Mini Review

Research Progress and Development Direction of Buckling Restrained Energy Dissipation Brace

Peng Sun1*, Ruofan Shi1, Yifan Gu1 and Yuying Lin1

1Department of Civil Engineering, Shandong Jianzhu University, China

Submission: November 16, 2019; Published: December 16, 2019

*Corresponding Author: Peng Sun, Department of Civil Engineering Shandong Jianzhu University, Jinan 250101, China

How to cite this article: Peng Sun, Ruofan Shi, Yifan Gu, Yuying Lin. Research Progress and Development Direction of Buckling Restrained Energy Dissipation Brace. Civil Eng Res J. 2019; 9(4): 555768. DOI: 10.19080/CERJ.2019.09.555768

Abstract

This paper expounds the composition and basic principle of buckling resistant energy dissipation brace. According to different manufacturing processes, it mainly introduces concrete restrained buckling restrained brace, all steel buckling energy dissipation brace and assembled buckling energy dissipation support. The hysteretic behavior, low cycle fatigue performance and energy dissipation performance under repeated tensile and compressive loads were analyzed. Through summarizing the previous research results, the problems in the research of buckling resistant energy dissipation brace are pointed out, and the suggestions for future research are given.

Keywords: Buckling brace; Design theory; Experimental research; Hysteretic performance; Energy dissipation performance

Mini Review

Common bracings can improve the lateral stiffness of the structure and reduce the lateral displacement of the structure under small earthquake. But under strong earthquake, common bracings are prone to buckling and the energy dissipation capacity after buckling is poor, resulting in structural damage or even collapse. In order to solve this problem, many scholars at home and abroad have researched for many years and developed a kind of brace which can prevent compression buckling, that is, buckling resistant energy dissipation brace. Buckling resistant energy dissipation brace is mainly composed of steel inner core, outer restraint unit and unbonded material or air gap between the two parts [1], as shown in Figure 1. Buckling resistant energy dissipation brace effectively solves the problem of compression buckling of ordinary brace under rare earthquake and has the dual functions of ordinary brace and metal energy dissipation damper. Among the three components of the buckling proof support, only the steel inner core bears the axial force. The external restraint unit restricts the bending deformation of the steel inner core through its bending bearing capacity and bending rigidity, to prevent the overall or local buckling of the support when it is compressed. There is a clear division of work between the steel inner core bears and external restraint. The unbonded layer or air gap between the inner core and the outer constrained component is used to reduce the friction between them, and ensure that the axial force of the support is only borne by the steel core, so as to give full play to the superior deformation ability of the steel. This kind of structural setting of buckling resistant brace realizes that the brace has similar bearing capacity in compression and tension, and the brace can fully yield and consume energy in the whole section of the core energy dissipation section without large lateral bending deformation, which is the working principle of buckling proof brace.

In recent years, with the construction of more and more highrise and super high-rise buildings at home and abroad, buckling braces have been used in more and more practical engineering structures because of their excellent energy dissipation and shock absorption performance [2]. The types and design theories of buckling braces have also made great progress. According to different fabrication processes, the buckling restrained energy dissipation brace can be divided into the following categories:

a. Concrete restrained buckling restrained brace. In 1976, Kimura et al [3] conducted an experimental study on the support with square steel tube filled with concrete as the peripheral restraint element and steel plate as the core element. The stable hysteretic curve was obtained. Meanwhile, the influence of mortar strength index and unbonded coating on the supporting performance were pointed out. Mochizuki et al. [4] wrapped concrete on the outside of the ordinary support and added steel bars into the concrete. A layer of unbonded material was set between the support and the concrete, and the static reciprocating test was carried out on it. During the test, the concrete cracked, and the support buckled. The results show that the cracking of concrete leads to the serious decrease of flexural rigidity of lateral restraint, and the brace can’t show excellent hysteretic performance [4]. Nakamura et al. carried out low cycle fatigue test on full-scale concrete-filled steel tubular (CFST) external buckling brace, and its inner core section types were “one” type and “ten” type. The results show that the low cycle fatigue performance of “one” shaped inner core is better than that of “cross” shaped inner core, and the cross shaped core is prone to torsional buckling failure.

b. All steel buckling energy dissipation brace [5]. Wu Jing et al. [6] conducted an experimental study on high performance buckling restrained braces with angle steel spliced cross shaped solderless cores. The results show that the core parts of the cross section BRB spliced by the solderless core angle steel fully yield under tension and compression without buckling failure of the support and have very stable hysteretic performance. The hysteretic curve is always full and stable before the failure of the core parts, without obvious degradation or sudden increase of strength and rigidity. The total energy dissipation value of the specimen is much higher than that of the cruciform core BRB formed by direct casting and that of the cruciform core BRB welded with stiffener at the end. The cumulative plastic deformation value of the angle steel before fracture far exceeds the requirements of the specification, which has good low cycle fatigue performance [6]. Zhou Yun and Deng Xuesong put forward the concepts of “the local weakening of core element is equivalent to the strengthening of other parts” and “fixed point yielding”, and designed the open hole triple steel tube buckling energy dissipation brace, and carried out the finite element simulation and hysteretic performance test of the buckling energy dissipation brace. The results show that: after the local weakening of the core steel tube, the triple steel tube buckling energy dissipation brace can achieve “fixed-point yield”, which can effectively avoid the early failure of the end; the hysteretic curve of the open-hole buckling energy dissipation brace is full and symmetrical, which has good energy dissipation performance [7]. Pan Peng et al. conducted an experimental study on the energy dissipation performance of full steel buckling braces. The results show that: the structure of the all steel buckling brace is reasonable, the hysteretic curves of all specimens are stable and full; the core material characteristics and the length of the brace have a great influence on the energy dissipation performance of the buckling brace [8] .

Assembled buckling energy dissipation support. The earliest reinforced concrete prefabricated buckling brace was proposed by Inoue et al. and its peripheral restraint members were composed of two prefabricated reinforced concrete slabs and connected by long high-strength bolts. Prefabrication of reinforced concrete is more suitable for industrial production with controllable precision, but it still can’t solve the problem of cracking of peripheral concrete under the lateral extrusion pressure of the core [9]. Yukun Ding conducted an experiment on a new type of steel plate buckling restrained support combined with reinforced concrete slab to study the structural details of lightweight composite steel plate and the ability of reinforcement to improve the impact shear of concrete [10]. The results show that, compared with the traditional reinforcement, the perforated channel steel can effectively prevent the punching shear damage of the concrete slab. In addition, the slab can be easily assembled and disassembled to observe and replace the support, and can be reused, saving resources. Zhou Yun et al. proposed a steel-plate assembled buckling-restrained brace (PABRB). All parts of PABRB are assembled by steel plates while the core unit is weakened by perforating in order to yield at desired and multiple locations and the restraining ends are strengthened to prevent local buckling [11]. At present, in scientific research and engineering application, the low yield point steel with stable yield strength and good ductility is generally selected as the support steel core, which can provide certain additional damping and improve the seismic performance of small and medium earthquakes. However, low cycle fatigue fracture may occur under the action of large earthquake or super large earthquake. Adding damping is not conducive to the seismic safety of the structure. At the same time, even if the steel is not fractured, the accumulation ofplastic damage can’t provide the required lateral stiffness for the structure under large earthquake, which will lead to the collapse of the structure due to the interlayer deformation exceeding the design displacement limit. Therefore, how to ensure the buckling support to continue to play its working performance under the action of large earthquake or super large earthquake is the key problem to be solved urgently.

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