Shaking Table Test of Structure With Reinforced Buckling Restrained Braces

Author(s):  
C. S. Tsai ◽  
Wen-Shin Chen ◽  
Kuei-Chi Chen

The traditional brace elements will buckle when subjected to severe earthquakes. Many researchers have been trying to overcome this disadvantage of the traditional brace element since 1970’s. Many types of braces have been developed without buckling under large compressive forces called the buckling restrained brace BRB, or unbonded brace. This type brace includes a steel core, a case that encases the steel core and brace projection, and can enhance both the stiffness and hysteretic damping of a structure to resist seismic loadings. Recently, some investigators have carried out the researches focusing on the procedure of designing buckling restrained braces, quasi dynamic testing and the methods of the connection between the buckling restrained brace and main structure. But, these results can not reflect the effects of the structure with buckling restrained braces during earthquakes. Therefore, the shaking table testing should be done to examine the effects of new BRBs on the seismic responses of a structure. In this study, the reinforced buckling restrained braces were installed on a three-story scaled steel structure in Feng Chia University to perform a series of shaking table tests. The test results illustrate that the new unbond braces provide good protection for structures during earthquakes.

2019 ◽  
Vol 23 (1) ◽  
pp. 37-50 ◽  
Author(s):  
Jihong Bi ◽  
Lanfang Luo ◽  
Nan Jiang

Dynamic equations are presented that have been deduced for a real-time dynamic substructuring shaking table test of an equipment-structure system, based on the branch mode substructure method. The equipment is adopted as the experimental substructure, which is loaded by the shaking table, while the structure is adopted as the numerical substructure. Real-time data communication occurs between the two substructures during the test. A real-time seismic energy calculation method was proposed for the calculation of energy responses, both in the experimental substructure and the numerical substructure. Taking a representative four-story steel frame/equipment model, real-time dynamic substructuring shaking table tests and overall model tests were executed. The proposed real-time dynamic substructuring shaking table testing method was verified by comparing the test results with shaking table test results for the overall model. The energy responses of each component in the equipment-structure system, using different connection types, also were studied. Changes in the connection types can lead to changes in the energy responses of the equipment-structure system, especially with respect to the equipment. The choice of the connection for the equipment-structure coupled system should take into account the operational performance objective of the equipment.


Author(s):  
C. S. Tsai ◽  
Wen-Shin Chen ◽  
Yung-Chang Lin ◽  
Chen-Tsung Yang ◽  
Ching-Pei Tsou

Since 1970’s, many types of braces have been developed without buckling under large compressive forces called the buckling restrained brace BRB, or unbonded brace. Recently, many investigators have made a lot of efforts to look into the behaviors of the buckling restrained brace under quasi-static forces, but few experimental results about shaking table tests of a structure with buckling restrained braces have been published. Therefore, in this study, a series of shaking table tests were carried out in the National Center for Research on Earthquake Engineering, and the issue is focused on observing the seismic responses of a full-scale three-story steel structure with multi-curved reinforced buckling restrained braces subjected to earthquake ground motions. Experimental results show that most column shear forces and displacements had been reduced by the RBRB devices. In addition, the absolute accelerations had also been favorably diminished during earthquakes. It can be proven that the proposed device is suitable for applications of seismic mitigation for structures.


2016 ◽  
Vol 20 (4) ◽  
pp. 641-657 ◽  
Author(s):  
Wei Li ◽  
Bin Wu ◽  
Yong Ding ◽  
Junxian Zhao

To prevent lower-order local buckling of H-section steel core, an improved type of buckling-restrained braces named buckling-restrained brace with H-section steel core was proposed by the authors. This article further investigates the effect of configuration details on seismic performance of buckling-restrained braces with H-section steel core and compares two half-wavelength calculation methods for higher-order local buckling of H-section steel core. First, quasi-static cyclic tests are described on two newly designed buckling-restrained braces with H-section steel cores and another buckling-restrained brace with flat steel core. Then, Bleich’s and Lundquist’s methods are reviewed for evaluating half wavelength of higher-order local buckling based on elastoplastic buckling theory of plates and compared with the test results of four buckling-restrained braces with H-section steel core including the two from a previous test. It is found from the test results that due to H-section steel core’s higher self-stability, the compression force fluctuation was not observed on the hysteretic loops of buckling-restrained brace with H-section steel core with even larger clearance but on the buckling-restrained brace with flat core. The buckling-restrained brace with H-section steel core was also advantageous over the buckling-restrained brace with flat core in terms of having lower compression strength adjustment factor β. A stopper in the middle of the core member and the gradual change of cross section of the core plate around the end of stiffeners could help to improve the fatigue performance of buckling-restrained braces. The test results also confirmed that Lundquist’s theory was more reliable for evaluating the half wavelength of higher-order local buckling for H-section steel core.


2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Lanfang Luo ◽  
Nan Jiang ◽  
Jihong Bi

This study investigated the real-time substructure shaking table testing (RTSSTT) of an equipment-structure-soil (ESS) system and the effects of soil on the seismic energy responses of the equipment-structure (ES) subsystem. First, the branch modal substructure approach was employed to derive the formulas needed for the RTSSTT of the ESS system. Then, individual equations for calculating the energy responses of the equipment and the structure were provided. The ES subsystem was adopted as the experimental substructure, whereas the reduced soil model was treated as the numerical substructure when the RTSSTT was performed on the ESS system. The effectiveness of the proposed testing method was demonstrated by comparing the test results with those of the integrated finite element analysis. The energy responses of the ES subsystem in the case of rigid ground (i.e., the ES system) were compared with those considering the effects of soil (i.e., the ESS system). The input energy responses of the ES subsystem were found to decrease significantly after taking the effects of soil into account. Differences due to the soil effects should be considered in the seismic design for the ES system.


2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Haibo Wang ◽  
Yongfeng Cheng ◽  
Zhicheng Lu ◽  
Zhubing Zhu ◽  
Shujun Zhang

Pillar electrical equipment is an important part of substations. The application of composite materials in pillar equipment can facilitate the improvement of the seismic performance of electrical equipment. In this paper, the test of elastic modulus and bending rigidity was conducted for individual composite elements in insulators and arresters, and the calculation formula for bending rigidity at the composite flange cementing connections was put forward. The numerical simulation model for the earthquake simulation shaking table test of ±1,100 kV composite pillar insulators was established, in which the bending rigidity value for the flange cementing part was obtained by the test or calculation formula. The numerical simulation results were compared with the earthquake simulation shaking table test results, the dynamic characteristics and seismic response of the model were compared, respectively, the validity of the proposed calculation formula for flange bending rigidity of composite cementing parts was verified, and a convenient and effective means was provided for calculating the seismic performance of composite electrical equipment.


2016 ◽  
Vol 11 (1) ◽  
pp. 97-105 ◽  
Author(s):  
Kuniyoshi Sugimoto ◽  
◽  
Kenji Yonezawa ◽  
Hideo Katsumata ◽  
Hiroshi Fukuyama ◽  
...  

Shaking table test of a quarter-scale 20-story reinforced concrete building model was carried out. Employed input waves were kinds of long period and long duration ground motion. Test results showed that structural slabs were fully effective for building strength, which could be expressed in detailed analysis using nonlinear FEM. However, the observed hysteretic damping after yielding was fairly smaller than the expected by the current design custom, which caused smaller and unsafe estimated response than that observed in the test.


2014 ◽  
Vol 11 (4) ◽  
pp. 357-364
Author(s):  
Hui Su ◽  
Jian Wang ◽  
Xinpei Jiang ◽  
Yang Tan

Based on the shake table test on "tie column-ring beam-cast-in-place slab" construction waste recycled brick masonry structure, a 1/3 scaled model of 4 stories is tested to analyze the seismic behavior of the multi-storey masonry structure. The test is conducted with EL-Centro seismic wave, Taft wave and artificial wave to simulate the damages observed and the seismic response under different earthquake levels. On the basis of test results, the seismic performance of the model is good and the overall structure could satisfy seismic fortification requirements in the region of intensity 8. At the same time, there was no obvious difference between this masonry structure and recycled aggregate concrete block masonry structure. The lintel of the door and window damage seriously. The base damages more easily than the superstructure. Masonry structure with construction waste recycled brick can satisfy the requirement of the masonry structure buildings in eight degree of aseismatic design area.


Author(s):  
Navaratnarajah Sathiparan

This paper discusses the shaking table test results of three PP-band (Polypropylene band) retrofitted quarter scale one-story masonry house models with different roof conditions. Better connections between masonry wall and roof connection are one factor to improve the seismic safety of the masonry houses. Past studies show that PP-band retrofitting improves the integrity of structural components and prevent the collapse of masonry structures during an earthquake. Although the effect of masonry unit type, surface plastering, the pitch of the PP-band mesh, PP-band connectivity in mesh and tightness of the mesh attachment to walls were studied by experiment program, the effect of the roof and its diaphragm connectivity on PP-band retrofitted masonry structure is nonexistent. Therefore, an experimental program was designed and executed for an understanding the effect of the roof and its connection on the dynamic behavior of the PP-band retrofitted box-shaped masonry house models. Results reveal that the PP-band retrofitted models with proper roof diaphragm improves the seismic behavior with respect to lateral drift, shear resistance and ductility.


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