| Reinforced concrete frame is a widely used structure all over the world, it isone of the basic structures which are widely used in the industrial cities and the fieldof high rise buildings. In recent years, because of many earthquake hazards manyreinforced concrete frames are destroyed seriously which cause lots of personalinjury, death and loss of properties. For example, the Wenchuan earthquake whichoccur in May12,2008, its magnitude is8and its maximum intensity is11degrees,the earthquake caused a total of nearly70000death, the direct economic loss wasnearly100billion Yuan, so it has far significance to analysis how reinforcedconcrete frame structure could resist the earthquake. The study found that the RCframe joints’ failure leads to local and even whole collapse of structures in manyearthquakes. In the past several decades, beam-column joints of reinforced concreteframes have been studied in experimental and theoretical aspects by many scholarsfrom many countries. Since the forces in the core zone of the joint are very complexbecause of its complex construction, the finite element simulation focus onreinforced concrete frame structure, the joints are usually regarded as rigid joints, soin the modeling stage, the joints could fail impossible, when calculation thestructure’s deformation, the joints’ deformation is also ignored, there is few studyabout that adding the joint model to the frame model (that means the overalldeformation also consider joints’ deformation besides beams’ and columns’deformation, even the structure could damage because of joints’ failure first). So it isextremely important and urgent that when we are studying the frame structure’sseismic analysis we consider the joints.In this thesis, in OpenSees system, introduction and numerical simulation onbeam column joints of reinforced concrete frames and the seismic performance ofRC frames which considering of joint models are thoroughly and carefully carriedout, the main contents are as follows:(1) Introducing the research status of the joint’s test and finite element modelwhich done by many scholars from different countries, then introducing the joint’sstress state in the earthquake, putting forward the constitutive model of joint’s corearea material and the method of confirming the parameters.(2) Basing on the modeling method in this thesis, a frame structure modelconsidering joints is built, then simulate a existing shaking table test which focus ona four spans and two stories frame structure, to check the frame structure modelconsidering joints is precise and viable.(3) Basing on OpenSees analysis software, elastic plasticity static analysis is conducted on the frame structure model not considering joints (joints are regarded asrigid joints) and the frame structure model considering joints, comparing andanalyzing the results which including the natural vibration period of structure, baseshear and top displacement relationship of the two kinds of structure. Thus we getthe conclusion, considering joints will decrease the structure’s stiffness, themaximum base shear and ductility will decline, too.(4) Selecting a typical earthquake record which is under rare status to performnonlinear time history analysis for frame structure model considering joints and theframe structure model not considering joints (joints are regarded as rigid joints),then comparing and analyzing the results which including floor displacement, thedrift between two floors, the order of the plastic hinge’s appearance of the two kindsof structure. Finally, through IDA analysis of the two kinds of structure models,until the maximum seismic dynamic the two kinds of structure can obtain. Thus weget the conclusion, the assumption that not consider joints will overestimate thestructural anti collapse capability, when the overall structure is studied on the elasticplastic analysis, it is necessary to consider into the joints model, to make theanalysis result more reasonable. |
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