浅谈国际标准中结构可靠度设计新方法

Discussion on a New Method of Structure Reliability Design in International Standard

结构可靠指标在建筑结构设计中具有重要意义,特别是在重大自然灾害发生时显得尤为重要。而目前我国所采用的结构设计方法是以分项系数表达的近似概率极限状态设计法,虽然克服了过去完全依据经验控制结构可靠度的缺陷,但仍难以直接反映可靠指标变化对设计结果的影响,只能根据经验对设计表达式中的分项系数或荷载标准值做适当调整,这与设计方法本身的先进性是不相符的。针对此问题,国际上提出了一种工程结构可靠度设计的新方法,即"设计值法"。其最突出的特点就是直接建立了可靠指标与荷载、抗力设计值之间的关系,能够明确反映可靠指标变化对设计结果的影响。根据目前国内外大量文献资料,介绍了设计值法的基本思想和基础理论,针对我国发展现状和规范校核原则,考虑可靠指标与荷载、抗力设计值的关系,寻求设计值法与我国现行结构设计方法的异同及在我国应用的可行性。

The reliability index of structure has great significance in structure design, especially when big natural disasters occur. The structure design mehtod adopted in China currently is the similarly probabilistic design method of limit state, which is expressed as partial factors. Although it overcomes the ever shortcomings that the structure reliability degree is controlled by experiences completely, it＇s still very difficult to reflect the design result directly that is caused by the changing of reliability index. Designers can only adjust the partial factors or characteristic values of load in design presentation, which conflicts with the advances of the design method. Recently, a new kind of design methods for engineering structure reliability is introduced in intemaional codes, calied ＂design value method＂. Its remarkable advantage is to establish connections between the reliability index and the design values of load and resistance, which is able to solve the problem above. The basic principle and theory of the design value method are introduced according to a host of literatures at home and abroad. The differences between the past design method and the new one are also compared here. Considering the modification principle of domestic codes, the feasibility of the design value method in China could be found out.