are possibly quite expensive when they wish to be used in a building that is located in a high temperature area. It requires many pieces and steel components to be manufactured with very good precision, i.e, it requires specialized manufacturing, to ultimately assemble all this in the wall requiring many in situ labels that do not lack the construction. Placing all of the above in walls of buildings in a high seismic area, where most of them are arranged as cutting structural walls, and each of them requires all of these tubes and steel pieces to be very costly. Therefore, it is believed that this may be of utility in zones of low stress, where only a few walls are required to be cut structural.
The construction based on massive wooden panels, such as cross laminated wood panels (CLT), have as a main feature that are self-supporting and allow for the rapid prefabrication of dwellings and buildings, being used in slabs, ceilings and as cutting walls in order to obtain more rigid structures.
In structural engineering, a cutting wall is a structural system comprised of rigid wall panels to counteract the effects of lateral loading in the plane acting on a structure. The wind and the seismic loads are the most common loads that the cutting walls are designed to resist.
By virtue of various construction standards, the designer is responsible for designing an appropriate amount, length and arrangement of the cutting wall lines in both orthogonal directions of the building to securely resist imposed lateral loads. The cutting walls can be located along the outside of the building, inside the interior of the building or in a combination of both.
When a cutting wall is subjected to a rollover or rocking force, the connectors and anchors distort and this rollover force imposes a horizontal displacement in the lateral system or vehicle. The strength of the wood cutting walls is an important factor in determining the response of the cutting walls to the wind and the seismic forces; a lower resistance, the greater the rollover effect.
Thus, during a seismic load event or other type of high intensity loading, the cutting walls can be balanced towards one side or towards the other, and back independently, under the influence of the lateral or horizontal force. In any event, the cutting walls are offset from side to side around its point of attachment to the support of the base, i.e, on their respective ties to the support of the base. The independent wall roll allows for the damping of movement or dissipation of energy in the connectors, either connecting connectors between adjacent panels or joint connectors between a panel and its inner structural frame.
In connection with the problem of the dumping effect of the cutting walls, the effect known in the rubro as a rocking joint, this rotation concentrates the damage to the lower anchors, which causes the collapse of the wall and the tile to collapse. In turn, this rigid rotation greatly increases the lateral displacement of the floors, which increases the deformation of the floor (drift).
There are seismic design standards of buildings, where this industry defines the value of the seismic response factor (R) and the maximum value of the interfloor displacement of the structures (the interfloor displacement is the maximum horizontal deformation allowed between two floors in a seismic event); while, the R coefficient is a factor that basically allows to decrease the seismic forces with which it is designed such that the greater the greater, the greater the structure can be reduced and the cheaper the structure. Detailing a little plus this concept, the design force is said to be equal to the elastic force (which depends on the weight of the structure and its rigidity) starting from the R Value, ie:
Design force=elastic Force/R
Thus, the greater the Value of R, the lower the design force.
In highly seismic zones there are very demanding standards of seismic building design, which makes the CLT and similar wood structures to have a very low seismic response factor (R), implying that the forces with which a building must be designed will be greater and therefore much more expensive. It is also possible that the maximum value of the allowed interfloor displacement is very discrete (only a 2 percent in highly seismic countries) which indirectly forces the wall systems to be very rigid in order to meet this requirement. This is a non-minor problem in conventional wooden structures, because they are more flexible. Given the relative low capacity in axial loading of conventional wooden walls (frame type type), it occurs that buildings constructed with wood must employ a large number of walls.
The main difficulty of CLT walls is the problem of rigid body rotation caused by its flexible structural nature, which is defined as being rigid enough to resist large seismic forces, so that a building with this type of prefabricated walls completely based on The CLT would involve the use of a high amount of walls, facing the system.
Throughout the foregoing, there is a need for a cutting wall system that allows for medium height buildings in wood for highly seismic zones, achieving increasing the reduction factor of the Seismic design R for construction with wood; so that if the axial loading capacity is increased with respect to conventional wooden walls using the CLT, the amount of cutting walls necessary and significantly reducing the construction costs can be greatly reduced.
Thus, the present invention is directed to a cutting wall system with a functionally integrated hybrid configuration of mass wood panels against CLT laminated and an inner frame of another material different from that of said panels, wherein said structure exhibits a high capacity to resist lateral load, greater rigidity, greater ductility and the ability to dissipate energy than conventional wooden panels, has reduced effect of in addition, the lateral displacement of the floors is significantly decreasing and decreasing the seismic forces with which it is designed, makes it economically competitive.
The present invention relates to a hybrid cutting wall system for the construction of massive wooden buildings of more than two floors in seismic zones, which exhibits a ductile behaviour, rigidity and reduced rollover effect against a lateral load caused by destructive natural events, such as collisions or strong winds.
The invention is a cutting wall system which, using massive wood as one of its essential components, allows to reach a height of buildings of more than 2 floors with a lower number of walls than that which require other structural wooden systems, with increased ductility and ability to dissipate energy, without rigid rotations that concentrate the damage to the main anchors, and economically competitive.
The present invention is intended to propose a rigid cutting wall system and highly resistant to seismic loads, based on mainly a hybrid structure of massive wood panels and an inner frame formed by other materials other than the mass wood, wherein both the frame and the wooden panels act concomitantly as a single system.
It is another object of the invention to provide a cutting wall system having a high concentrated ductility in a high energy dissipation effect of the system, achieving that the load is distributed evenly along the entire perimeter of the cutting wall.
Still another object of the invention is to provide a cutting wall system which allows for a significant reduction in the rollover effect, avoiding the lifting and displacement of the walls, resulting in a greater stiffness and reduction of the maximum value of the interfloor displacement.
Another object of the invention is to provide a cutting wall system which allows to reduce rehabilitation costs subsequent to the seismic event, achieving that the integrity is not compromised in damage to the gravitational load bearing elements.
Thus, the present cutting wall system comprises a hybrid structure, with an articulated inner frame and massive wooden outer panels joined to both sides of the frame, forming a sandwich type structure, wherein the panels are joined to the frame by means of individual power dissipating connectors and where the inner frame comprises articulated connecting nodes between columns and solders conforming to the frame.
The cutting wall further comprises self-centering means consisting of post tensioned tensioners arranged along the wall and preferably only at the lateral edges of the wall, which are associated only to the columns or alternatively, associated with the columns and to the ends of the plates together. This relationship and the operation of the self-centering means will be explained later.
The inner frame is formed from columns and columns, where the columns are a set of vertical loading pillars which at least comprises two end side columns each located at each of the side edges of the cutting wall.
This column assembly may further include at least one intermediate column disposed between the two ends; the presence of this intermediate column will depend on the dimensions of the cutting wall, so that a shallow wall constructed with a single mass wooden panel could not need an intermediate column, rather if the wall is of a length where at least two wooden panels are required adjacent to each other, the intermediate column is arranged just where the joint joint is coincident between said adjacent panels, so that the energy dissipating connectors, which connect the wooden panels to the frame, have an anchoring support.
Each of the columns, are end or intermediate sides, are formed by a vertical body which may be solid or tubular, preferably of rectangular cross section, in which an upper minor face, a lower face, an outer longitudinal face, an inner longitudinal face and opposite front faces of each other are defined.
The end side columns, in particular, comprise means of passing said post tensioned tensioners, which lie inside and along its longitudinal axis. These pitch means may consist of longitudinal channels extending from the upper lower face to the lower face of the column, where this channel based solution is especially applicable in cases where the columns are made of a solid material, such as wood or concrete but in the case of being tubular bodies, such as a tubular steel profile, these columns need not add channels, but the tensioners freely pass through the cavity of the profile.
In alternative embodiments said side columns may comprise two, three, four or more longitudinal channels whereby they traverse said post tensioned tensioners.
Following the description of the structure of the inner frame, it is intended to comprise a top sill and a lower hearth, wherein each of them is formed by a horizontal body which can be solid or tubular, preferably of rectangular cross section, where lower lateral faces, an outer longitudinal face, an inner longitudinal face and front longitudinal faces opposite one another are defined.
These plates may comprise at least two transverse channels through which they traverse said post tensioned tensioners, so that in an alternative embodiment, said rods lack these channels, depending on the configuration and material of manufacture of the frame.
Thus, the configurations that the inner frame may take to depend primarily on the material used; in one embodiment of the inner frame with tubular steel profiles, the upper and lower plates acquire the total width of the wall, where the inner longitudinal face of said upper tile rests against the upper lower faces of the columns, while the lower faces of the columns are abutting on the inner longitudinal face of the lower tile.
In this case, since they are tubular profiles, the post tensioned tensioners freely pass within the profile conforming to the columns, but to traverse the plates and allow the tensioners to protrude from the upper and lower edges of the wall, such welds must include, in each end area, channels or transverse openings extending between its inner longitudinal face and the opposite outer longitudinal face.
This configuration of the inner frame may also be applied in the event that columns and containers are made of concrete, but in this case, since the parts are a solid body, it is necessary for said columns to comprise at least one longitudinal channel to allow the at least one post tensioned tensioner to pass, while the blanks must comprise, in each end area, transverse channels extending between its inner longitudinal face and its opposite outer longitudinal face.
In one embodiment of the inner frame made with columns and wooden flooring, given the flexibility of the material it is necessary to avoid crushing the upper edge of the columns, so that the plates are placed inside the side columns, thus, the latter are extended by the overall height of the wall. Specifically, the lateral minor faces of the upper deck lie in abutment with an upper area of the inner longitudinal face of the side columns, while the lower lateral sides of the lower hearth lie in abutment with a lower area of the inner longitudinal face of the side columns. This configuration of the inner frame may also be applied in the event that columns and containers are made of concrete.
In embodiments as just described, since columns and containers are solid bodies, in order to pass the post tensioned tensioners, the same treatment must be followed as the concrete pieces, ie, it must be provided with longitudinal channels in the columns to allow the tensioners to pass.
Thus, in any of the frame configurations just described, it is possible to add an intermediate column, which would have the same conditions as the side columns; although in a preferred alternative embodiment, the intermediate column does not comprise longitudinal channels for the tensioners, since that piece is practically not working.
In a final configuration of the frame, the assembly of the front and middle side faces form the support surfaces where the heat sealable connectors are anchored or fixed to each of the mass wooden panels with the inner frame. These energy dissipating connectors are individual elements together, which are installed throughout the perimeter of the panel. It is to be understood that if the wall comprises two massive wooden plates adjacent one side of the other, then the frame comprises at least one intermediate column where the heat sinks are fixed.
The mass wood panels, such as the CLT, are relatively rigid and therefore energy dissipation must be achieved by the ductile behaviour of the connections between different elements of the cutting wall. Therefore, high load strain capability connectors are needed that provide a high ductility or hysteretic energy dissipation to achieve acceptable performance of bulk wood panel buildings during events such as earthquake or large wind loads.
In the present invention, the heat sink connectors are of metal, of the type pin, selected from the group of pins, screws and nails. For attachment of the CLT panel to a steel frame, the connectors are preferably self-piercing pins. Thus, when the frame is wooden or concrete, the connectors are preferably threaded screws throughout its length. The function of the self-drilling connectors is to bracing the frame with respect to the seismic cutting force. The connectors are the weak point of the structure, so that the failure is intentionally produced there, which allows for much ductility until the ultimate failure is reached.
The essential feature of the system relating to its hybrid wall condition is given because, as mentioned above, the inner frame is of a material other than the material of the massive wooden panels that are fixed outwardly. Thus, the columns and columns of the frame are of a material that can be selected from materials such as steel profiles, post tensioned concrete or laminated wood.
In the case of being steel, they are tubular profiles, preferably with a resistance from ASTM a −36 to ASTM a −53 (240 to 365 MPa). If they are concrete, they preferably comprise a compressive strength in the range of 20 to 35 MPa, where the end side columns are of post tensioned concrete. While if they are wood, they are laminated, with a strength of the range between 1.3E and 1.55 The invention is characterised in that it is preferably made of LSL (rolled Strand) or MLE (Rolled wood) or LSL (Laminated wood) Laminated wood.
In terms of the outer panels of the cutting wall, they are structural wooden panels, preferably the panels are of bulk wood against laminated (CLT) with a thickness between 60 mm and 100 mm. It is important that the panels be thick, such as the CLT of thickness between 60 to 100 mm, because they offer much greater strength capabilities, since by connecting the CLT to the frame, the length of connector remaining within the CLT panel is greater than when compared to the embedded length thereof within a typical OSB Or plywood (plywood) board. The importance of using a thick panel, as in this case the CLT, makes its use not equivalent to the use of any board, because the CLT given its thickness of 60 to 100 mm is achieved by embedding the connector (screw, pin or long pin) inside it, and achieves that it forms a plastic joint at the interface of the frame with the CLT as the wall is deformed and the CLT Is slid relative to the steel frame.
But in terms of the requirement for a thick thickness of the outer panel, it is not attainable with any thick panel of massive wood available on the market, such as, for example, the LVL (Rolled Veneer light), which would appear Equivalent to the CLT.
The LVDT is produced by gluing wooden sheets together in a large molding, which is then serrated to the desired dimensions depending on the constructive application, however the plates are glued such that the direction of the fiber or grain of the wood is arranged in a single direction, the direction of the longitudinal or longer axis of the structural element, this implies that it only has an important strength in the longitudinal axis thereto fit is therefore only efficient for load stresses in a single direction.
In contrast, the CLT consists of several layers of wood boards stacked and glued together transversely or orthogonal (typically glued at 90 degrees), because it resists loading stresses in both the longitudinal direction of the element and the transverse direction, which determines that it can take cutting loads, and not only the axial directions. If it is thought in walls of both materials in a building, the LVL walls can only take up for example vertical axial loading of the structural weight, rather the CLT walls can take both loads, vertical and horizontal by wind or sism. Accordingly, they are not intended to be technically equivalent materials, because the CLT addresses another structural need; in this sense the CLT may not Be replaced by the LVDT for an application as the proposal in this invention since the same result would not be achieved.
The frame materials connected to the CLT generate lower crush strength and regulate the frangible effect that can cause a traditional CLT wall. The utility of the LVDT and other materials is to coordinate and reinforce the stress produced at the joints. Bulk woods Such As GLT (Glulam), LSL microlaminated woods, LSL Are Materials that counteract the side loading effect in a single direction, rather than in the other direction are weak. The wood in general has much greater strength and rigidity in the direction of the fibers. The CLT panels have fibers oriented in both directions within the plane.
Given the foregoing, the invention proposes this sandwich cutting wall structure to provide improved seismic performance. The elements of the wall frame support the axial load, also the stress between the CLT panels connected to the frame generates greater resistance to cutting. The above depends on the type of joints to which the wall truss is connected, ie, the joints between columns and solders.
Therefore, another of the essential characteristics of this cutting wall system is that the inner frame is articulated, which is given because the points of attachment between welds and columns are articulated node type assemblies, consisting of a normally pivoting mechanical attachment means that allows for assembly with relative movement in a plane between said columns and said plates.
By arranging this type of joints in the structure of the inner frame, it is achieved that the rigidity and lateral strength of the wall is dominated by the outer panels of massive wood.
This allows a master prediction of stresses in the components and especially at the joints, so that the structural design and its experimental response can be accurately predicted with great precision.
The connection of the articulated joints remains in an elastic regime, limiting the rigid body displacements. Thus, the predominant deformation for non-limbed walls is clearly shear so that the capacity and rigidity can be assumed proportional to the length of the wall.
If the columns and welds are of steel profiles, the mechanical attachment means conforming to the articulated nodes preferably consists of a pair of rigid support plates parallel to each other traversed by a transverse connecting pin.
If the columns and tanks are wooden, then the mechanical attachment means conforming to the articulated nodes preferably consists of a support lug attached to the columns, and on which the ends of the plates are seated. The plate can be fixed to the column by means of a diagonal pin so as to permit articulated movement between them.
If the columns and containers are of concrete, then the mechanical attachment means conforming to the articulated nodes may consist of a seat bracket projecting laterally from the columns, forming integral part thereof, as a single piece or as an added part, and on the bracket the ends of the concrete solders are seated, and adding a pin allowing relative movement between the pieces, in a single plane.
Another of the essential characteristics of this cutting wall system are the self-centering means, which allow the structure of the wall to acquire rigidity in an elastic regime which reduces the lifting effect of the wall, decreasing the feasibility of rocking laterally, and in turn allows the structure to be received after receiving a high lateral load stress, the structure is restored by acquiring its original position.
The self-centering means of the proposed cutting wall consists of non-adhered tensioners whose position goes to the height of the cutting wall, allowing an elastic attachment of the wall with a foundation or other wall stacked on one another in a coplanar position.
These tensioners comprise a lower end and an opposite upper end, where the lower end may be anchored and embedded in a foundation, which happens in the bottom or base cutting wall in a building; or alternatively, the lower end is axially adjustable to a wall connector between walls allowing for the postulated adjustment of the lower end of an upper wall stacked on the upper end of a bottom wall.
Therefore, the upper end of the tensioners can be fixed, but in an axially adjustable manner, to a wall/wall connector, which allows for the postulated adjustment of the lower end of an upper wall stacked on the upper end of a bottom wall; or said upper end may also be fixed axially, axially adjustable, to an anchor plate located on the upper edge of a wall, on the base to which the tensioner is post assembled.
The tensioners may be non-stick, spun steel bars with adjustable fasteners at their ends of the anchor plate type, or may be toron, non-stick, wedge shaped, wedge and anchor plate type steel cables.
In an exemplification of the assembly of two cutting walls stacked together, according to the present invention, it would be seen that a first cutting wall is disposed on a foundation and, for example, the wall comprising an inner frame of steel profiles, wherein the upper and lower plates extend along the entire width of the wall, then the lower tile of this first wall has simple attachment means with said foundation, such as anchor bolts distributed along it; thus, the side columns contain inside the self-centering tensioners, where the lower end thereof is concreted to the foundation and the opposite upper end is attached to a coupling connector which allows for the axial connection between said tensioners and at the same time between the first wall and the second wall disposed stacked on the first.
Thus, this second wall is mounted in a coplanar manner to the first, sill with the sill, allowing the tensioners of the first wall to extend towards the second from the nipple connector, where the upper end of the tensioner is fixed to the upper edge of the second wall in an anchor plate. Alternatively, in low height buildings, the tensioners could be continuous elements from the foundation to the upper edge of the top wall, regardless of the coupling of the coupling between walls. On the other hand, the walls may account for lateral anchoring means of the key type of cutting.
In operation, the frame structure is subjected to a permanent elastic rate which is stiffened with the structural involvement of the wooden panels once they are connected to the frame by means of the heat sink connectors, wherein these wooden panels serve the function of bracing the load elements of the inner frame, in addition to meeting the resistance to axial load function in cooperation with the same frame, both elements acting as a single system.
The desired effect, within the combination of the CLT materials in the outer panels; steel, concrete, LSL or LVL, in the Inner frame, together with the joints between the columns and solders conforming to the frame, plus the post tensioned tensioners located at the end edges of the wall, which in conjunction with the structure in an elastic regime; rather the energy dissipating connectors, allow for a ductile behaviour of the wall and at the same time rigid in comparison to the usual walls constructed of wood in general.
Thus, it is possible to describe more precise mode, how it is the behavior of each of the cutting wall components that is reason of the present invention: the CLT panels provide rigidity and lateral strength, subjected to simple cut stresses; the inner frame serves as a mechanism that allows the lateral load of the floor to be translated to the wooden panels, where their articulated nodes allow the frame to move laterally without opposition, the entire strength and stiffness being attributed to the outer panels of wood. On the other hand, the post tensioned tensioners prevent the lifting of the rigid body on the driven side of the wall, and in conjunction with the anchors of the lower sill, also prevent lateral displacement of the wall; the heat sink connectors which join the outer panels with the inner frame permit the bracing action of the CLT panels, and function as the weak part of the system in such a way that they prevent the breaking of the panels, frame or other components.
In the cutting wall system of the present invention, the deformation does not occur by tipping of the wall but by the cutting of the panels, and especially the cut in the connectors which join the panels to the inner frame. Said cutting deformation is much more advantageous because it allows to avoid additional deformations of the rigid body and in particular causes the capacity and rigidity of the wall is linearly proportional to its length, resulting in a much more predictable and controlled mechanical behaviour.
Another advantageous property is that a void intermediate space is achieved between the two CLT panels where the thermal insulation can be placed in the same manner as in a platform frame. In this system it is possible to put the insulation inside, while in walls made entirely of conventional CLT, screws and a termination must be installed to fix the insulation outside, since when a solid board is not possible to put the insulation. Another greatly notable advantage of this system is that it is possible to place the installations (plumbing, electricity, etc.) inside the wall, as well as the platform system. In the conventional CLT the installations are much more complicated to incorporate into the walls.
This system is cheaper than a conventional wall. In general, the CLT walls are sized according to the seismic load to be supported. In this way, the following example may be shown based on the Chile seismic Design Standard:
In a conventional CLT wall
a) the next volume of wood is occupied: 100 mm thick, 2.4 m high and 2.4 m wide=0.576 m3 of wood.
b) the typical resistance is 75 KN.
c) that is to say 75 KN/0.576 m3=130 KN of strength per m3 of wood.
d) the above is regardless of the reduction factor of the seismic response. Now well, considering that for the Conventional CLT R=2, it is given that the design force that the wall is able to resist is 130×2 (=R)=260 KN/m3. That is, if it is to resist a force of 260 KN in a CLT building, the Chilena NCh433 is allowed to reduce the force by 260/R=130 KN, which implies that it can actually resist 260 KN of lateral force (seismic) per m3 of wood that would occupy.
e) the anchors that are required are typically two lock down pins and four keys (cut angles).
In the present invention of wall with CLT
a) 2 plates of 60 mm=120 mm thick, 2.4 m high and 2.4 m wide, i.e, 0.691 m3 of wood are typically occupied. Assuming square feet of cross section laminated wood, 24 cm×9 cm and a total length of 10.8 m (2 sols of 2.4 m and 3 feet right of 2 m) we can take up to occupy 0.24×0.09×10.8=0.23 m3 of wood in the inner frame. That is, it would be occupied by occupying 0.691 M3 in CLT+0.23 m3 in laminated wood=0.921 m3 of wood per wall.
b) the typical resistance is 220 KN.
c) 220 KN/0.921 m3=239 KN/m3 of wood are obtained.
d) considering that it is more likely that the R=5.5 as the platform frame (actually being modifying The R of the platform frame by 6.5), we obtain that 239×5.5=1315 KN of lateral force can resist each m3 of wood.
e) the anchors required are typically 2 steel cables and several anchoring bolts.
From the foregoing it can be concluded that, in one way, that with the conventional system it can typically be withstood 130 KN per m3 of wood being occupied, while with the present invention it can be able to withstand 239 KN per m3 of wood being occupied, ie, the new system would allow to resist an 84% more force per m3 of wood used (almost double). However, the above is regardless of the fact that the construction standards (eg, the chilena NCh433 standard) allow to increase the force that can resist a wall if it is ductile.
Assuming that the present invention can occupy the R factor of a conventional platform frame, the system could withstand a force of 1315 KN per m3 of wood, while a conventional wall (with much less ductility) could resist 260 KN/m3, i.e, the invention in practice should be able to resist a more. This implies that a building with this system would require only ⅕ (20%) of the types of wood requiring a conventional system in walls. The costs of the slabs are typically 50% of the coarse, and the cost of the walls is the other 50%, which implies that the building should occupy 100% wood in slabs and 20% wood in walls, i.e, the costs of the building as to the wood should be as 60% of a conventional building (so that it is effectively much cheaper).
The above is only considering the costs of the wood, but the joints must also be considered. The hold down buttons that are to be employed in the conventional CLT are very expensive (the Sizes XXL are required), while in this system steel cables would be employed. With respect to the cutting keys of a conventional wall, these are clearly more expensive than the anchoring bolts used in this system.
Throughout the above, it is estimated that the prices of the anchors in both systems are similar. Moreover, the system of the present invention employs more screws, nails or bolts, as compared to the conventional system, that is to attach the boards to the inner rigid frame. These costs depend on the specific connector employed, but for example the large nails are very inexpensive. Throughout the foregoing, the proposed system is clearly much cheaper.
The joints may be somewhat more expensive (by the number of nails/screws to be used) but the anchors are nearly the same. However, the volume of wood that would be occupied would be much less. In particular, the use of more nails is used to be much more split to the material, and that makes it easier.
A detailed description of the invention will be carried out in conjunction with the figures which form an integral part of this embodiment, wherein:
With reference to the figures which form an integral part of this embodiment, and thus as illustrated by way of example in
The invention comprises an inner frame (100) with hinged (120) connecting nodes between columns (120) and solders (130), to which the outer mass (200) panels are joined at both sides by means of individual energy dissipating connectors (300), wherein the frame (100) comprises post tensioned self-centering means (400), which in conjunction with the articulated nodes (110), the outer mass wooden panels (200) and the individual energy dissipating connectors (300) they allow the cutting wall (1) to behave in a ductile manner and with reduced rollover effect against a high lateral load.
Taking as example,
Now, in reference to
As shown in
Alternatively, the mechanical attachment means may consist of a support lug (not shown) attached to the inner longitudinal faces of the columns, on which the ends of the plates are seated. Yet another alternative may consist of a seat bracket (not shown) projecting laterally from the columns, on which the ends of the plates are seated.
Now, in abutment with that illustrated in
As best illustrated in
The lower deck (132) of the lower wall (1) can be attached to the foundation (A) by means of anchoring bolts (E), which are the same with which the lower wall (132′) of the top wall (G) is attached to the top sill (131) of the bottom wall (1); additionally, the walls (1), (G) can consider means of lateral fixing of the key type of cutting (EF).
As seen in
The inner frame may take different configurations depending primarily on the material used; in one embodiment of the inner frame with tubular steel or concrete profiles, as illustrated in
In another embodiment of the inner frame, as illustrated in
As seen in
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CL2019/050111 | 11/5/2019 | WO |
