该文力求寻找一种高效准确检测混凝土构件永存应力的方法.基于声弹性理论提出了一种双横波声速法检测单向受压混凝土构件永存应力的方法,该方法通过测试受力构件第一波速和第二波速,以第一波速和第二波速的平方差为基础构建综合声学参数来检测单向受压混凝土构件永存应力.所述第一波速为声波传播方向与应力方向垂直、质点振动方向与应力方向平行的横波波速,第二波速为声波传播方向及质点振动方向均与应力方向垂直的横波波速.实验结果显示,该声学参数用于检测混凝土单向受压构件永存应力的效果与使用单一声速参数相比,对应力的敏感性有所提高,受混凝土黏滞性及材质离散性的影响更小,并且测试结果基本不受温度和湿度变化影响.

模糊综合评价法是一种基于模糊数学的综合评判方法.本文针对美学评价的影响因素具有模糊性这一特征,运用模糊数学的理论,对马鞍山大桥进行美学论证,将桥梁景观影响因素分成若干个指标,建立了评价指标集、隶属函数和权重集,通过层次分析法计算评价指标的权重集,由加权平均模糊算子对评价指标作综合模糊运算,评价大桥整体景观.实例表明:模糊综合评价方法可操作性强、效果较好,可在桥梁景观评价中广泛应用,同时从科学的角度证实了马鞍山大桥美学设计的成功.

Besides the conventional loads,the accidental loads should be considered on the safety design for the concrete filled steel tube(CFST),and one of accidental events is the lateral impact.According to the stress state of concrete and steel,the constitutive model of RHT is used for the concrete,and that of John-Cook is used for the steel.The damage evolution rules for the inner concrete are studied using the dynamic finite element software of AUTODYN,in the conditions of the impact varied with mass,velocity and the position contacted with CFST,and different restrained types at the ends.The results show the damage begins from the contact position between the impact and the CFST,and develops toward the bottom of an impact position and the restrained end.During the interaction between the impact and the CFST,the strong damage zones are also generated near the restrained end and the zone of maximum deflection.There is a strong damage zone in the upper concrete near the impact position;and the damage characteristics at the end are decided by the restrained type: the strong damage zone lies in the restrained region for the simple support end,and lies outer for the clamped support;the damage distribution in the maximal deflection is controlled by the relative position between the impact and the center of CFST and the restrained type at the end.The inner energy absorbed by concrete increases with velocity,the weight of impact,and the horizon distance between the impact position and the center of CFST.There is a larger plastic strain near the impact position,which may decrease the capacity of resist compression for the impacted CFST.The results are significant to assess the residual capacity of CFST suffered from the lateral impact.