Local buckling 局部屈曲 Distosional lateral buckling 组合梁侧扭失稳
Distosional lateral buckling 组合梁侧扭失稳 Local buckling 局部屈曲
Steel reinforcement ·Internal moments in continuous composite beams can be determined by elastic analysis or, -Structural steel subject to certain section conditions,by rigid-plastic analysis 结构分析方法：弹性分析， 塑性极限分析 Negative moment Whether plastic analysis is (a)Both spans loaded appropriate depends on the susceptibility of the beam to local buckling: 0 塑性极限分析适用条件 Negative moment
• Internal moments in continuous composite beams can be determined by elastic analysis or, subject to certain conditions, by rigid-plastic analysis. • 结构分析方法：弹性分析， 塑性极限分析 • Whether plastic analysis is appropriate depends on the susceptibility of the beam to local buckling： • 塑性极限分析适用条件
Tension in slab Applied moment reinforcement Shear in connector (opposite to sagging) Tension or compression in bolts internal Compression in moments in Stiffener bottom flange beam column Vertical shear connection in bolts Forces on the beam column connection in a continuous composite beam However there is also the transfer of longitudinal shear between the concrete and steel to consider and the fact that the bottom part of the steel section is in compression and therefore both flange and web are prone to buckling
internal moments in beam column connection
Point of contraflexure Bending moment diagram Support column Side view Section A-A Displacement V along beam Plan view of bottom flange showing buckle wavelength Maximum buckle length in continuous beam
6.2 Cross Section Classification In a continuous beam,the critical cross-sections must be capable of developing/sustaining their plastic resistance moment,under increasing load, sufficient regions have fully-yield for a mechanism of plastic hinges to be present.(plastic design) The mechanism arises as a result of redistribution of moment.To ensure that the resulting strains can be accommodated without a reduction in resistance below the plastic moment,limitations must be placed on the slenderness of the elements of the cross-section which are in compression
6.2 Cross Section Classification • In a continuous beam, the critical cross-sections must be capable of developing/sustaining their plastic resistance moment, under increasing load, sufficient regions have fully-yield for a mechanism of plastic hinges to be present. (plastic design) • The mechanism arises as a result of redistribution of moment. To ensure that the resulting strains can be accommodated without a reduction in resistance below the plastic moment, limitations must be placed on the slenderness of the elements of the cross-section which are in compression