基于不同目标使用期的既有结构构件可靠指标研究

在进行既有结构的安全性分析和可靠性评定时,对于不同的目标使用期仍直接采用现行规范中的目标可靠指标数值,显然缺乏合理性。基于此,本文选取了14种具有代表性的结构构件,基于恒载+办公楼楼面活荷载、恒载+住宅楼面活荷载、恒载+风荷载3种简单荷载组合,考虑不同可变荷载与永久荷载的比值,根据不同目标使用期内荷载与抗力的统计特性,对可靠指标的数值进行了校准并给出相应的建议值。结果为:目标使用期小于30年时,目标可靠指标?取2.7;目标使用期为30年时,?取3.0;目标使用期大于30年时,?取3.2,这更符合工程实际鉴定时的判断结果。

Study of target reliability index for existing structural elements with different periods of usage

In the safety analysis and reliability assessment for existed structural elements,scholars indiscriminately adopt the unified target reliability index values in the current specifications even for different periods of usage.Obviously,this lacks rationality because it does not reflect the serviced life and different target periods of usage for the existed structural components.Based on this fact,according to the characteristics of structural resistances and loads for existed building structures,the target reliability index with different target periods of usage are deduced by optimal analysis of 14 types of typical structural members taking into account of the different ratios of live load effect to dead load effect and three simple load combinations(dead load floor live load of office,dead load+floor live load of resident,dead load+snow load).Research results are as follows:the target reliable indexβis 2.7 with the target periods of usage is less than 30 years;the target reliable indexβis 3.0 with the target periods of usage is 30 years;the target reliable indexβis 3.2 with the target periods of usage is more than 30 years.This is consistent with the engineering judgment,which can be applied in the safety analysis and reliability assessment for existed structural elements.