Effects Of Infilled Wall On RC Frame Structural Collapse And Anti-Collpse Measures

A basic task of structural design is to ensure the safety of buildings, and one of the significant aspects in structural design is to prevent the structure from col-lapse under the loads of accidenttal event or earthquake. Infilled frame structure is a widely used structure type in practical application. As an important part of the structure, the infilled wall is only taken as a load or reduced by its stiffness in the usual analysis and design. But these handling methods cannot well reflect the mechanism of cooperative work between the infilled wall and frame structure's beams or columns and the effect of the inflled wall on the frame structure. Based on the above issues, a 4-story, a 8-story and a 12-story reinforced concrete frame structures are designed according to Chinese codes. The infilled wall effects on frame structure to resist progressive collapse and seismic collapse are studied, and the corresponding anti-collapse measures are proposed. The main contents are as follows.1. ABAQUS software is used to verify progressive collapse test, infilled wall frame test, multi-story and multi-span frame structure test, frame-truss test and multi-story infilled frame test. The reinforced concrete frame structures are modeled with constitutive relation of the materials, element type , contact relation model and determination methods of their parameters which adopted in model verification.2. Based on alternate load path method, with and without infilled wall RC frame are analyzed with nonlinear static analysis method, nonlinear dynamic analysis method and vertical incremental dynamic analysis method. The effect of infilled walls on infilled frame is studied from the following aspects: vertical displacement of collumn failure point, change of the internal forces of structural members, energy of the structure and structural anti-collapse capacity.3. Based on time history analysis method, with and without infilled wall frame are analyzed under frequently occurred earthquake and rare earthquake. The effect of infilled walls on frame is studied by the following indexes: story peak acceleration, story drift, floor displacement and energy of the structure. By the above study it can be found that RC frame structures with weakness story at bottom are liable to collapse under rare earthquake.4. Based on the anti-collapse method of common steel brace, anti-collapse of pure frame structure and seismic collapse of infilled frame structure are studied using different types and different layouts of brace respectively. The results show that rational layout of structural brace can better improve the structural anti-collapse capabilities.