Patent Application
20200362585
The present invention relates to the technical field of external force resisting members of structural engineering, in particular to a buckling-restrained brace with an L-shaped energy dissipation element, a building and an assembly method.
In a multistoried or high-rise building steel structure system, a frame is the most basic unit. A brace enables the steel frame to have higher lateral resisting stiffness and strength, so as to reduce the lateral displacement of the frame during earthquake and avoid or reduce the damage to non-structural members. A buckling-restrained brace overcomes the shortcoming of compressive buckling of the common braces, and offers enhanced energy dissipation capability, reduced difference in tensile and compression resistances and ease of computer modeling.
After the 1994 Northridge Earthquake and the 1995 Kobe Earthquake, the use of buckling-restrained brace substantially increased in new buildings and seismic retrofits of existing construction. Moreover, various types of high-performance buckling-restrained brace have been proposed. However, the existing types of ordinary buckling-restrained brace have the following limitations:
1) Cumbersome disassembly and replacement: an energy dissipation element of the buckling-restrained brace needs to dissipate energy from an earthquake. The energy dissipation will inevitably cause damage or rupture of the energy-dissipation element, so the energy dissipation-seismic effect of the buckling-restrained brace may be greatly compromised in the aftershocks or subsequent earthquakes. For the existing buckling-restrained brace, in particular to the buckling-restrained brace using mortar or other brittle non-metallic filling material filled in steel tubes to realize a buckling-restrained mechanism, after a major earthquake, if the damage to the energy dissipation element needs to be detected, an outer restrained member needs to be disassembled, which is troublesome to operate and can also cause the damage to the brace. Even if special technical means prove that it is necessary to replace the damaged buckling-restrained brace, the removal of the existing buckling-restrained brace and the installation of the new buckling-restrained brace may be onerous for many reasons, for example, limited workspace at the buckling-restrained brace ends, especially when a gusset plate connecting the buckling-restrained brace to the frame is completely or partially obscured by ceilings or other non-structural members. In addition, many existing common buckling-restrained braces are connected with the gusset plates of the connecting frames through welding seams, so that it is necessary to apply secondary welding to the gusset plates for replacing the whole braces. It is difficult to perform the secondary welding and ensure the quality. Furthermore, the thermal effect generated by welding can affect the mechanical properties of the gusset plates and reduce the bearing capacity and fatigue performance of the new braces.
2) Poor recyclability: a buckling-restrained brace with reasonable design should control the damage within the constrained yielding segments of the energy dissipation element, while the buckling-restrained members should always remain elastic. However, the buckling-restrained members in many traditional buckling-restrained braces are very low in reusability, which does not help achieving the sustainable design objects.
The present invention discloses a buckling-restrained brace with an L-shaped energy dissipation element which is simple to disassemble and replace and can reuse buckling-restrained members conveniently, a building and an assembly method. In order to solve the above technical problems, the present invention provides the following technical solution:
In one aspect, the present invention discloses a buckling-restrained brace with an L-shaped energy dissipation element, which is used as a brace for a frame structure and includes a telescopic inner restrained member, an outer restrained member sleeved outside the inner restrained member and the L-shaped energy dissipation element between the inner restrained member and the outer restrained member, wherein,
the inner restrained member includes a first steel square tube and a second steel square tube with the same length and outer section size, the first steel square tube and the second steel square tube are connected by insertion, and the ends of the first steel square tube and the second steel square tube are connected with the frame structure; the L-shaped energy dissipation element includes four L-shaped fuses, and two ends of the four L-shaped fuses are connected to the four right-angle sides of the first steel square tube and the second steel square tube by bolts, two slots/notches are formed in the middle part of each of the L-shaped fuses for forming weakened yielding segments, and the two ends are non-weakened non-yielding segments; and
the inner section of the outer restrained member is square, the outer restrained member covers the L-shaped energy dissipation element, and a certain gap is disposed between the outer restrained member and the L-shaped energy dissipation element. Further, the first steel square tube and the second steel square tube have the same size, the first steel square tube and the second steel square tube are connected by a male-male adaptor, the male-male adaptor is a steel square tube, stiffeners which are arranged outside surface and perpendicular to the planes of the steel square tubes are arranged at the middle part of the male-male adaptor, the outer section size of the male-male adaptor is smaller than the inner section size of the first steel square tube, one end of the male-male adaptor is welded or plugged into the first steel square tube, and the other end is plugged into the second steel square tube.
Further, each of the first steel square tube and the second steel square tube is 100-5000 mm long, the spacing between the first steel square tube and the second steel square tube is 20-500 mm, the gap between the outside surface of the male-male adaptor and the inside surface of the second steel square tube is 1-10 mm, and of the male-male adaptor plugged into the second steel square tube is 20-800 mm long. Further, bolt holes for connection with the first steel square tube and the second steel square tube are formed in the outer side parts of the non-yielding segments, the non-yielding section includes an unrestrained connecting segment provided with the bolt holes, an unrestrained non-yielding segment not provided with the bolt holes and not covered with the outer restrained member and a restrained non-yielding segment not provided with the bolt holes but covered with the outer restrained member, the outer restrained member covers the yielding segments and the restrained non-yielding segments, and the yielding segments are restrained yielding segments restrained by the inner restrained member and the outer restrained member.
Further, lifting pieces used for lifting the outer restrained member are fixedly arranged at the unrestrained non-yielding section in the lower parts of the L-shaped fuses; the non-weakened non-yielding segments are arranged at the middle parts of the L-shaped fuses for forming middle restrained non-yielding segments, and the length of each of the middle restrained non-yielding segments is greater than the spacing between the first steel square tube and the second steel square tube when the buckling-restrained brace deforms due to a maximum design tension capacity.
Further, the outer restrained member is formed by buckling four W-shaped steel plates, and the adjacent W-shaped steel plates are connected by the bolts;
or, the outer restrained member is formed by connecting two U-shaped steel plates which open in the same direction by the bolts;
or, the outer restrained member includes two U-shaped steel plates which are arranged opposite with each other and open in the opposite direction, and two steel plates are connected to the side faces of the U-shaped steel plates by the bolts;
or, the outer restrained member is formed by buckling two U-shaped steel plates, and the two U-shaped steel plates are connected by the bolts.
Further, the gap between the outer restrained member and the L-shaped energy dissipation element is 1-5mm, and a debonding material is filled in the gap. Further, transition regions between the adjacent two sections of the restrained non-yielding segments, the restrained yielding segments and the middle restrained non-yielding segments are arc lines, straight lines or a combination thereof.
In a further aspect, the present invention provides a building, including the above buckling-restrained brace with the L-shaped energy dissipation element.
In still a further aspect, the present invention further provides an assembly method of the above buckling-restrained brace with the L-shaped energy dissipation element, including:
step 1: welding or plugging one end of the male-male adaptor to or into the first steel square tube, and inserting the other end into the second steel square tube to form the inner restrained member;
step 2: adjusting the spacing between the first steel square tube and the second steel square tube, and connecting the unrestrained connecting segments of the L-shaped energy dissipation element to the right-angle sides of each of the first steel square tube and the second steel square tube by the bolts;
step 3: covering the L-shaped energy dissipation element by the outer restrained member, and connecting the components of the outer restrained member by the bolts. The present invention has the following beneficial effects:
Compared with the prior art, in the buckling-restrained brace with the L-shaped energy dissipation element of the present invention, two ends of the four L-shaped fuses on the L-shaped energy dissipation element are respectively connected to the four right-angle sides of each of the first steel square tube and the second steel square tube of the inner restrained member by bolts so as to be convenient to install and disassemble. The damage is concentrated at the yielding segments of the L-shaped fuses, the inner restrained member and the outer restrained member still remain elastic after an earthquake and can be reused, only the L-shaped fuses need to be replaced, and then the buckling-restrained brace can restore its energy dissipation function.
In order to enable the technical problems, the technical solutions, and the advantages of the present invention to be clearer, the present invention will be described in detail in conjunction with the drawings and the specific embodiments.
In one aspect, the present invention discloses a buckling-restrained brace with an L-shaped energy dissipation element, which is used as a brace for a frame structure (as shown in
the inner restrained member 1 comprises a first steel square tube 1-1 and a second steel square tube 1-2 with the same length and outer section size, the first steel square tube 1-1 and the second steel square tube 1-2 are connected by insertion, the ends of the first steel square tube 1-1 and the second steel square tube 1-2 which are away from each other are connected with the frame structure, specifically, elongated slots can be formed all around the outer ends of the first steel square tube 1-1 or the second steel square tube 1-2 and connected with gusset plates of the frame structure through connecting plates 1-3 or directly, as shown in
The L-shaped energy dissipation element includes four L-shaped fuses 3, and two ends of the four L-shaped fuses 3 are connected to the four right-angle sides of the first steel square tube 1-1 and the second steel square tube 1-2 by bolts respectively; the bolts here can be blind hole bolts meeting the design requirements or high-strength bolts with screw rods long enough; the cross section of each of the L-shaped fuses 3 is L-shaped and can be formed by cutting profile steel or formed by cold-bending cut steel plates without welding, which reduces the initial defects of energy dissipation elements and is beneficial for giving full play to the performance of steel products. When the first steel square tube 1-1 and the second steel square tube 1-2 on the L-shaped fuses 3 are connected by bolts, the bolts here can be blind hole bolts meeting the design requirements or high-strength bolts with sufficiently long screw rods, or the like; bolt holes are formed in the first steel square tube 1-1 and the second steel square tube 1-2 according to design positions and sizes; on the same side, the the bolt holes can be arranged in parallel or staggered, openings of the bolt holes can neither cause the mutual influence of the bolts, nor affect the relative motion of the first steel square tube 1-1 and the second steel square tube 1-2, the openings in the two parallel sides can be arranged in the same way the openings in the two perpendicular sides can be staggered, and the specific arrangement can be determined according to the actually adopted bolts.
Two alots/notches 4 are formed in the middle part of each of the L-shaped fuses 3 for forming weakened yielding segments 3-1, and two ends of the L-shaped fuses are non-weakened non-yielding segments 3-2;
the inner section of the outer restrained member 2 is square, the outer restrained member covers the L-shaped energy dissipation element, and a certain gap is disposed between the outer restrained member 2 and the L-shaped energy dissipation element. Compared with the prior art, in the buckling-restrained brace with the L-shaped energy dissipation element of the present invention, two ends of the four L-shaped fuses on the L-shaped energy dissipation element are respectively connected to the four right-angle sides of each of the first steel square tube and the second steel square tube of the inner restrained member by bolts so as to be convenient to install and disassemble as well as to replace the L-shaped energy dissipation element after an earthquake. During replacing process, it only needs to connect new L-shaped fuses to the inner restrained member by bolts without welding. When the buckling-restrained brace with the L-shaped energy dissipation element is installed, the first steel square tube and the second steel square tube of the inner restrained member are connected by insertion, then the four L-shaped fuses are connected on the four right-angle sides of the first steel square tube and the second steel square tube by the bolts, and finally, the outer restrained member covers the L-shaped fuses. When in tension or compression, the damage can be concentrated at the yielding segments of the L-shaped fuses, the inner restrained member and the outer restrained member still remain elastic after an earthquake and can be reused, only the L-shaped fuses need to be replaced, and then the energy dissipation-seismic function of the buckling-restrained brace can be restored.
Further, the first steel square tube 1-1 and the second steel square tube 1-2 are preferably the same (i.e., the same length, thickness and outer section), and are made of the same material. As shown in
It should be noted that, as shown in
Preferably, as shown in
Preferably, lifting pieces 5 used for lifting the outer restrained member 2 are fixedly arranged at the unrestrained non-yielding segment 3-2-3 in the lower parts of the L-shaped fuses 3; the lifting pieces 5 may be fixedly connected with the L-shaped fuses 3 by welding and in other ways; a plurality of lifting pieces 5 are provided, and are positioned in the same plane vertical to the lengthwise direction of the L-shaped fuses, as shown in
As the male-male adaptor 1-4 has small section size and a poor restrained effect at the spacing between the first steel square tube 1-1 and the second steel square tube 1-2 of the inner restrained member 1, the non-weakened non-yielding segments are preferably arranged in the middle parts of the yielding segments 3-1 of the L-shaped fuses 3 for forming middle restrained non-yielding segments 3-3; the length of each of the middle restrained non-yielding segments 3-3 is greater than the spacing between the first steel square tube 1-1 and the second steel square tube 1-2 when the buckling-restrained brace deforms by the maximum design tension capacity, so as to reduce the stress intensity and damage intensity here, thus controlling the plastic damage within the restrained yielding segments, which avoids high stress and damage concentration here caused by the premature occurrence of local buckling deformation, resulting in the premature fracture of the L-shaped energy dissipation element.
Each L-shaped fuse 3 sequentially includes the unrestrained connecting segment 3-2-2, the unrestrained non-yielding segment 3-2-3, the restrained non-yielding segment 3-2-4, the restrained yielding segment, the middle restrained non-yielding segment 3-3, the restrained yielding segment, the restrained non-yielding segment 3-2-4, the unrestrained non-yielding segment 3-2-3 and the unrestrained connecting segment 3-2-2 from one end to the other end.
In the present invention, the outer restrained member 2 has a restraint function to the L-shaped energy dissipation element; there are various structural forms of the outer restrained member 2, and some of them are described as follows:
A shown in
As shown in
As shown in
As shown in
The sequence of the above embodiments is only for the convenience of description, instead of representing the priority of the embodiments, and the outer restrained member 2 in the above embodiments is connected by the bolts respectively, which is simple to disassemble; furthermore, the outer restrained member should be consistent with the designed length of the restrained yielding segments, thus ensuring that the restrained yielding segments do not stretch out the outer restrained member in any case (especially bear the maximum design tension capacity).
As an improvement of the present invention, the gap between the outer restrained member 2 and the L-shaped energy dissipation element is 1-5 mm, a debonding material is preferably filled in the gap; the debonding material can be lubricating oil, soft glass or Teflon material and the like, and can also be selected flexibly according to specific situations, moreover, the non-bonding material can reduce the friction force between the L-shaped energy dissipation element and the inner restrained member 1 and between the L-shaped energy dissipation element and the outer restrained member 2 when the high-order buckling deformation of the L-shaped energy dissipation element occurs.
As another improvement of the present invention, as shown in
In a further aspect, the present invention provides a building including the above buckling-restrained brace with the L-shaped energy dissipation element. As the structure is the same as the structure above, it will not be repeated herein.
In still a further aspect, the present invention further provides an assembly method of the above buckling-restrained brace with the L-shaped energy dissipation element, including:
step 1: welding or plugging one end of the male-male adaptor 1-4 to the first steel square tube 1-1 (during welding, prefabricated in a factory), and plugging the other end into the second steel square tube 1-2 to form the inner restrained member 1;
step 2: adjusting the spacing between the first steel square tube 1-1 and the second steel square tube 1-2, and connecting the unrestrained connecting segments 3-2-2 of 4 L-shaped energy dissipation elements to the right-angle sides of each of the first steel square tube 1-1 and the second steel square tube 1-2;
step 3: covering the L-shaped energy dissipation element by the outer restrained member 2, and connecting the components of the outer restrained member 2 by the bolts.
The buckling-restrained brace with the L-shaped energy dissipation element of the present invention undergoes performance tests according to Shanghai Engineering Construction Standard Code for Design of High-rise Building Steel Structures (DG/TJ08-32-2008) (referred to as Shanghai high steel code), Code for Seismic Design of Buildings (GB50011-2010) (referred to as seismic code), Shanghai Recommended Application Standard of Building Products, Application Technology Code for TJ Buckling-restrained Braces (DBJ/CT105-2011) (referred to as TJ restrained brace code) and Technical Specification for Seismic Energy Dissipation of Buildings (JGJ297-2013) (referred to as energy dissipation code), and the tests are specifically as follows:
In the seismic code, the net length of the brace is defined as L; in the Shanghai high steel code and the TJ restrained brace code, strength degradation of the test pieces are required to be not more than 15% in three tensile and compressive tests at the displacement amplitudes of L/300, L/200, L/150 and L/100 in sequence; and in the seismic code, the energy dissipation code and the TJ restrained brace code, the strength degradation of the test pieces are required to be not more than 15% in 30 cycles at the displacement amplitude of L/150.
The basic parameters of the buckling-restrained brace with the L-shaped energy dissipation element are listed in Table 1. In the tests, it was assumed that the total length of the restrained yielding segments was 0.56 times the length of the brace. 30 cycles of constant amplitude loading with the displacement amplitude corresponding to L150 and incremental loading (increased once every three circles) with the displacement amplitudes sequentially corresponding to L/300, L/200, L/150 and L/100 were sequentially applied to the specimen B4. In constant amplitude loading process, the tensile strength degradation was 3.6% and the compressive strength degradation was 5%, and the compressive strength met the requirement of being within 15%. In the variable amplitude loading process, no obvious (more than 15%) strength and stiffness degradation occurred, meeting the requirements of the code. In Table 1, the cumulative plastic deformation (CPD) of each specimen was calculated according to the American Standard AISC 341-16 (AISC 2016), and the cumulative plastic deformation of each specimen exceeded the recommended lower limit of 200 given in AISC 341-16 (AISC 2016), wherein the CPD of the specimen B4 reached 2214.
In Table 1, the maximum compression/tension ratio β of each specimen was less than the upper limit 1.3 specified by AISC 341-16, being in line with the requirements of the code.
Moreover, as shown in
The above is a preferred embodiment of the present invention. It should be noted that, those skilled in the art can also make a number of improvements and modifications without departing from the principles of the present invention, and the improvements and modifications should also be regarded as being within the protection scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201710610892.0 | Jul 2017 | CN | national |
| 201720905586.5 | Jul 2017 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2018/092742 | 6/26/2018 | WO | 00 |
