Nonlinear constitutive relations are discussed for analyzing the stress distribution , the appearance and development of the cracks , as well as the behavior of the boundary conditions of the two way slabs respectively . in the light of the experimental research on r . c . two way slabs under static loading , the behavior of yield line , the load deformation curves and the crack yield , plastic limit loads of slabs with different supporting conditions are studied 根据反映双向板混凝土材料非匀质性的本构关系，分析了双向板在荷载作用下的变形、屈服、裂缝和破坏的形态特性，并对钢筋混凝土双向板在不同支承条件下的塑性极限荷载、正常使用挠度(曲线)和截面设计作了进一步研究。
Plastic theory suggests , the composite beam for the floorslab is suited lower flange , it s plastic limit moment cuts down by 52 . 4 % than the composite beam for the floorslab is suited on the top flange . it s plastic limit moment lifts 8 . 8 % than the steel beam , which is on the same condition 塑性理论分析的结果表明，楼板位于钢梁下翼缘形式的组合梁和楼板位于钢梁上翼缘形式的组合梁截面相比较，其塑性极限弯矩降低52 . 4 ，和同等条件下纯钢梁截面相比较，楼板位于钢梁下翼缘的组合梁塑性极限弯矩提高8 . 8 。
Based on the method of limitation analysis of soil plasticity , researching from the soil arching mechanism of soil - nailing retaining , the upper limit of the critical height of soil - nailing slopes and the minimum horizontal length from coping of the potential slide surface to the edge of deep excavation are obtained through the analysis to weight of soil and vertical loading and the mechanism of soil and soli - nailing acting reciprocally 摘要基于土的塑性极限分析方法，以均质土坡为例，从土钉支护结构的准粘聚力理论出发，综合考虑土体自重、坡顶的条形荷载，以及土钉与土体的相互作用的机理，推导出了土钉支护的临界高度的上限值和潜在螺旋曲线滑动面在坡顶方向距基坑边沿的最小水平距离解析表达式，可供基抗支护设计参考。
This paper makes the attempt to introduce the plastic limit analysis to the determination of the load carrying capacity of structures with defaults or / and cracks . common formulae for the determination of the lower and upper bounds of limit load are derived , then a successive iterative algorithm , based on the optimization and finite element method , to calculate the bounds is proposed , which could be applied to general structures 本文将塑性极限分析应用于含裂纹结构的极限承载能力的确定，研究和推导了一般含裂纹结构极限载荷的确定方法和普遍计算格式，提出了一种求解极限载荷的迭代算法，并就若干含裂纹结构进行了求解，给出了有意义的结论。
Third , a theoretic approach based on total theory of plasticity is for the first time applied to analyze elastoplastic torsion rigidity of the tubular , and the results are well proved by the test data . also for the first time , the plastic stability of the spiral skew stiffening shell is studied . it is shown in the experiments that there is the comparability between the stability of the members at plastic limit and that of the thin - shelled steel tubular with the spiral skew stiffening concrete rib 本文首次分析了扭转作用下的螺旋斜向加劲壳的塑性稳定性问题，还根据试验观象的观察，对构件在塑性极限时的状态，简化为内壁衬朽螺协刹向加劲混凝土肋的薄壁钢管的塑性稳定问题，利用塑性壳体稳定理论进行了探讨。
The effect of different sizes of sections , modes and values of residual stresses are studied . through the analysis , the conclusion is arrived at that the universal slenderness ratio should be used to better correlate the stability of box section beams with the member length instead of the out - of - plane slenderness , and the stability coefficient is taken to be 1 . 0 for practical used box girder . then , the elastic critical loads of box section beam - columns are obtained based on the gjelsvik theory , and the relationship between axis force p and moment m is given 最后，运用ansys通用有限元程序的beam189单元，引入初弯曲和残余应力的影响，用考虑几何和材料双重非线性的有限元求解格式求得箱形柱在不同轴力和弯矩比例作用下的弹塑性极限承载力，通过对十几个不同截面尺寸构件在不同长细比下的承载力计算，发现在轴力p远大于弯矩m时，构件将是平面外失稳控制，而当轴力p远小于弯矩m时，构件则以平面内失稳为主。
Based on the analysis of mechanism for joint region , the " frame - wall " and " aslope compression stub column " mechanical models and yielding patterns of core zone of the joints are set up . the shear load - carrying formulation for joint core zone is also given in terms of plastic ultimate analysis . and then , the comparisons between the formulas given in this paper and that of chinese design code ( draft ) and nonlinear fem as well are presented 对节点核心区的抗剪，通过受力机理的分析，建立了钢“框架剪力墙”加混凝土“斜压短受力体系及其屈服机制，根据塑性极限分析，给出了节点核心区抗剪承载力计算的迭加公式， 《规程》公式和非线性有限元近似模拟分析结果进行了比较。
