flexural behavior of rc members
DESCRIPTION
rccTRANSCRIPT
CE-308REINFORCED CONCRETE DESIGN
SPRING 2013
ENGR. YASIR IRFAN BADRASHIASSISTANT PROFESSOR
DEPARTMENT OF CIVIL ENGINEERING, UNIVERSITY OF ENGINEERING & TECHNOLOGY, CAMPUS-III,
BANNU.
FLEXURAL BEHAVIOR OF RC MEMBERS
STAGE 1- UNCRACKED SECTION (ELASTIC RANGE)
FLEXURAL BEHAVIOR OF RC MEMBERS
STAGE 1- UNCRACKED SECTION (ELASTIC RANGE)
FLEXURAL BEHAVIOR OF RC MEMBERS
STAGE 2- CRACKED SECTION (ELASTIC RANGE)
FLEXURAL BEHAVIOR OF RC MEMBERSSTAGE 3- CRACKED SECTION (INELASTIC RANGE)
FLEXURAL BEHAVIOR OF RC MEMBERSSTAGE 3- CRACKED SECTION (INELASTIC RANGE)
FLEXURAL BEHAVIOR OF RC MEMBERSACI 318-02 PROVISIONS FOR DUCTILITY
10.3.3 — Sections are compression-controlled if the net tensile strain in the extreme tension steel, εt, is equal to or less than the compression-controlled strain limit when the concrete in compression reaches its assumed strain limit of 0.003. The compression-controlled strain limit is the net tensile strain in the reinforcement at balanced strain conditions. For Grade 60 reinforcement, and for all pre-stressed reinforcement, it shall be permitted to set the compression-controlled strain limit equal to 0.002.
FLEXURAL BEHAVIOR OF RC MEMBERSACI 318-02 PROVISIONS FOR DUCTILITY
10.3.4 — Sections are tension-controlled if the net tensile strain in the extreme tension steel, εt, is equal to or greater than 0.005 when the concrete in compression reaches its assumed strain limit of 0.003. Sections with εt between the compression-controlled strain limit and 0.005 constitute a transition region between compression-controlled and tension-controlled sections.
FLEXURAL BEHAVIOR OF RC MEMBERSACI 318-02 PROVISIONS FOR DUCTILITY
10.3.5 — For nonprestressed flexural members and nonprestressed members with factored axial compressive load less than 0.10fc′Ag, εt at nominal strength shall not be less than 0.004.
Visit to code
Comment: Generally beams fall in this category. However this statement is general and hence columns with axial load less than 0.10 fc Ag also fall in this category . For such ′members, it is convenient to take φ = 0.9 and εt = 0.005
FLEXURAL BEHAVIOR OF RC MEMBERSBEHAVIOR OF SINGLY REINFORCED BEAMS
10.2.7.3 — For fc between 2500 and 4000 psi, β′ 1 shall be taken as 0.85. For fc above ′4000 psi, β1 shall be reduced linearly at a rate of 0.05 for each 1000 psi of strength in excess of 4000 psi, but β1 shall not be taken less than 0.65
Comment on β1
FLEXURAL BEHAVIOR OF RC MEMBERSBEHAVIOR OF SINGLY REINFORCED BEAMS
According to ACI 10.5.1, at every section of a flexural member where tensile reinforcement is required by analysis, the area As provided shall not be less than that given by ρmin.bw.d where, ρmin is equal to 3√ (fc )/fy and not less than 200/fy.′
Minimum Reinforcement