长沙理工大学：《结构设计原理》课程教学资源（PPT课件）Chapter 7 Load-Carrying Capacity of Normal Section of Members under Eccentric Loads

JPKIC 结构计原黑 Chapter 7 Load-Carrying Capacity of Normal Section of Members under Eccentric Loads

Chapter 7 Load-Carrying Capacity of Normal Section of Members under Eccentric Loads

JPKIC Focus of this chapter: 结构设计原理 The principle of structure design bias components are the mechanical characteristics of cross sections and two failure modes, Boundaries and determine the size of bias conditions; Familiar with eccentric compression ofthe second-ordereffect and calculation; Eccentric rectangular cross-section bearing capacity of compression members is calculated, Including the formula,the formula of the applicable conditions of reinforcement and non-symmetrical Design and reinforcement of the cross-section symmetrical cross section for review; OI-shaped,T shaped eccentric compression AND CIVIL ENGINEERING Calculation method; OCircularsectioneccentric compression member cross section design and review; OEccentric compression reinforcement of the structure and reasonable layout requirements

Focus of this chapter: ●bias components are the mechanical characteristics of cross sections and two failure modes, ●Boundaries and determine the size of bias conditions; Familiar with eccentric compression of the second-order effect and calculation; Eccentric rectangular cross-section bearing capacity of compression members is calculated, Including the formula, the formula of the applicable conditions of reinforcement and non-symmetrical ●Design and reinforcement of the cross-section symmetrical cross section for review; ●I-shaped, T shaped eccentric compression AND CIVIL ENGINEERING Calculation method; ●Circular section eccentric compression member cross section design and review; ●Eccentric compression reinforcement of the structure and reasonable layout requirements

JPKIC 结构设计原理 Tfeprniipledistnctiredesign §7.1 Overview $7.1.1 The definition Eccentric compression:The role of N when the axial line of the pressure off the axis of compression members. (a) ) Figure 7-1 The role of eccentric compression force location

Eccentric compression: The role of N when the axial line of the pressure off the axis of compression members. Figure 7-1 The role of eccentric compression force location §7.1 Overview §7.1.1 The definition

JPKic 箱构计原黑 Eccentric is the axial pressure by both the role of N and bending moment M,is equivalent to the centroid of the cross-section eccentricity:e.M/N of the eccentric pressure. M=Ne0 Figure 7-2 eccentric compression and bending structures

Eccentric is the axial pressure by both the role of N and bending moment M, is equivalent to the centroid of the cross-section eccentricity: e. = M / N of the eccentric pressure. Figure 7-2 eccentric compression and bending structures

JPKIC 结构设计原理 jhepnhepledstucturedesgn Eccentricity:The role of N point of the pressure from the member section centroid distance eo Bending structures:Axial pressure to bear on the same cross-section and moment components. Eccentric force component Large eccentric Eccentric: compression (flexure and compression) Small eccentric compression Two-way eccentric force component S 7.1.2 Engineering Eccentric compression:The reinforced concrete arch bridge,truss rod bent, rigid frame column,the column pier(Taiwan)Pier (Taiwan)column and so on

§7.1.2 Engineering Eccentric compression: The reinforced concrete arch bridge, truss rod bent, rigid frame column, the column pier (Taiwan) Pier (Taiwan) column and so on. Eccentric: (flexure and compression) Eccentric force component Two-way eccentric force component Large eccentric compression Small eccentric compression Bending structures: Axial pressure to bear on the same cross-section and moment components. Eccentricity: The role of N point of the pressure from the member section centroid distance e0

JIPlKIC 结构设计原理 The principle of structure design 7.1.3 Construction requirements (1)Rectangular cross-section for the most common form of Section height h is greater than 600mm,use more eccentric compression Shaped or box-shaped cross section. Circular section is mainly used for column Pier,Pile Foundation

(1) Rectangular cross-section for the most common form of Section height h is greater than 600mm, use more eccentric compression Shaped or box-shaped cross section. Circular section is mainly used for column Pier, Pile Foundation. §7.1.3 Construction requirements

JPKIC 结构设计原理 jhepnihplestncturedesig (2)Cross-section dimensions:Rectangular cross-section should not be less than the minimum size 300mm,length of the side ratio of 1.5-3, the long side in the direction of bending. (3)Vertical steel Large eccentric compression: A+4=1%~3% A Eccentric Compression: A+A=0.5%~2% A

(2) Cross-section dimensions: Rectangular cross-section should not be less than the minimum size 300mm, length of the side ratio of 1.5-3, the long side in the direction of bending. (3) Vertical steel Large eccentric compression: Eccentric Compression: =1%~3%  + = A As As  =0.5%~2% + = A As As 

JPKIC 结构设计原理 The principle of structure design S 7.2 Flexural Characteristics And Failure Modes S 7.2.1 The failure modes of eccentric compression N M (=Neo) Figure7-4eccentric compression

Figure7-4eccentric compression N e0 N M（=Ne0） §7.2 Flexural Characteristics And Failure Modes §7.2.1 The failure modes of eccentric compression

JPKIC 结构设计原理 Tfepmieipleistrcturdesign 1.Tensile failure-big eccentric compressive damage Produce conditions:(e/h)large relative eccentricity, And the tension reinforcement configuration Debu too much. FAlLURE Some tension,some pressure,tensile reinforcement stress Yield strength is reached first,and then,concrete is pushed Chopped up to yield strength of compression reinforcement Bearing components Set depends upon the strength and tensile reinforcement quantity. Destruction of nature:plastic failure

1. Tensile failure - big eccentric compressive damage  Destruction of nature: plastic failure.  Produce conditions: (e/h)large relative eccentricity, And the tension reinforcement configuration Debu too much. Some tension, some pressure, tensile reinforcement stress Yield strength is reached first, and then, concrete is pushed Chopped up to yield strength of compression reinforcement. Bearing components Set depends upon the strength and tensile reinforcement quantity.  FAILURE： N N

JPKic 结构设计原理 2.Compressive damage-damage to small eccentric compression The principle of structure design ●Produce conditions: (1)A very small eccentricity. (2)(h)smaller eccentricity,or eccentricity larger and more tensile reinforcement. (3)(e/centricity is small,but the pressure from the far side of the vertical bar a small number,while the N side of the bar near the longitudinal forces more time. FAILURE:Generally near the longitudinal force reached the limits of the first side of the concrete compressive strain and crushed the side of the steel reaches the yield strength of longitudinal force from either side of the steel in tension or compression,usually fail to yield strength.Capacity depends on the compression component of concrete compressive strength and steel strength. Destruction of nature:Brittle failure

⚫ Produce conditions: (1) A very small eccentricity. (2) smaller eccentricity, or eccentricity larger and more tensile reinforcement. (3) eccentricity is small, but the pressure from the far side of the vertical bar a small number, while the N side of the bar near the longitudinal forces more time. ⚫ FAILURE:Generally near the longitudinal force reached the limits of the first side of the concrete compressive strain and crushed the side of the steel reaches the yield strength of longitudinal force from either side of the steel in tension or compression, usually fail to yield strength. Capacity depends on the compression component of concrete compressive strength and steel strength. ⚫ Destruction of nature: Brittle failure. ( / ) 0 e h ( / ) 0 e h N N 2. Compressive damage - damage to small eccentric compression