BACKGROUND OF THE INVENTION
Connectors are used to fasten attachments to buildings. For reinforced concrete structures, headed stud profiles with profile bolts may be used. Headed stud profiles consist of headed studs either forged or welded to C-profiles which are cast flush in the reinforced concrete structure and allow, after stripping of the formwork, the installation of matching T-bolts, aka profile bolts. The profile bolts are then used to fix baseplates of attachments, for example structural beams and columns or mechanical and electrical components.
The connectors are designed to carry an anticipated design basic load. The anticipated load may be exceeded particularly in case of explosions as well as unusual strong storms and earthquakes since it is uneconomical to design the connectors for the maximum credible load with a low probability of occurrence. During such unlikely event, however, the connectors may be overloaded. The overloading may damage the concrete structure due to hardly repairable concrete breakouts or the attachment with high risks for assets and persons.
BRIEF DESCRIPTION OF THE INVENTION
The invention provides for a technology to increase the overall capacity of the connectors and to sacrifice parts of the connectors to protect structure and attachment from damages beyond repair. This protecting connector is easy to manufacture, install, and maintain.
A first aspect of the invention relates to a building comprising at least two building elements, wherein said building elements are attached to each other with at least one connector, wherein at least one connector comprises at least one free strain element, wherein at least one free strain element is dimensioned as a yielding part, wherein the free strain element exhibits yielding upon exposure to a predetermined excess force acting on the free strain element, wherein the predetermined excess force is higher than a standard force being calculated according to static and dynamic forces acting on the free strain element under normal environmental conditions (the design basic load). The predetermined excess force is calculated such that the yielding of the strain element occurs before components of the building elements and/or regions of the connector outside the free strain element experience irreversible damage under non-standard environmental conditions. As a result, if a building of the invention is exposed to non-standard environmental conditions in excess of the basic load, like earthquakes, explosions, or storms, the free strain element yields, thereby protecting the other components of the building. As a result, it will be possible to repair the building simply by replacing the yielded strain elements by new, unyielded strain elements.
In a second aspect the invention relates to erecting a building, wherein at least two building elements are attached to each other with at least one connector, wherein at least one connector comprises at least one free strain element, wherein at least one free strain element is dimensioned as a yielding part, wherein the free strain element exhibits yielding upon exposure to a predetermined excess force acting on the free strain element, wherein the predetermined excess force is higher than a standard force being calculated according to static and dynamic forces acting on the free strain element under normal environmental conditions (the design basic load).
In a third aspect the invention relates to a method for protecting a building against damage through excess forces acting on the building, the building comprising at least two building elements, wherein said building elements are attached to each other with at least one connector, wherein at least one connector comprises at least one free strain element, wherein at least one free strain element is dimensioned as a yielding part, wherein the free strain element exhibits yielding upon exposure to a predetermined excess force acting on the free strain element, wherein the predetermined excess force is higher than a standard force being calculated according to static and dynamic forces acting on the free strain element under normal environmental conditions (the design basic load). The method further comprises yielding of the yielding part upon action of an excess force on the strain element and/or on the building.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A and FIG. 1B show a cast-in headed stud profile with installed profile bolts. The baseplate of the attachment has a special design to allow a free strain segment of the profile bolt.
FIG. 2A and FIG. 2B show a cast-in headed stud profile with installed profile bolts. The headed studs are fitted with a bond breaker to allow a free strain segment of the headed stud.
FIG. 3 shows a cast-in headed stud profile with installed profile bolts where the free strain segments of profile bolt and headed stud may be tuned either by modifying the cross section or length.
FIG. 4 shows a cast-in headed stud profile with installed profile bolts. The conventional headed studs are replaced by double headed reinforcing bars to serve the same purpose.
FIG. 5 shows a cast-in headed stud profile with installed profile bolts. The conventional headed studs are replaced by reinforcing bars which may terminate straight, hooked, or headed as shown.
FIG. 6 shows a cast-in headed stud profile with installed profile bolts. The capacity is increased by separate reinforcing bars which may terminate straight, hooked, or headed as shown.
FIG. 7 shows a cast-in headed stud profile with installed profile bolts. The capacity is increased by U-shaped reinforcing bar loops touching to the headed stud.
FIG. 8A and FIG. 8B show the cast-in headed stud profile with installed profile bolts. The baseplate of the attachment has a special design to allow a free strain segment of the profile bolt. The profile bolt is connected with a counter nut to the headed stud profile and connected with ratchet device to the baseplate.
FIG. 9A and FIG. 9B show the same situation as FIG. 8 but the attachment is (over-) loaded in tension. The ratchet devise transfers the load to the profile bolt.
FIG. 10A and FIG. 10B show the same situation as FIG. 9 but the attachment is reversed loaded under compression. The ratchet devise slides along the profile bolt.
FIGS. 11, 12 and 13 show three alternatives to the same situation as FIGS. 8 to 10 show but the fuse is integrated in an adapter which is reversed loaded under compression. The ratchet devise slides along a part of the adapter.
DETAILED DESCRIPTION OF THE INVENTION
The invention will now be described with reference to the figures, which in the embodiment relate to protecting connectors capable to protect building structure and attachment from damages beyond repair.
The components shown have the following reference signs:
- (1) Concrete
- (2) Headed stud profile (2a) headed stud (2b) profile
- (3) Profile bolt
- (4) Baseplate
- (5) Attachment
- (6) Free strain segment/element in air
- (7) Free strain segment/element within bond breaker (grease, foam, or sleeve)
- (8) Reduced cross section of profile bolt or headed stud
- (9) Adjustable nut of profile bolt
- (10) Adjustable nut of headed stud
- (11) Double headed reinforcing bar as headed stud
- (12) Straight, hooked, or headed reinforcing bar as headed stud
- (13) U-shaped reinforcing bar loops close to the headed stud
- (14) Ratchet devise
- (15) Counter nut
- (16) Threaded stud
- (17) Frame
- (18) Tension rod
To this end, the overall capacity of the connectors is increased and parts of the connectors can be sacrificed in case of overloading due to explosions, storms, and/or earthquakes.
It is understood that the invention may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the invention to those skilled in the art. Indeed, the invention is intended to cover alternatives, modifications and equivalents of these embodiments, which are included within the scope and spirit of the invention as defined in the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be clear to those of ordinary skill in the art that the invention may be practiced without such specific details.
Referring now for example to FIG. 1 there is shown in the cross section (FIG. 1A) and side view (FIG. 1B) the headed stud profile (2), consisting of one or more headed studs (2a) and a profile (2b) cast in the concrete (1) of the building structure. One or more profile bolts (3) with washers and nuts are installed in the profile to fix the baseplate (4) of any attachment (5), for example an H-section of a steel structure. The baseplate of the attachment has a special design to offset the fixation of the profile bolts (3) with washers and nuts, allowing a free strain segment of the profile bolt (3).
In case of overloading, yielding occurs along the free strain segment in a controlled, planned, and designed manner. The yielding part acts as a fuse which is sacrificed to protect the concrete (1) and attachment (5) from damage beyond repair. Moreover, the yielding dissipates energy. The length of the free strain segment is typically eight times its diameter. The described functioning of the free strain segment under tension overloading holds in principle also for the following examples. But only if yielding occurs at the profile bolt (3), easy replacement of this consumed fuse is possible. If yielding occurs at some part of the headed stud profile (2), a new connection may be needed, yet concrete (3) and attachment (5) has been protected.
Also FIG. 2 shows in the cross section (FIG. 2A) and side view (FIG. 2B) the headed stud profile (2), consisting of one or more headed studs (2a) and a profile (2b) cast in concrete (1) of the building. One or more profile bolts (3) with washers and nuts are installed in the profile to fix the baseplate (4) of any attachment (5). The baseplate of the attachment has a conventional design but the headed studs have a bond breaker (7), for example grease, foam, or sleeves, allowing a free strain segment of the headed stud (2a).
FIG. 3 illustrates that profile bolts and headed studs may have both free strain segments and that the free strain segments may be tuned either by reducing the cross sections (8) or by modifying the length using additional washers below the nut of the profile bolt (9) and replacing the head by a conventional or special nut which can travel along the threaded shaft of the headed stud. The latter must be carried out either in the factory/stockyard before shipping or on site before casting concrete. In both cases, the nut may be locked by means of suitable adhesives or plastic deformation. The protruding end of the headed stud is obsolete and may or may not be cut.
FIG. 4 shows another alternative where the conventional headed studs are replaced by double headed reinforcing bars (11) with bond breaker (7). The double headed reinforcing bars are welded to the profile and serve the same purpose as the headed studs with a typical deformation ratio of head and shaft between 1 and 2, however, have larger head sizes with a typical deformation ratio of head and shaft typically between 2 and 3.
FIG. 5 shows another alternative where the conventional headed studs are replaced by reinforcing bars (12) with bond breaker (7). The reinforcing bars are welded to the profile and terminate straight, hooked, or headed as shown. The bond breaker not only defines the free strain segment but also increases the capacity since the load is transferred from the reinforcing bar into the concrete at a larger embedment depth.
Reinforcing bars (13) with bond breaker (7) may also be used separately from the headed stud profile as shown in FIG. 6. The additional reinforcing bars may terminate straight, hooked, or headed and increase the capacity of the connection in tension and shear by taking over load transferred indirectly from the headed stud profile via the concrete. The bond breaker not only defines the free strain segment but also increases the capacity since the load is transferred from the reinforcing bar into the concrete at a larger embedment depth.
Reinforcing bars (13) with bond breaker (7) may also be used touching the headed studs as shown in FIG. 7. The additional reinforcing bars have a U-shape and increase the capacity of the connection in tension and shear by taking over load transferred quasi directly from the headed studs. The bond breaker not only defines the free strain segment but also increases the capacity since the load is transferred from the reinforcing bar into the concrete at a larger embedment depth.
FIGS. 8, 9, and 10 show a cast-in headed stud profile in the cross section (FIGS. 8A, 9A, 10A) and side view (FIGS. 8B, 9B, 10B) with installed profile bolts. The baseplate of the attachment has a special design to allow a free strain segment of the profile bolt. The profile bolt is connected with a counter nut (15) to the headed stud profile and connected with a ratchet device (14) to the baseplate. The ratchet device transfers tension from the attachment to the profile bolt (FIGS. 9A and 9B) but slides along the profile bolt if the attachment is under compression (FIGS. 10A and 10B). This setup ensures that load can be transferred continuously even after reversed cycles, for example due to alternating wind suction and pressure or seismic excitation, causing yielding of the profile bolt. Different ratchet devices (14) are imaginable, for example thrust nuts (U.S. Pat. Nos. 9,163,655 and 6,007,284).
FIGS. 11 to 13 show three alternative solutions to the solution shown in FIGS. 8 to 10. The difference is that the fuse is integrated in an adapter. The ratchet devise (14) slides along a part of the adapter, for example a threaded stud (16). The ratchet devise (14) is connected, for example by means of frame (17), with the attachment, for example a tension rod (18). The adapter allows the loading not only in pure tension (FIG. 11) but additionally in shear transversal to the axis of the headed stud profile (FIG. 12) and/or in shear longitudinal to the axis of the headed stud profile (FIG. 13). It goes without saying that this concept requires the fuse, for example a threaded stud (16), is the weakest part along the load path. Moreover, adapters may be used without ratchet devises if this still serves the requirements.
Patent Application
20230417042
