Research On Seismic Behavior Of Raw-soil Structure Buildings In Villages And Small Towns

Raw-soil structure building is an important part of Chinese traditional architecture, it hasthe advantages of obtaining materials locally, low cost, simple construction technology, greenand environmental protection, superior heat preservation and heat insulation performance,biodegradable and renewable, low energy consumption and no pollution in its constructionprocess. So earth dwellings have been widely used in our country vast western rural regions.However, the seismic performance of raw-soil structure buildings is a main difficulty in theirexisting and development today. This paper conduct research on the basis of the seismicperformance of raw-soil structure buildings in China, series of research are done frominvestigation about buildings in villages and small towns, the physical and mechanicalproperties test of the soil, the experimental study on seismic behavior of the bearing earthwalls, which are the main bearing components of the raw-soil structure buildings, thetheoretical calculation methods and the restoring force model of the bearing earth walls, theresearch on construction technology and seismic constructional measures of raw-soil structurehousing. The major works and results include:1. The physical and mechanical properties of the soil used in the raw-soil structurebuildings in villages and small towns are studied. The physical properties of the soil, the valueof the adobe and rammed earth strength and the methods in determining the adobe andrammed earth strength are obtained, which provide basic data for the study on seismicbehavior of raw-soil structure housing in the villages.2. Series of experimental study are done on seismic behavior of the bearing earth walls,which are the main bearing components of the raw-soil structure buildings still used in ourcountry. Pseudo-static tests are conducted for14specimens of the bearing earth walls underrepeated horizontal loading, with their failure process, failure mode analyzed and investigated,together with the hysteretic curve and skeleton curve feature, the horizontal bearing capacityand deformation capacity of the walls, energy dissipation, strength and rigidity degradation,etc. Test results indicated compared with the traditional earth walls that the seismic behaviorof the new design walls are improved in different degree by built-in rope nets constructionmethod, setting the wooden columns and ring beam frame and others constructional measures, construction technology and the strengthening methods.3. Based on results of the experiment, the failure mechanism and the calculation methodsof the bearing walls in the raw-soil structure housing are analyzed and studied. Then, thecalculating formulas of the bearing earth walls for the shear bearing capacity are put forward.4. On the basis of testing data, the dimensionless skeleton curves of the bearing earthwalls in the raw-soil structure buildings under repeated horizontal loading are fitted and thebasic parameters for simplified trilinear models are obtained; Formula of the skeleton curvesare put forth by using the methods of theoretical analysis and regression; Based on hysteresisrules of specimens, the restoring force model of the bearing earth walls is constructed.5. On the basis of cyclic loading test of the bearing earth walls in the raw-soil structurebuildings, the seismic performance of the bearing earth walls can be divided into four levels:performance continuity, performance interruption, life safety and collapse prevention. And thelimit state of the different seismic performance levels and the range of deformation limits ofthe bearing earth walls are given for four different seismic performance levels. And the shearstrength values of the unit width prototype earth walls are given in each performance level.6. The seismic achievements of raw-soil structure housing in the scientific research andengineering experience are summed up, then the seismic constructional measures suggestionsand construction instructions of raw-soil structure housing in the villages are given from thefields of the material selection, the structure system, the foundation, the wall and the roofsystem, which will provide technical support for the construction of raw-soil structurebuildings in the villages and small towns.The above results can provide practical technology for raw-soil structure buildings newconstruction, reinforcement and reconstruction in the villages, which is economically feasibleand scientific and rational, and has been or will be applied in the national standards, industrystandards or local rules.