lecture14 - Lecture 14- Bar Lecture 14- Bar Development...

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Unformatted text preview: Lecture 14- Bar Lecture 14- Bar Development Development July 9, 2003 CVEN 444 Lecture Goals Lecture Goals Critical Sections Hook Development Bar Cutoff Critical Sections in Flexural Members Critical Sections in Flexural Members The critical sections for development of reinforcement in flexural members are: At points of maximum stress; At points where tension bars within span are terminated or bent; At the face of the support; At points of inflection at which moment changes sign. 1. 2. 3. 4. Critical Sections in Negative Critical Sections in Negative Moment Reinforcement Moment Reinforcement Three sections are critical for the negative moment reinforcement: Section 1 is at the face of the support, where the negative moment as well as stress are at maximum value. Two development lengths, x 1 and x 2 must be checked. Critical Sections in Negative Critical Sections in Negative Moment Reinforcement Moment Reinforcement Section 2 is the section where part of the negative reinforcement bar can be terminated. To develop full tensile force, the bars should extend a distance x 2 before they can be terminated Once part of the bars are terminated the remaining bars develop maximum stress. Critical Sections in Negative Critical Sections in Negative Moment Reinforcement Moment Reinforcement Section 3 is a point of inflection The bars shall extend a distance x 3 beyond section 3: x 3 must be equal to or greater than the effective depth d, 12d b or 1/16 the span, which ever is greater. At least 1/3 of the total reinforcement provided for negative moment at support shall extend a distance x 3 beyond the point of inflection. Critical Sections in Positive Critical Sections in Positive Moment Reinforcement Moment Reinforcement Section 4 is that of maximum positive moment and maximum stresses. Two development lengths x 1 and x 2 have to be checked. The length x 1 is the development length l d specified by the ACI Code Section 12.11. The length x 2 is equal to or greater than the effective depth d, 12d b . Critical Sections in Positive Critical Sections in Positive Moment Reinforcement Moment Reinforcement Section 5 is where part of the positive reinforcement bars may be terminated. To develop full tensile force, the bars should extend a distance x 2 . The remaining bars will have a maximum stress due to the termination of part of the bars. Critical Sections in Positive Critical Sections in Positive Moment Reinforcement Moment Reinforcement Section 5 At the face of the support section 1, at least 1/4 of the positive moment reinforcement in continuous members shall expend along the same face of the member into the support, according to ACI 12.11.1. For simple members at least 1/3 of the reinforcement shall extend into the support Critical Sections in Positive Critical Sections in Positive Moment Reinforcement...
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This note was uploaded on 10/03/2011 for the course CVEN 444 taught by Professor Staff during the Summer '08 term at Texas A&M.

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lecture14 - Lecture 14- Bar Lecture 14- Bar Development...

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