Failure Mode Analysis Of Huge Steel Frame Structures

As the growth of city population and increasing of building height, building's horizontal load, vertical load and overturning force moment is more and more big. What's more, higher standards of the internal space are used in modern architecture, such as buildings used for exhibitions, cultural activities, and so on. To meet the construction of a new situation and the requirements mentioned before, huge steel frame structures came into being. Because more and more huge steel frame structures are applied in civil engineering, it is significantly important to improve seismic capacity of structures by optimizing the failure modes of structures.Methods of failure modes analysis and improvement of huge steel frame structure failure modes are studied in this paper, which can increase integral seismic capacity. Main research contents are as follows:1. A huge steel frame structure has been designed in this paper. Two more structures are created by changing locations or height of giant beam.2. Based on nonlinear and elastic-plastic pushover analysis of three huge steel frame structures by using some finite element software, failure modes of different huge steel beam locations or heights are obtained. When the loads are fixed, there is only one structural failure mode for each structure. By comparing maximal story drift angle and base shear of every structure failure mode, taking into account of yield brace in pushover analysis, optimal structure form of huge steel frame structure can be found.3. Some normal brace which is failed of optimal structure form is replaced by buckling-restrained brace and structure failure mode of new structure will be compared with existing failure mode. Repeat this progress over and over again, the failure mode of huge steel frame structure is changing and integral seismic capacity is improving. Some new structures are got before all braces are taken place by buckling-restrained braces, which include a best structure.4. Nonlinear time-history analysis is applied on a series of new structures, by using two seismic waves which peak acceleration is increasing step by step. According to displacement overrun failure criterion and structure instability failure criterion, integral seismic capacity of structures is obtained. Verification of the optimal structure from pushover analysis can be performed by comparing each structure's integral seismic capacity.The results are as follows: enlarge the height of giant beam can improve structure integral seismic capacity best; adoption of buckling-restrained brace has changed huge steel frame structure's failure mode, and improved both elastic limit and integral seismic capacity; when failure brace is replacing by buckling-restrained brace step by step, huge steel frame structures will achieve good balance between economy capability and integral seismic capacity.