Research On The Collapse Mechanism Of The Seismic Design Of URM Teaching Building

In the wenchuan earthquake,a lot of unreinforced masonry structure buildings collapsed,which caused great damage to life and property.Both the unreinforced masonry buildings in earthquake zones are still abound,which need reinforcement and reconstruction It has very important significance to study the mechanism of this kind of teaching building collapsed.Masonry structure of the building of vertical and horizontal wall hybrid bewring,a part of the floor load spread to the masonry cross wall through the floor,the other part of the floor load spread to the masonry wall through the floor.Under the seismic action,cross wall bear the horizontal shear force and vertical load,the "framework" of the vertical wall and deep beam main bear the vertical load on the beam and a tiny part of the horizontal shear,and the system of building is similar to "frame-shear" structure.Before the cross wall cracking,floor displacement is small,this structure has good ability to work together.Once the cross wall cracking,the floor displacement increases greatly,which increases the vertical wall displacement between layers,and the longitudinal wall under eccentric compression load of eccentricity is greatly increased.Vertical bearing capacity of longitudinal wall is reduced,the destruction of the longitudinal wall leads to the overall collapse of the building.To study the collapse mechanism of masonry structure buildings,this paper made researches as follow:Firstly,study on out-of-plane mechanical performance of unreinforced masonry wall,which analysis the change rule of non-crack and crack unreinforced masonry wall with the wall horizontal displacement increases the wall cross section of stress distribution under the vertical load,and derive crack load and crack displacement of non-crack and crack wall.Considering the vertical load eccentricity and depth-thickness ratio,the wall of cracking to collapse of each phase of the out-of-plane of P-△ curve and the wall collapsed limit displacement.Reference model of Ctough,we put forward half the degradation of linear restoring force model of out-of-plane effect of iion-crack and crack unreinforced masonry wall.Secondly,we have collected test data of domestic plane masonry wall under the action of horizontal loading,analyzed the destruction of the wall characteristics,and put forward the ideal damage model of in-plane loads.Combined with the experiment data,We have regressed the skeleton curves of non-crack and crack unreinforced masonry wall.Reference model of Clough,we put forward half the degradation of linear restoring fcrce model of in-plane effect of non-crack and crack unreinforced masonry wall.Futheremore,we have analyzed three models of non-crack "shear wall" and non-crack " framework ",crack "shear wall" and non-crack " framework r,,and crack "shear wall1’ and crack M firamework ",the collapse of masonry buildings under the action of static bads 5 to get the monotonous nappe of P-△curve of the building structure.Finally,using the skeleton curve and the restoring force model of masonry under in-plane loads and out-of-plane loads,we have studied the performance of masonry structure buildings under tow reversed cyclic load.We got the hysteretic curve and the collapse of masonry buildings of three models.Research shows that the collapsed longitudinal wall led to the collapse of structure.