Study On Seismic Performance Of Rural Rammed Earth Buildings

Rammed earth buildings are made of raw soil material simply processed and consolidated layer by layer by using pestles and other tools. They refer to the buildings constructed by rammed earth wall load-bearing structures and those mixed with rammed earth walls and wooden frames. They are an important part of raw soil buildings.Being a major form of Chinese traditional dwellings, rammed earth houses are the carrier of working people's experience for thousands of years with their own unique cultural heritage. They are the real sense of "green buildings" and "low-carbon buildings". Up to today, they have been existing in large numbers in rural areas because of their ecological advantages of energy saving, environmental protecting and wall material reusing as well as their low cost in particular.Constrained by history and economic development, such buildings are almost not formally designed. They will bring about a lot of problems in structure and construction and be subjected to heavy earthquake damage. In the Wenchuan earthquake, rural houses take up 60 to 70 percent of all the collapsed and damaged, 50% of which are raw soil buildings which are damaged more badly, up to 80% of such bulidings collapsing or becoming dangerous buildings. Thus, for these types of buildings, the seismic analysis are of both urgency and positive practical significance.In order to study the seismic performance of residential rammed earth buildings, and under the support of the national "Eleventh Five-Year" science and technology support projects subject (subject number:2006BAJ04A02-01), this paper is mainly focused on the aspects as following:(1) Through site investigation, we have obtained the related sizes of common structural elements of rammed earth buildings, the traditional construction methods and construction practices, which can help us to get the afforestation technology in rural area and provide a reference for establishing analytic models.(2) Considering the structure properties and material characteristics, finite element method is used in this paper to explore implementation method through finite element software for analysis of such buildings.(3) Structural dynamics theory is used to analyze the finite element model of the rammed earth buildings and the low-level vibration mode and basic cycle parameters of the structure have been obtained which can reflect the dynamic properties of the rammed earth construction.(4) Because the rammed earth buildings have heavy dead weight and weak roof structure, this paper mainly analyses the force and deformation characteristics of rammed earth construction under gravity and earthquake action so as to find out the weak parts of the structure and make corresponding improvements.This paper also compare two types of typical rammed earth housing. These will provide a reference for improving the function of these buildings.(5) Through the seismic response analysis, the displacement response and acceleration response of the structure under frequently or rarely occurring earthquakes are obtained,which can provide reference for the seismic performance evaluation and follow-up study of such buildings.