Studies On Dynamic Characteristics And Seismic Response Of Reinforced Concrete Mega-frame Structures

Mega-frame structures combined with the main level structure and the second-dary structure.It has advantages as below:clear force transmission,well done integral performance,quickly going construction,less spending materials,and wide development perspectives to high-rise building or super high–rise building. Thus,it is valuable in theory and practically meaningful to study the dynamic characteristics and seismic response of mega-frame stuctures.According to finite element theory, this article gets reinforced concrete mega-frame structure models using the large-scale general-purpose structural analysis and design software SAP2000,and finishing modal analysis, response spectrum analysis, elastic time-history analysis and elastic-plastic time-history analysis.First,model analysis towards mega-frame structure was carried out,and then its natural vibration characteristics were checked.Then, response spectrum analysis and elastic time-history analysis were carried out to study on the changes of seismic response of mega-frame structures by the changes of major column's stiffness and major beam members'stiffness or layout of braces and entering different seismic waves. According to the results obtained:the effects are different on the seismic behavior by considering the changes of mega-column's stiffness and mega-beam members'stiffness;the major beam controls the horizontal displacements more obviously with more layers of braces;the major beam controls the horizontal displacements more obviously and drift angle is distributed more evenly when the major beam braces'layout are near the lower part of the structure; mega-frame structures have a good resistance capacity to multi-earthquake.Last, elastic-plastic time-history analysis was carried out to study on different braces models,the major beam's effects and the yield mechanism under infrequent earthquake, and involved mega-frame structures'capacity to prevent collapse during mega earthquake. According to the results obtained: the major beam truss-type uses"X"braces or"Λ"braces that is closer but different from"/\"to dynamic performance; the major beam truss-type controls the horizontal displacements obviously, the displacement curve of mega-frame structures is a type of flexure-sheer and the plastic hinge state accord with the overall yield mechanism and the energy dissipation capacity is good; from the perspective of improving the overall aseismic capacity of building structures, reasonable collapse failure mechanism and some suggestions for the design of the reinforced concrete mega-frame structure are provided.