The Study About Fortifications Lines For Column-beam-wall-stairs Structure System Of Masonry Buildings With RC Framed Lower Floor

The so called’bottom frame wall masonry buildings’we talked about means it has reinforced frame shear-wall structure at bottom with masonry structure at upper space, which is the masonry buildings with RC framed lower floor described in the code seismic design of building. This structure has a characteristic of flexible downside and rigid upside, especially the bottom is soft. If taking stairs’the oblique supporting role into consideration, it will increase the lateral stiffness of the structure, impact on the internal force and deformation of the structure under earthquake. In The Wenchuan Earthquake, this structures’ damage not only shows at the tilt and collapse of the shear-wall at bottom,but also the escaping stairs’ serious earthquake damage, the stairs board pulled off,ladder beam broken at both ends, the staircase column and the underlying frame column structure severely damaged. In order to realize the seismic fortification targets, how to set the reasonable seismic fortifications for column-beam-wall-stairs structure system of masonry buildings with RC framed lower floor, it is worth studying.Based on the meaning and control criterion of the multi-seismic fortification lines, this paper uses the finite element software Sap2000v15and some conception analysis, uses elastic-plastic Pushover method to analysis the masonry building with frame-structure at bottom model (M1), masonry building with frame-shear wall structure at bottom model (M2), brick masonry building with frame-shear wall and staircase structure model (M3), put through the multiple fortification analysis of the three structural models,talk about whether the multi-seismic fortification lines of each structure is reasonable or not, study the yield mechanism of the underlying frame shear wall stairs system model, the order and appearance of the plastic hinge, especially for the staircase destruction,Make sure if the staircase could be the first seismic fortification line of the structure or not, put a overall evaluation of seismic performance.The staircase’ affection can not be ignored. With Stairs take a role in transferring the horizontal earthquake analysis; the fortifications for column-beam-wall-stairs structure system of masonry buildings with RC framed lower floor change a lot. Staircase parts share a lot of the seismic force, and staircase structure don’t have a reasonable yield mechanism and brittle break easily, it is first destroyed and becomes the weak line of the system. The stairs can not be the "safety island" of the structure. The whole structure’s yield mechanism does not break at the proper position of the frame-wall-column-beam as expected.Through analyzing the structural damage and stair’s destruction.This paper puts through some advises. The use of semi-slip-supported stairs is simple and effective. Through adjusting the structure’s constraints, we can make stairs elements won’t participate in transferring down horizontal earthquake actions of building. It may be possible for stairs to become ’safety island’.