Shaking Table Test And Finite Element Analysis For Rammed Earth Wall Buildings Reinforced With High Ductility Concrete

With a long history,earthen has a long history and it is convenient for construction,help for energy saving and environmental protection and has many advantages such as low cost.In China,earthen buildings are widely distributed in less developed rural areas such as the southwest,northwest of China.There are no detail of seismic design in most of the existing earthen buildings in rural areas.Different degrees of damage and even collapse damage can easily be caused due to earthquake effects.High Ductile Concrete(HDC),a fiber-cement matrix composite material with high strength,high ductility,and high toughness,has gradually been widely adopted in the field of seismic strengthening construction materials for housing buildings in recent years.Based on the field investigation in rural areas of Daliangshan,Sichuan,in this paper,for mono-layer houses with rammed earth wall without seismic structural measures,the masonry strengthening with mortar splint of single-sided steel wire mesh with additional high ductility concrete strips was adopted.Pseudo-earth-quake shaking table tests were conducted to analyze the feasibility and validity of this reinforcement scheme,with a view to providing technical references for the seismic reinforcement of the renovation of dangerous houses with rammed earth walls in rural areas of China.The main content of this article is as follows:(1)Performance test of mechanics of materials was performed on rammed soil samples and High Ductile Concrete.Taking the mono-layer rural rammed earth house in Daliangshan as the prototype,a 1:2 scale test model of rammed earth walled house with wooden roof frame was designed.Based on the theory of the lacking artificial mass,the similarity ratio of the test model was derived.(2)The building test model was made by the process of rammed earth wall building in Daliangshan area.The single-sided steel wire mesh with high ductility concrete strip was adopted.The reinforcement range was 700mm from the roof down and 500mm horizontally extending from the four corners of the house.Within this range,15mm thick high ductility concrete was pressed and plastered.(3)EI-Centro,Qian’an wave and Wolong wave were used in the pseudo-earth-quake shaking table test.The test results showed that small cracks appeared in the test model wall when the seismic action was set at 8 degrees.In the rarely occurred earthquake of 8th degree and 9th degree,the original cracks of rammed earth walls appeared more serious,and the single-sided steel wire mesh high ductility concrete strip reinforcement method can significantly improve the horizontal bearing capacity of rammed earth wall bearing buildings.Under the effect of a rare earthquake of 9 degree,the overall performance of the test model was good and the house was basically undamaged.(4)The data from pseudo-earth-quake shaking table test showed that the natural frequency of the test model of rammed earth wall houses reinforced with single-sided steel wire mesh high ductility concrete strips decays continuously with the increase of the peak seismic wave acceleration,and the decay is small.With the increase of peak acceleration of seismic wave,the structural stiffness decreased at a slower rate.The seismic performance of the test model was good..The method in this paper could effectively improve the lateral stiffness of the structure,and the overall seismic performance of the structure was improved.(5)Finite element analysis models of rammed earth wall buildings and rammed earth wall buildings reinforced with high ductility concrete were established with Sap2000.Static,modal and time history of seismic response of the structure were conducted,and the finite element analysis results showed that the lateral stiffness and overall performance of the structure could be effectively improved by using high ductility concrete reinforcement technique.That is consistent with the test conclusion.There are many advantages of using reinforcing mesh with additional high ductility concrete strips for seismic strengthening,such as low cost,simple and fast construction and good seismic performance.Therefore,this method can effectively solve the problem of insufficient seismic structural measures for rural rammed earth wall building houses.