起重机加筋翼缘板的局部屈曲数值仿真分析

针对起重机柔性肋加筋翼缘板的局部屈曲失稳问题,以承受单向轴压的四边简支加筋矩形板为分析对象,采用有限元数值方法,研究加筋板在文献[1]的约束方法下,长宽比β、抗弯刚度比γ、面积比δ对屈曲系数k的影响。将得到的结果与Timoshenko能量法进行对比,验证了有限元数值仿真法的正确性。对比研究截面积相同但纵向构型不同的加筋肋在相同配筋方式下对简支矩形板的加强作用。结果表明:当长宽比β=1.67时,T型肋加筋板屈曲系数比矩形肋加筋板屈曲系数大54.8%;角型肋加筋板比矩形肋加筋板大32%。

基坑钢围檩极限承载能力研究

在基坑中,钢支撑的极限承载能力与围檩的受力密切相关。通过精细化数值计算方法研究钢支撑系统特殊节点构造中围檩的极限承载能力。结果表明,伺服支撑直接作用下围檩极限承载力随偏心距增大而降低;伺服系统的端头圆板构造,较钢支撑直接作用下钢围檩的承载力小很多,设置钢垫板以及加密加劲肋可提高端头圆板模型承载能力。总结的经验可供类似工程参考。

基坑钢支撑斜牛腿极限承载能力研究

在基坑中,钢支撑的极限承载能力与斜牛腿的受力密切相关。特别是在伺服系统中,由于与斜牛腿相连的伺服系统端部圆板直径较小,极易产生应力集中而导致斜牛腿钢板屈服破坏。通过精细化的数值模拟计算方法,研究钢支撑系统特殊节点构造中斜牛腿的极限承载能力并进行相应的结构优化设计。结果表明:由于伺服系统端部圆盘直径较小,原结构承载板中部容易发生凹陷,通过缩小承载板间距可使荷载能均匀作用在加劲板板上,从而提高斜牛腿的承载能力;增加承载板板厚至25 mm、加宽肋板以及增大伺服系统端部圆板的尺寸,均能有效提高斜牛腿的承载能力。

Experimental study on mechanical property of stiffening-ribbed-hollow-pipe cast-in place reinforced concrete girderless floor

Stiffening-ribbed-hollow-pipe cast-in place reinforced concrete girderless floor is a new-style hollow girderless floor system. Model experimental researches of simply-supported floor and four-corners bearing floor have been done on this new kind of floor system in this paper. The experiment results show that the floor system has good mechanical property such as high bearing capacity, big rigidity and good tensility. A theoretical method is presented in this paper that the stiffening-ribbed-hollow-pipe girderless floor can be analyzed by being converted equivalently to orthotropic solid slab. It is indicated that the method is correct and reasonable according to the contrast between theoretical calculated results and experimental measured results. The theoretical results coincide with the measured results well.