第4章 受弯构件的斜截面承载力（1-英英）.pptVIP

2. concrete strength Any type of shear failures is due to that the concrete attains its compressive or tensile strength. The strength of concrete directly affects the shear strength of members. The shear strength of members increases with the concrete strength and the relation is nearly linear. Shear strength against cubic strength of concrete 4.3 Factors Affecting the Strength of Diagonal Section （混凝土强度） 3. Stirrup ratio and the strength of stirrup The stirrup ratio is given by where ——leg number of stirrup; ——area of one leg of stirrup; ——spacing of stirrup. With the increase of the ratio and yielding strength , the shear strength Vu tends to increase, and the relation is linear. b Asv1 s Asv= 2Asv1 （配箍率和箍筋强度） 4. Longitudinal steel ratio The longitudinal bar can supply dowel action force, that it can resist some of shear forces in the cross section. The longitudinal bar can restrict the extending of diagonal cracks, and then enlarge the compression zone. With the increase of , the shear strength increases slightly. dowel action force 4.3 Factors Affecting the Strength of Diagonal Section （纵筋配筋率） 5. Loading way directly loading and indirectly loading Indirectly loading leads to decrease of the shear strength. In lab loading test, the beam is usually loaded directly on its top face, that is called “directly loading ” In practical project, such as cast-in-situ ribbed floor, the load of secondary beam is acted on the middle or bottom zone of main beam, that is called “indirectly loading ” compression zone main beam secondary beam 4.3 Factors Affecting the Strength of Diagonal Section （加载方式） Indirectly loading leads to decrease of the shear strength. 6. Section form For T-section beam or I-section beam, the existence of flang