摘要
为了揭示钢管再生混凝土界面黏结滑移的作用机理,采用服役满50年的混凝土作为再生粗骨料来源,设计25根钢管再生混凝土短柱试件进行推出试验。考虑试件的截面形式、再生粗骨料取代率、混凝土强度等级、长径比及界面埋置长度5个变化参数对其黏结性能的影响,获取两类不同钢管再生混凝土的荷载滑移曲线、黏结应变和黏结力分布规律,推导黏结剪力传递长度公式,并运用相关强度公式对钢管再生混凝土的黏结强度进行对比计算。研究结果表明:加载端和自由端的荷载滑移全过程曲线具有相似性,但自由端的初始滑移发展较慢。钢管纵向应变在加载初期和加载末期分别呈负指数分布和线性分布,实测强度较名义黏结强度大。对比得到圆形试件的黏结性能优于方形试件;圆形试件的黏结强度随骨料取代率的变化具有一定的波动性;方形试件的黏结强度随取代率的增大而略为增大;当混凝土强度较高时,其极限黏结强度会有所提高;钢管再生混凝土的黏结强度随长径比的增加而有所降低。
Abstract： To reveal the interaction mechanism of bond-slip performance at the interface of recycled aggregate concrete （RAC）-filled steel tubes （RACFST）, the concrete with accomplished service of full 50 years was used as a source of recycled coarse aggregate （RCA） , and a total of 25 RACFST short column specimens were designed for the push-out test. Five parameters, including the shape of cross-section, replacement rate of RCA, grade of concrete strength, ratio of length to diameter and interface embedment length, were considered for their influences on the bond-slip behaviors of RACFST. The load-slip curves, distribution laws of bond strain and bond load for these specimens were obtained, and the calculation formula of bond shear transfer length was derived. For the purpose of comparison, practical formulas of bond strength in concrete filled steel tube （CFST） were used to calculate the bond strength of RACFST. The results show that there is a similarity in the whole process curves of load-slip between the loading end and free end, at which the initial slip develops more slowly. The longitudinal strain of steel tube in the early and late loading exhibits a negative exponential distribution and a linear distribution, respectively. The measured results are larger than the values of nominal bond strength. By comparison, the bond performances of circular specimens are superior to those square specimens. With the replacement rate, the bond strength of circular specimens may fluctuate to a certain degree, while the bond strength of square specimens may increase slightly. When the strength grade of concrete is high, its ultimate strength can be improved. Along with the increase of the ratio of length to diameter, the bond strength of RACFST may be reduced to some extent.
出处
《土木工程学报》
EI
CSCD
北大核心
2013年第3期49-58,共10页
China Civil Engineering Journal
基金
国家自然科学基金(50908057)
‘八桂学者’建设工程专项经费
广西自然科学基金(2012GXNSFAA053203)
广西科技攻关项目(桂科攻12118023-3)
广西理工科学实验中心重点项目(LGZX201102)
关键词
钢管再生混凝土
黏结滑移
推出试验
剪力传递长度
黏结强度
recycled aggregate concrete-filled steel tube （RACFST）
bond slip
push-out test
shear transfer length
bond strength
