长沙理工大学：《结构设计原理》课程教学资源（PPT课件）Chapter 9 Crack width

JPKIC 结构设计原理 jhepniplestctredesig Chapter 9 Computation of Stress,Crack width and Reflection of RC Flexural Members

Chapter 9 Computation of Stress, Crack width and Reflection of RC Flexural Members

JIPKIC 结构设计原理 The principle of structure design The main content of this chapter Characteristics of use of reinforced concrete beam during the calculation. The concept of transformed section and the geometric characteristics. The stress state of reinforced concrete short-term checking. Flexural members of the cracks and the maximum width of crack. Deformation of flexural members. Durability of concrete structures

 Characteristics of use of reinforced concrete beam during the calculation.  The concept of transformed section and the geometric characteristics.  The stress state of reinforced concrete short-term checking.  Flexural members of the cracks and the maximum width of crack.  Deformation of flexural members.  Durability of concrete structures. The main content of this chapter ：

JPKIC 结构设计原理 Tfepmieipleistrcturdesign §9.1 Overview $9.1.1 The difference between the two limit state Ultimate limit state calculation: Discussion of the force components in a variety of state of the bearing capacity,bearing capacity is to ensure the structural safety of the first condition,which determines the size of components,materials,and structural reinforcement

§9.1 Overview §9.1.1 The difference between the two limit state ⚫ Ultimate limit state calculation: Discussion of the force components in a variety of state of the bearing capacity,bearing capacity is to ensure the structural safety of the first condition, which determines the size of components, materials, and structural reinforcement

JIPlKIC 结构设计原理 The principle of structure design Normal limit state checking: In addition to reinforced concrete strength may be due to reasons such damage orfailure to achieve ultimate limit state,it also may be due to components such as excessive distortion or cracks in the applicability and durability of components,but not reach the structure of the normal requirements.Therefore,for all reinforced concrete structures are required for bearing capacity,while some of the components,but also according to the normal conditions of use for checking limit state to ensure that undernormal use stress,cracks and distortion is less than normal Limit state limits

⚫ Normal limit state checking: In addition to reinforced concrete strength may be due to reasons such damage orfailure to achieve ultimate limit state, it also may be due to components such as excessive distortion or cracks in the applicability and durability of components, but not reach the structure of the normal requirements. Therefore, for all reinforced concrete structures are required for bearing capacity, while some of the components, but also according to the normal conditions of use for checking limit state to ensure that undernormal use stress, cracks and distortion is less than normal Limit state limits

JPKIC 结构设计原理 hepnimeipledtstrnicturedesign $9.1.2 Normal checking the contents of the limit state: Construction phase of the concrete and steel stress check. Deformation in the service phase. ● Maximum crack width in the service phase

§9.1.2 Normal checking the contents of the limit state: ⚫ Construction phase of the concrete and steel stress check. ⚫ Deformation in the service phase. ⚫ Maximum crack width in the service phase

JIPlKIC 箱构设计原黑 $9.1.3 The characteristics of normal use (compared with the ultimate limit state) Calculated according to different:Ultimate limit state is the failure stage(II a)of the state schema for the establishment of the basis of calculation;and use phase generally refers to the first stage II, thebeam with a crack session

§9.1.3 The characteristics of normal use (compared with the ultimate limit state) ⚫ Calculated according to different: Ultimate limit state is the failure stage (Ⅲ a) of the state schema for the establishment of the basis of calculation; and use phase generally refers to the first stage Ⅱ, thebeam with a crack session

JPKIC 结构设计原理 jhepniiplestncturedesgn Different levels of impact:Compared with the ultimate limit state,more than the normal limit state consequences(such as casualties and economic losses)and severity of the danger of relativelysmaller,lighter,and thus may be appropriate to ensure the reliability of its rate ofrelaxation Requirements

⚫ Different levels of impact: Compared with the ultimate limit state, more than the normal limit state consequences(such as casualties and economic losses) and severity of the danger of relativelysmaller, lighter, and thus may be appropriate to ensure the reliability of its rate ofrelaxation Requirements

JIPlKIC 结构设计原理 The principle of structure design o The different contents of calculation >Ultimate limit state:Including cross section design and review. The calculation determines the size of component design, material,quantity and steelreinforcement layout,to ensure that: YoMa≤Muo >Serviceability limitstate Checking under normal use and deformation of crack width is less than thespecification limits

⚫ The different contents of calculation ： ➢ Ultimate limit state:Including cross section design and review. The calculation determines the size of component design, material, quantity and steelreinforcement layout, to ensure that: γ0Md≤Mu。 ➢ Serviceability limit state ：Checking under normal use and deformation of crack width is less than thespecification limits

JPKIC 结构设计原理 Tfeprniipledistnctiredesign Load and resistance values of the different Ultimate limit state Vehicle loads should be included in the impact factor,the role (or load)effect and the resistance of structural components should be considered a partial coefficients usingthe design value;in a variety of roles (or load) effect the case,should the design valueof the effect The most dangerous combination,and the role of the participatingportfolio(or load)effect situation,access to the different effects of combination coefficients

⚫ Load and resistance values ​of the different ➢ Ultimate limit state ：Vehicle loads should be included in the impact factor, the role (or load) effect and the resistance of structural components should be considered a partial coefficients usingthe design value; in a variety of roles (or load) effect the case, should the design valueof the effect The most dangerous combination, and the role of the participatingportfolio (or load) effect situation, access to the different effects of combination coefficients

JIPlKIC 结构设计原理 The principle of structure design Serviceability limit state Auto load impact factor should be neglected,the role (or load)effects should be short-term effects and long-term effects of access to one or several combinations.Short-term effects of combination is a permanent role(structural weight)and variablestandard values of the role of the combination effect of frequent value;long-term effectscompared to the permanent role of the standard combination of value and the role ofquasi- permanent value of a variable combination of effects

➢ Serviceability limit state ：Auto load impact factor should be neglected, the role (or load) effects should be short-term effects and long-term effects of access to one or several combinations. Short-term effects of combination is a permanent role (structural weight) and variablestandard values ​of the role of the combination effect of frequent value; long-term effectscompared to the permanent role of the standard combination of value and the role ofquasi￾permanent value of a variable combination of effects