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为了研究PEC柱(弱轴)-型钢梁顶底角钢连接节点的滞回性能,分别以节点盖板厚度、角钢厚度、螺栓距离(与盖板相连角钢短肢上螺栓中心到角钢肢背的垂直距离)和节点加劲肋为参数,设计了6组节点并对其进行低周往复水平荷载试验。重点研究了4个参数对节点的滞回性能、节点刚度、延性和承载力的影响。试验和分析结果表明,角钢厚度由14 mm增至20 mm,节点极限抗弯强度提高30%,延性提高6.8%,初始刚度提高1.21倍;螺栓距离由80 mm减至70 mm,节点的抗弯能力提高14.8%,初始刚度提高13%,延性降低4.8%。各节点的滞回曲线均呈弓形,延性系数均大于5,承载力退化稳定。角钢厚度增加和螺栓距离减小能明显提高节点的承载力和初始刚度,增加盖板厚度与增设加劲肋可提高节点的初始刚度,对节点的承载力影响不大。建议在设计此类节点时,适当加大角钢厚度,合理减小螺栓距离。

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Bond behavior between recycled concrete and s:eel bar after freeze-thaw damage was analyzed by nine groups of beam-type tests. Numbers of freeze-thaw cycles：, concrete types, strength grade of recycled concrete, anchorage length and bar diameter were selected as the parameters in this experiment. It is shown that all specimens suffer the pulled-out failure. In the same times of freeze-thaw，strength of recycled concrete and anchorage length have a great influence on bond behavior between recycled concrete and steel bar. For specimens with slotted reinforcement， the bond strength is reduced by 8. 5% after 50 times of freeze-thaw cycles and it is reduced by 28. 3% after 150 times of freeze-thaw cycles. The theoretical fitted formula of bond strength is verified with experiments, and calculated values agree well with experimental ones. Bond stress-slip constitutive relation between steel and recycled concrete was established. The calculated values are compared with the experimental values, and both are in good agreement. [ABSTRACT FROM AUTHOR]

： The curves of average bond stress versus slip between reinforcing bars (rebar) with different reinforcement corrosion rates and recycled concrete were recorded during beam tests conducted in this research program. The influence of reinforcement corrosion rate on the bond-slip performance was analyzed. The results show that the splitting failure occurs when the rebar corrosion rate is zero and 1% while the pull-out failure occurs when the corrosion rate is 9%. Splitting and pull-out damages both occur when the corrosion rate is 3% and 6%. The bond strength rises first and then drops along the increase of the rebar corrosion rate. The bond stress reaches the maximum when the corrosion rate is 1%. The bond stress concentrates at the loading end when the corrosion rate is zero and 1%，and the bond stress spreads towards the free end with the increase of corrosion rate. The peak slip increases faster with the increase of the corrosion rate. On the basis of the test data，the position function showing the distribution of bond stress was fitted and the bond-slip constitutive equation was established. [ABSTRACT FROM AUTHOR]

The effect of steel slag fine aggregate replacement percentage and compressive strength on the prism strength, peak strain, elastic modulus, Poisson ratio and stress-strain relationship of steel slag concrete were studied, through the uniaxial compression test of 6 groups of prism specimens with dimensions of 150 mm×150 mm×300 mm. The results show that steel slag concrete has the highest strength and best performance when the steel slag replacement percentage is 60%. Although the elastic modulus shows gradually increasing with the increase of the steel slag fine aggregate replacement percentage, the incensements decrease with the replacement percentage. For the steel slag concrete with the same strength, the ultimate strain decreases with the increase of replacement percentage. The relationship between the peak strain and the replacement percentage, ultimate stress of steel slag concrete is obtained by linear regression of test data. The effect of steel slag replacement percentage on Poisson's ratio is considerable. The predicted results agree well with the experimental results according to the comparison of non-dimensional full stress-strain curves. [ABSTRACT FROM AUTHOR]