Chapter 5 Structure Loads and Responses 5.1.Dead Loads 5.2.Live Loads,Snow and Wind Loads 5.3.Earthquake Loads 5.4.Internal and External Movement 5.5.Response of structures and codes
Chapter 5 Structure Loads and Responses 5.1. Dead Loads 5.2. Live Loads, Snow and Wind Loads 5.3. Earthquake Loads 5.4. Internal and External Movement 5.5. Response of structures and codes
5.5.Response of structures and codes The response of the structure to the loadings Under the dead load the building will be stressed and deflected little. When live load is added,deflection and higher stresses are produced not seriously. -The horizontal effect of wind or earthquake can be quite serious in contrast to the dead and live load situations. -The reserve load capacity supplies the additional 'margin of safety'to take care of catastrophic forces,also keep the behavior of the structure within tolerable limits of movement
5.5. Response of structures and codes The response of the structure to the loadings - Under the dead load the building will be stressed and deflected little. - When live load is added,deflection and higher stresses are produced not seriously. -The horizontal effect of wind or earthquake can be quite serious in contrast to the dead and live load situations. -The reserve load capacity supplies the additional ‘margin of safety’ to take care of catastrophic forces, also keep the behavior of the structure within tolerable limits of movement
Fig.5-6 Life history of a structure ELASTIC BEHAVIOR PLASTIC BEHAVIOR ULTIMATE LOAD RESERVE LOAD CAPACITY WIND OR E.Q.LOAD LIVE LOAD DEAD LDAD DEFLECTION ONLY PARTIAL OR ZER LIVE LOAD CONSIDERED TOGETHER WITH WIND OR E
Fig.5-6 Life history of a structure
Fig.5-6 Life history of a prestressed structure 学 ArEn☑ PRESTRESSED LOAD CURVE NON-PRESTRESSED CURVE WIND 0RE.Q.lOAD￥ LIVE LOAD DEAD LOAD (LITTLE OR NO DEFLECTION) DEFLECTION *ONLY PARTIAL OR ZERO LIVE LOAD CONSIDERED TOGETHER WITH WIND OR
Fig.5-6 Life history of a prestressed structure
Codes Modern building codes have changes the "allowable stress"approach to a more reasonable "ultimate strength"design method. A building designer should use building codes only as a reference and as a guide,but not bible.Some code requirements are excessively conservative,others are not sufficient(especially for unusual designs)
Codes Modern building codes have changes the “allowable stress” approach to a more reasonable “ultimate strength” design method. A building designer should use building codes only as a reference and as a guide, but not bible. Some code requirements are excessively conservative, others are not sufficient (especially for unusual designs)
How safe is safe enough? 我国的结构设计安全储备 是否应该大幅度提高？ 墨 盒 ]储 国内生产总值变化曲线 安全储备变化曲线 ■ 50 60 70 80 g0 year
How safe is safe enough? 我国的结构设计安全储备 是否应该大幅度提高？ 50 60 70 80 90 year 国 内 生 产 总 值 安 全 储 备 安 全 储 备 变 化 曲 线 国 内 生 产 总 值 变 化 曲 线
Chapter 6 Overall Design of Horizontal Subsystem 6.1.Overall Structural Behavior of HS 6.2.Flat-Slab Subsystem 6.3.Slab-Beam Subsystem 6.4.Joist-Girder Subsystem 6.5.Waffle Subsystem 6.6.Space Truss Subsystem
Chapter 6 Overall Design of Horizontal Subsystem 6.1. Overall Structural Behavior of HS 6.2. Flat-Slab Subsystem 6.3. Slab-Beam Subsystem 6.4. Joist-Girder Subsystem 6.5. Waffle Subsystem 6.6. Space Truss Subsystem
The relationship of HS and VS: Closer column (expensive VS) =reducing the thickness of the slab/beam (economic HS) But it loses space openness and flexibility of use
The relationship of HS and VS: Closer column (expensive VS) =reducing the thickness of the slab/beam (economic HS) But it loses space openness and flexibility of use
6.1.Overall Structural Behavior of Horizontal Subsystems Horizontal subsystems, which are formed by slab,beam grid and truss,act vertically to carry floor and roof loads in bending.It also pick up loads from the vertical subsystems and resist horizontal forces
6.1. Overall Structural Behavior of Horizontal Subsystems Horizontal subsystems, which are formed by slab, beam grid and truss, act vertically to carry floor and roof loads in bending. It also pick up loads from the vertical subsystems and resist horizontal forces
Key of the horizontal subsystem design -Overall bending behavior (bending design) -Shearing forces near the supports (punching shear check)
Key of the horizontal subsystem design -Overall bending behavior (bending design) -Shearing forces near the supports (punching shear check)