JPkic 箱构试原黑 Taken along the diagonal crack isolation body on the inclined section of the stress state.It can be seen,the resistance of inclined section are: (1)Shear pressure surface(AA)on the shear stress Dc and Vc; (2)vertical steel tension Ts; (3)friction,aggregate bite force Sa; (4)bolt longitudinal reinforcement of the sales force Vd. By the equilibrium conditions: B AVc 0 Dc x=0 D。=T Y=0 VA=VG ∑M=0 Vaa=T. Can solve? Beams without web reinforcement after diagonal crack appeared isolated body diagram
图4-2 斜裂缝出现后的应力状态 b) C VA D C B Ts a MB B vd c B' Sa MA z Vc A' A Dc A' Beams without web reinforcement after diagonal crack appeared isolated body diagram Taken along the diagonal crack isolation body on the inclined section of the stress state. It can be seen, the resistance of inclined section are: (1)Shear pressure surface (AA) on the shear stress Dc and Vc; (2) vertical steel tension Ts; (3) friction, aggregate bite force Sa; (4) bolt longitudinal reinforcement of the sales force Vd. By the equilibrium conditions: Can solve?
JPKIC 4.1.2 Beams without web reinforcement mechanism 结构设计原理 Thepniepleistrmcturgdesgn of shear:arch model Beams state seen as a set of lever arch:the critical diagonal crack at the top of the basic arch and a group of small arch I,II,III composition,the equivalent of longitudinal reinforcement rods. IIwithstand the internal forces of small arches off bolt,the role of arch occlusal bearing I Arch I bear most of the shear 拱项 Weak parts:I vault arch cross section,the 拱体 cross-section minimum,maximum stress;two- way compressive stress and shear stress together,concrete cutting pressure failure occurs.At this point,there are other parts of I arch bearing potential. Arch II,Π：to pass the shear is very small,.not fully functional. 拉杆
4.1.2 Beams without web reinforcement mechanism of shear: arch model Beams state seen as a set of lever arch: the critical diagonal crack at the top of the basic arch and a group of small arch Ⅰ, Ⅱ, Ⅲ composition, the equivalent of longitudinal reinforcement rods. Ⅱ withstand the internal forces of small arches off bolt, the role of arch occlusal bearing Ⅰ Arch Ⅰ bear most of the shear Weak parts: Ⅰ vault arch cross section, the cross-section minimum, maximum stress; twoway compressive stress and shear stress together, concrete cutting pressure failure occurs. At this point, there are other parts of Ⅰ arch bearing potential. Arch Ⅱ, Ⅲ: to pass the shear is very small, not fully functional. Ⅲ
JPkic 结构盘注原黑 4.1.2 Beams without Web Reinforcement oblique section failure modes: 1.the shear span ratio of the definition:shear span ratio m is a dimensionless number,use the m= Mto indicate,where Mand Vrespectively,a vertical shear V zone cross-section bending moment and shear force,ho for the cross-section Effective height. m cross section of M and V reflect the relative size of the combined effect of the shear-bending 2.the shear span ratio Category: a Generalized shear span ratio: Vho 0 ●Narrow span ratio:
4.1.2 Beams without Web Reinforcement oblique section failure modes: 1. the shear span ratio of the definition: shear span ratio m is a dimensionless number, use the to indicate, where M and V respectively, a vertical shear zone cross-section bending moment and shear force, h0 for the cross-section Effective height. m cross section of M and V reflect the relative size of the combined effect of the shear-bending 2. the shear span ratio Category: Vh0 M m = Vh0 M m = ⚫Narrow span ratio: 0 h a m = a ⚫Generalized shear span ratio:
JPKIC 结构设计原理 Teprimepledtstmtcturgdesign 3.the failure mode:Depending on the size of m a)斜拉破坏 b)剪压破坏 c)斜压破坏
图4-2-1 斜截面破坏形态 a) 斜拉破坏 P b) 剪压破坏 c） 斜压破坏 P P 3. the failure mode: Depending on the size of m
JPKIc 箱构其原黑 (1)cable-stayed damage(m>3) ●Produce conditions: a)斜拉破坏 Generally occurs in relatively large shear span(m>3)of the beams without web reinforcement ●Faiure: When the inclined cracks appeared,and soon form a major diagonal crack(critical inclined cracks:a rapid development,leading to shear failure cracks),and quickly extended to the loading point,diagonal pulled off the beam into two parts.Failure surface than the neat,no crush marks,while the longitudinal reinforcement level of tear production is often accompanied by cracks.The damage is the cable-stayed damage
(1) cable-stayed damage (m> 3) Generally occurs in relatively large shear span (m> 3) of the beams without web reinforcement ⚫Produce conditions: a) 斜拉破坏 F ⚫Faiure: When the inclined cracks appeared, and soon form a major diagonal crack (critical inclined cracks: a rapid development, leading to shear failure cracks), and quickly extended to the loading point, diagonal pulled off the beam into two parts . Failure surface than the neat, no crush marks, while the longitudinal reinforcement level of tear production is often accompanied by cracks. The damage is the cable-stayed damage