The Analysis Of Precast Concrete Stairs In Frame Structure On The Seismic Performance

Construction industrialization implementation with prefabricated building promotion,resource saving and environmental friendly,is a practice for sustainable development.Within global warming,awareness of environment and resource crisis,construction industrialization is a low carbon action and measures,essential to consumers,construction industry and all other related industries.Published in year 2016,Limitation and Prohibition on the Use of Backward Technology in Chongqing Construction Industry has prescribed that cast-in-situ stair process shall not be used for urban reinforced concrete share wall structure of more than 80,000 square meters;prefabricated concrete precast technology shall be used instead.Stairs is an important component of the building structure,as well as vital evacuation access during earthquake and other emergencies,but traditional design considers less involvement of stairs in the whole building structure function,neither does it include seismic designs on stair itself.In construction industrialization implementation,precast stair also plays an important role;however,existing studies on seismic function of precast stairs itself and how it affects the frame structure are rare.Therefore,study on precast stairs is of necessity.The dissertation uses finite element analysis software SPA2000 to build analysis models of precast and cast-in-situ concrete stair frame structure;and studies in the response spectrum analysis,the seismic performance of precast concrete stair itself and how it affects the frame structure,comparing to cast-in-situ concrete stair;builds the models,in Pushover Nonlinear Analysis,and studies precast concrete stair’s yield properties under elastic-plastic status of major earthquake.In Nonlinear Dynamic Analysis,three different seismic waves from the code,analyzes and compares the seismic performance of both models under elastic-plastic status of major earthquake.Analysis results show that compared to cast-in-situ concrete stair frame structure,precast concrete stair can reduce the lateral stiffness of frame structure,significantly weaken the frame structure lateral stiffness in parallel tread direction;effectively reduce axial force and shear force of frame structure tread under earthquake,obviously increase bending moment,which indicates the necessity to improve design value of precast stair;can effectively reduce stair beam’s shear force,bending moment,torque,and effectively protect stair load components and the integrity of the staircase.Pushover Analysis shows plastic hinge development is slower in precast concrete stair frame structure than in cast-in-situ concrete stair frame structure;and precast concrete stair frame structure can lighten the damage of destroy to a certain extent.In Nonlinear Dynamic Analysis,under the effects of three different seismic waves,both stair models’ maximum and interfloor shifts is still within the national standards requirements,at a stable state even under earthquake intensity of 7 degrees.