混凝土强度等级对全珊瑚海水钢筋混凝土梁抗剪性能的影响

Influence of concrete strength grade to the shear behavior of coral aggregate reinforced concrete beam

通过对全珊瑚海水钢筋混凝土梁(coral aggregate reinforced concrete beam, CARCB)和普通钢筋混凝土梁(ordinary aggregate reinforced concrete beam, OARCB)进行斜截面抗剪性能试验,研究了混凝土强度等级对CARCB的裂缝发展、破坏形态、跨中变形及抗剪承载能力的影响,建立了弯矩-跨中挠度、挠度-梁长、荷载-最大裂缝宽度的关系,探讨了CARCB抗剪承载力(Vcs)的计算模型.结果表明:随着混凝土强度等级的提高, CARCB正截面开裂荷载(Vcr)、斜截面Vcr和Vcs均逐渐增大.不同混凝土强度等级的CARCB,其裂缝宽度均随着荷载的增大而增长,加载初期,在梁跨中附近出现正截面弯曲裂缝,裂缝宽度开展非常缓慢,随着荷载的增加,在支座向集中力作用点处出现斜裂缝,斜裂缝宽度迅速增大,最终导致梁破坏.在C60的CARCB中采用有机新涂层钢筋能有效抑制钢筋锈蚀.最后,综合考虑箍筋锈蚀和高强珊瑚混凝土(coral aggregate concrete, CAC)的影响,提出了更加合理的CARCB抗剪承载力计算模型.

The shear behavior of CARCB and OARCB were tested, the concrete strength grades were selected as parameters, the crack development, failure mode, midspan deflection and Vcswere studied, the relationships of bending moment-midspan deflection,deflection-beam length and load-maximum crack width were established, a calculation model for the Vcsof CARCB was suggested.The test results showed that the normal section Vcr, inclined section Vcrand Vcsincreased with the increase of concrete strength grade.The CARCB crack width increased with the increase of load for different concrete strength grades. In the initial loading stage, flexural cracks occurred at the midspan of the beam with slow development. However, as the load increased, inclined cracks were formed from the support to the concentrated force point, which widened rapidly, leading to beam failure. The application of organic new coated steel in the C60 CAC structure was suggested to effectively inhibit steel corrosion. Therefore, comprehensive consideration on the effects of stirrup corrosion and high-strength concrete on Vcsof CARCB, a calculation model for the Vcsof CARCB was proposed.