Chapter 3 Design method
Design method
3.1 Functions which should be satisfied during design Reliability The properties of a structure or part of it will perform its intended function for a specified period of time under required condition
Reliability The properties of a structure or part of it will perform its intended function for a specified period of time under required condition
Intended function Safy(安全性) 正常施工、正常使用条件下，能承受各种可能出现的 外界作用而不发生破坏。偶然事件发生后，保持必要 的整体稳定性 Serviceability(适用性) 正常使用条件下，有良好的使用性能。如吊车梁变形 过大、水池开裂不能蓄水，虽然不引起倒塌，但已丧 失使用功能。 ·Durability(耐久性) The ability of structures to fulfill its intended function during its intended life span. (在预定的时间内完成预定的功能的能力)
l Safety(安全性） 正常施工、正常使用条件下，能承受各种可能出现的 外界作用而不发生破坏。偶然事件发生后，保持必要 的整体稳定性 l Serviceability （适用性） 正常使用条件下，有良好的使用性能。如吊车梁变形 过大、水池开裂不能蓄水，虽然不引起倒塌，但已丧 失使用功能。 l Durability （耐久性） The ability of structures to fulfill its intended function during its intended life span. (在预定的时间内完成预定的功能的能力)
Design purpose To achieve acceptable probabilities(概率) that a structure will not become unfit for its intended use.ie,will not reach a limit state
To achieve acceptable probabilities (概率） that a structure will not become unfit for its intended use. i.e, will not reach a limit state
3.2 Uncertainties in reliability assessment 。Random variables(随机变量) Loads(作用)，material strength,geometry of section, Location of rebars,calculating methods,human errors Design use the concept of probability and apply the methods of statistics
l Random variables (随机变量) Loads(作用), material strength, geometry of section, Location of rebars, calculating methods, human errors Design use the concept of probability and apply the methods of statistics