【机 构】
:
DepartmentofCivilEngeering,ChongqingResearchInstituteofBuildingScience
【基金项目】
:
Project (No. 863-2-4) supported by the National Basic Research Program (863) of China ACKN0WLEDGEMENTIn this paper we got a lot of help from Dr. Michael C. Lu, whom we thank very much.