The Analysis Of Staircase Effect On Seismic Performance Of Frame-shear Wall Structure

Masonry building with frame-shear wall structure is mainly used for street shops at the bottom of the upper housing project, a large number of small and medium-sized cities in our country, some there, especially used in the frontage of more prosperous location. During the Wenchuan earthquake, many Masonry building with frame-shear wall structures destroyed, the seismic performance need to be researched.Masonry building with frame-shear wall structure on first two stories is a compound structure composed of frame shear wall structure and masonry structure, "upper’s weight is heavier than bottom, and upper’s stiffness is stronger than bottom" is one of the characters of this structure system. The stairs as earthquake and fire emergency escape routes, the impact on the main structure stiffness cannot be ignored.As the branch of Shanxi Province natural science foundation research project which name is "the stairs in the simulation analysis of structural global analysis under the action of earthquake" in 2010, this article summarizes the existing various analysis methods, with Masonry building with frame-shear wall structure on first two stories, and four-floor brick masonry structure at the upper part as the research object. Using finite element analysis software ETABS program, to establish finite element model without stairs (model 1) and decorate stair place in different structures of the finite element model (model 2～6), use response spectrum method and time history method to analysis the seismic performance of each model. Come to the following conclusions:1) The existence of the stairs to the bottom of the frame - shear wall structure make the overall stiffness increased by about 40%.2) The existence of stair makes the frame - shear wall structure at the bottom of the natural vibration period of the shortened about 40%, the biggest overturning moment increased about 30%, and for the torsion modal participation factor, lateral stiffness, translational and torsional effect has a significant effect. So it is necessary to take the stairs as an independent unit to participate in the aseismic calculation and analysis in the structure design.3) For stair platform for the main girder, beam and bearing ladder beam, recommend to add high and strengthening the reinforcement of sorghum. When earthquake comes, ladder column top and bottom end node will appear serious damage, it is recommended that in the later when the stair design should guarantee the ladder column reinforcement, and thus powerful guarantee stair components have enough aseismic ability.4) When stairs from location 1 to location 5 change, Y to the vertex maximum displacement under earthquake, the displacement between layers and the interlayer displacement Angle increases gradually, illustrate the stairs stiffness has a great influence on the structural framework at the bottom of the torsion deformation. So when decorate stair, we must try to avoid a single staircase arrangement in the corner or end, symmetrical layout should follow the structure of the Central Line.