Experimental Study On Seismic Performance Of Prestressed Reinforced Masonry Buildings Full-scale Model

In recent years, several large-scale earthquakes have occurred in our country and caused serious damages to masonry structures which the seismic performance were weak. Therefore, it is of great significance to reinforce the seismic performance of old masonry buildings.This paper is a part of the major project of Beijing Science and Technology Plan named "Development of the new post-tensioned reset damping technology and retrofit demonstration of the existing masonry structure buildings seismic reinforcement (D131100003713003)". Pseudo-dynamic test under eight load conditions and pseudo-static test in the X and Y axis direction were studied on a prestress reinforced two layers full-scale masonry building model (200m2), and numerical models before and after reinforce are established by MARC finite element analysis software. By study and analysis the damage form and mechanical performance of the structural model, conclusions are drawn as follows:1) The less than eight degree fortification intensity masonry structure has small displacement reaction under nine degree earthquake which the peak acceleration is620gal, and the structure is basically in elastic stage which means an excellent seismic performance.2) On behalf of a good energy dissipation and deformation capacity, the hysteresis loops of the reinforced two layers full-scale masonry building model are full and the descending segments of skeleton curves are flat.3) After reinforce of the two layers full-scale masonry building model, the ratio of structural shear resistance force and total gravity load in both directions are respectively1.24and1.41, and the ratio of unreinforced structure calculated by standardized formula are1.92and1.69. They illustrate that the structure seismic bearing capacity is significantly increased after strengthen.4) Prestress has significant resetting effect to structure which effectively played a role of "second defense" and contribute to achieve the fortified target that "no collapsing under strong earthquake".5) Numerical simulation of the two layers full-scale model which is strengthened by external prestress is done. The result shows that show that the material constitutive model, modeling method and analysis method which have been taken can be used for the numerical simulation and mechanical properties prediction of prestress reinforced masonry structures under complex stress state.Based on studies upon, an demonstration application of external prestress seismic reinforcement on a multistory masonry concrete building has been made and has achieve good results. Firstly, the equipment required is simple, the construction period is short and the cost is low. Secondly, damages to the original structure are less. Last but not least, it is a new type of green seismic reinforcement technology for the reasons that the noise in reinforcement process is small, the environmental pollution and energy consumption are low and the waste of material is less.