文档介绍：Chapter 10 Limit State Design Based on Approximate-probability Theory
Limit State
Approximate-probability Limit State Design Method
Practical Design Expression
Introduction to the Limit State Design
1、Action , Direct action, Indirect action
Action
(1)Action:It is the reasons that cause internal forces or deformation in structure.
loads, thermal changes, differential settlement, etc.
(2)Direct Action:concentrated or distributed Loads which are the forces directly applied on the structure.
self weight of structure, pressure due to wind, etc.
(3)Indirect Action:The other reasons except loads which cause internal forces or deformation in structure.
Thermal deformation, differential settlement
2、Action effect、load effect
(1) Action effect:
It is the reaction of a structure to the action. Internal forces, deformation.
(2) Load effect:
It is the reaction of a structure to Loads.
Internal forces, deformation.
3、 Classification of loads
Dead loads
Self-weight, Soil pressure, etc.
Live Loads,
Live load on floors, snow load ,etc.
Permanent loads G
Variable loads Q
Accidental loads
It may not occur during the lifetime of structure. Once occurring, its value is high and durational time is short.
Explosive force, collision force, etc.
(1) Characteristic Values (or Nominal Value) of loads
Permanent loads GK
Variable loads Qk
Determined based on the dimensions of members and the unit weight of materials.
According to the probability and statistic of loads, the maximum probable load under normal condition in the working time of structure.
Illustrate by examples
4. Representative Values of loads
(2) The Quasi-permanent Value of Variable loads
Quasi-permanent Value Qq
The sustained portion of variable load which chronically are applied on the structure.
quasi-permanent value coefficient of variable loads
Combination Value Qc
(3) bination Value of Variable load
combination value coefficient of variable loads
Frequent Val