RELIABILITY-BASED ESTIMATES OF DYNAMIC LOAD ALLOWANCE FOR CAPACITY RATING OF PRESTRESSED CONCRETE GIRDER BRIDGES UNDER DIFFERENT ROAD SURFACE CONDITIONS

摘要：

　　The current highway bridge design in the United States follows the AASHTO Load and Resistance Factor Design (LRFD) specifications,which employs a dynamic load allowance,IM,of 0.33 for the dynamic effect of truck/tandem loading.Previous studies have shown,through both field tests and numerical simulations,that the IM value of 0.33 may underestimate the vehicle dynamic effect under poor road surface conditions (RSCs).In this paper,the IM is explicitly modeled as a random variable with different statistical properties for different RSCs.The reliability indices of a selected group of prestressed concrete girder bridges,designed following the AASHTO LRFD code,are then calculated.It is found that while the calculated bridge reliability indices are usually above the target reliability index value of 3.5 under above-average RSCs,they can be significantly below the target value of 3.5 when the RSCs are below average.By selecting a group of IM values for each RSC and calculating the reliability indices of the selected bridges with respect to the selected IM values,an appropriate IM value is suggested for each RSC to achieve a consistent target reliability index.The results presented in this paper are particularly valuable for rating of existing prestressed concrete girder bridges,for which the actual RSCs can be directly evaluated.The RSCs need to be properly taken into account in order to accurately estimate the actual safety of the considered bridge.

关键词： Load and resistance factor design (LRFD) dynamic load allowance (IM) road surface condition (RSC) reliability index

作者: Lu Deng C.S.Cai Michele Barbato

作者单位: College of Civil Engineering, Hunan University, Changsha 410082, P.R.China Dept of Civil and Environmental Engineering, Louisiana State University, Baton Rouge, Louisiana, LA

会议类型: 国际会议

会议名称: The Twelfth International Symposium on Structural Engineering (第十二届结构工程国际研讨会)

会议地点: 武汉

会议语种:英文

页码: 1455-1463

在线出版日期: 2012-11-17（万方平台首次上网日期，不代表论文的发表时间）