Dissertation > Industrial Technology > Building Science > Building structure > Special Structure > Anti - shock structure,disaster prevention structures > Shock, isolation, and explosion-proof structure > Seismic structure

Analysis on the Mechanical Behavior and Application of Buckling Restrained Braces

Author SongJian
Tutor HuiKuanTang
School Xi'an University of Architecture and Technology
Course Structural Engineering
Keywords Buckling restrained brace (BRB) Ultimate bearing capacity Load-displacement curve Time history analysis
CLC TU352.11
Type Master's thesis
Year 2011
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Based on the finite element software, this paper studied the buckling restrained brace (BRB) of the yield capacity and ultimate capacity with the finite element method, and analyzed the influence factors of BRB. Meanwhile, the economic effects and seismic energy dissipation of the buckling restrained braced framework were studied in this paper.The section size and construction methods of the buckling restrained braces in the paper were used from the BRB specimens in the test. With the finite element software, the BRB space model was set up by a special way. Compared with the results of ANSYS and experimental, it showed that the finite element model fitted better with the test model, so the finite element model could be applied to further analysis.This paper analyzed the first three buckling modes of BRB, and the results showed that: the core produced the low to higher order buckling mode jumping under the constraints of the constrained bodies, showing a number of wavy bending deformation.The load-displacement curves and the stress, deformation of BRBs’various components were obtained by nonlinear buckling analysis. Also the practical theoretical formula of BRBs’yield strength and ultimate strength were got. The paper also analyzed the degree of increase of constraints bodies on the BRBs’yield capacity. The results showed that: the constrained bodies played a key factor on the BRBs’capacity.This paper analyzed the effects of the four influence factors on the BRBs’yield capacity, given the theoretical formulas and the recommendations of the influence factors, and then summed up the practical design process of BRB. These factors were the friction coefficient of un-bonded materials, constraints ratio, concrete strength and gap size. These theoretical formulas and the design process had some practical engineering values. This paper compared the steel volumes of both the BRB and the general braces. The results showed that: the steel volumes of BRB were always less than the general braces’under the different loads. As the axial load increased, the economic advantage of BRB was more significant: when the axial force was 225kN and 3000kN, the BRB could save 26% and 35% steel volume compared with the general brace.Using nonlinear time history analysis method, this paper analyzed the seismic energy dissipation of both the buckling restrained braced framework and the general brace frameworks under the frequent earthquake and rarely occurred earthquake by comparing the displacement of framework, power factor and energy distribution of the two frameworks. The results showed that: compared with the general brace, the BRB could play a more prominent role in reducing the interlayer displacement and consuming seismic energy.

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