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Shear deformations can affect final member-end-moments for statically indeterminate continuous beams and frame structures, though for typical civil engineering structures their effect is small and moments can be based on flexural deformations only. When a member is deep relative to span length, however, shear deformations should be considered in the analysis. This can be included in the stiffness method and in a modified form of moment distribution where the carry-over factor is less than one-half due to the added flexibility from shear. In a prior paper the first author presented a new approach for solving statically indeterminate beams and bridge frames, with final end moments given in closed-form expressions. The advantages of this new approach are that no simultaneous equations are required as in the stiffness method, moments are not distributed back and forth as in moment distribution, and manual calculations may be used which give exact results for as many spans as desired. While only flexural deformations were considered in the original paper, this paper presents a closed-form approach that has been modified to include shear deformations. Final expressions are given for continuous beams and bridge frames, providing exact member-end-moments that match results from the stiffness method when shear deformations are included in the analysis. 相似文献
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基于刚度下降建立了力学概念明晰、能涵盖截面、构件和结构三个层次的损伤指标体系,编制了相应的有限元程序,并用于对钢筋混凝土多跨超静定连续梁进行弹塑性损伤评估,表明了该方法的可行性. 相似文献
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现行国家规范(规程)仅对预应力次内力中的次弯矩和次剪力的计算方法做了规定,而对次轴力的计算并未做明确规定,只给出了相应的施工技术措施以减小超静定结构中次轴力对预应力构件的不利影响。推导了超静定结构中预应力次轴力的计算方法,并分析了柱截面刚度、梁的弹性模量和截面面积、梁跨度、层高、不同张拉方式等对其的影响。 相似文献
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A.J.M. Leijten 《Engineering Structures》2011,33(11):3027-3032
In statically indeterminate structures, connections play a vital role in the moment distribution. Demonstrated here is a method to evaluate the conditions, taking full advantage of the benefits offered by the indeterminate nature of the structures, and using the well-established, graphical beam-line method. This method shows how important the immediate load take-up is, the stiffness, the moment capacity of the connection and how it all affects the structural behaviour. The examples considered here use both the traditional non-reinforced dowel-type fastener connections and also timber connections reinforced with steel plates. They show that the minimum rotation requirements to achieve an effective structure are satisfied easily in contrast to requirements on stiffness. In this respect, timber connections with local reinforcement glued at the interface of the connection area offer more prospects. 相似文献
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体外预应力结构弹性内力分析 总被引:1,自引:1,他引:0
约束次内力法是求解预应力超静定结构内力的一种方法。根据约束次内力法的原理 ,针对体外预应力加固工程的实际需要 ,直接给出数种预应力线型布置在三种约束下的约束次内力公式 ,并基于该方法讨论了力筋线型对体外预应力连续梁的预应力效果的影响 相似文献
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部分预应力混凝土超静定结构的设计方法 总被引:1,自引:0,他引:1
本文提出了部分预应力混凝土超静定结构的一种新的设计方法──单位次弯矩法。该法以结构中所有部分预应力混凝土构件同时满足两类极限状态为设计原则。另外,基于有效利用次内力的思想,对预应力筋的配置以及利用非吻合束等问题提出了可供实践应用的设计建议。附有设计实例。 相似文献
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以结构力学课程无纸考试为出发点,分析了主观考试题在线答题与计算机评定的难点问题,提出了引导式主观考试题型的交互答卷与自动评判的程序方法。在VB软件平台下,以图乘法计算结构位移问题为例,描述了结构力学课程主观题型在线交互答卷与成绩自动评判的程序机理,给出包括静定结构弯矩图绘制、图乘法计算结构位移、超静定结构力法与位移法求解和结构固有特性问题在线答题与自动评判实例。此研究解决了结构力学课程主观题型的无纸化考试与自动评判问题,其研究思路将为力学等工程类课程主观题型的考试与评定提供有效的程序方法。 相似文献
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Helmut Rubin 《Stahlbau》2006,75(7):578-585
Determination of warping stresses of box sections by diagrams. For determination of warping torsion for beams with box section it is sufficient to examine only points with external torsional moments. Moreover in the case of statically indeterminate systems the reaction torsional moments may be calculated neglecting warping torsion completely. This contribution allows the determination of normal and shear stresses of warping torsion by diagrams or alternatively by formulae depending only of two parameters of the section. Warping moment and secondary torsional moment must then not be calculated. The applied theory encludes secondary shear deformation, which is always necessary in the case of hollow sections. 相似文献
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采用改进的局部变形模型,对纤维增强复合筋超静定混凝土梁的抗弯性能进行研究。首先提出一个模型并将其性能与由FRP筋加固的简支及连续混凝土梁的试验结果进行对比。然后将模型应用到FRP筋连续梁中来预测弯矩分布,以及弯曲裂缝的形态,包括裂缝间距和裂缝宽度。尤其是该模型具有在梁中的高应变区确定变形的能力。基于理论分析结果,通过比较FRP筋增强的梁与普通钢筋混凝土梁,阐述了混凝土梁的延性和超载性能。所有的结果和相关解释均取决于某些特定假设和模型中的输入参数,尤其取决于FRP筋和混凝土之间的粘结性能。 相似文献
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随着高层结构应用日益广泛,多肢剪力墙及其组合结构成为高层结构中不可或缺的一部分,但是在土木类规范、教材中对于多肢剪力墙内力求解的核心部分:对连梁约束弯矩构成的微分方程组采取叠加分配的计算方法有失偏颇。文章对连梁约束弯矩求解过程中产生的2个二阶微分方程组采取转化为4个一阶微分方程组,进而求微分方程组系数矩阵的基解矩阵的办法,从而给出多肢剪力墙中三肢剪力墙在3种水平荷载作用下内力、位移的解析计算公式。比较两种方法的内力计算结果与Midas计算模型内力的差距,发现运用传统方法连梁的内力结果较计算模型和文中计算小10%左右。该方法避免对连梁刚度以及连梁相对位置和墙肢整体性等一系列参数的讨论,避开分配系数这个概念,改进传统解析方法,为剪力墙与框架组合结构内力、位移解析表达式的推导夯实基础。 相似文献
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This paper deals with the reliability assessment of steel frame planar structures using the probabilistic method SBRA (Simulation‐Based Reliability Assessment) documented in [1]. The advances in computer technology make it possible to utilize the potential of the SBRA method not only for the reliability assessment of simple structures and their components but also for the reliability assessment of more complex, statically indeterminate frame structures. In this connection attention is paid to an alternative way of the local and global stability check based on the SBRA method applying the second order theory. 相似文献
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Rational approach for the analysis of segmental reinforced soil walls based on kinematic constraints
The paper presents an analytical method for the solution of reinforced soil walls in which the wall facing has a structural role. The three-component (soil–reinforcement–wall) system is statically indeterminate, and hence cannot be solved by equilibrium equations alone. The paper follows up on the work of Baker and Klein [2004. An integrated limiting equilibrium approach for design of reinforced soil retaining structures part I – formulation. Geotextiles and Geomembranes 22, 119–150] where an interaction model, incorporating factors that divide forces between the reinforcement layers and the wall, was introduced to solve the statically indeterminate system. In the current work, the division factors are resolved such that the kinematic constraints of compatibility between the reinforcement layers and the wall are satisfied. This is achieved by solving an optimization problem in which the objective function includes the relative displacement between the reinforcement layers and the wall. The resultant system is fully coupled whereby upper reinforcement layers are affected by the behavior of lower layers. As such, the method overcomes the limitation of the original framework in which the top-down procedure omits such coupling. A non-dimensional parametric study was conducted on walls with 10 face blocks (9 reinforcement layers). Results are given in a normalized manner for cases in which the reinforcement pullout stiffness is uniform and linearly increasing with depth. Analysis results show that in cases where the wall is relatively stiff compared to the reinforcement, the upper reinforcement layers are clearly affected by the lower layers (this is a direct outcome of the fully coupled system). On the other hand, when the relative stiffness of the wall is low, the system behavior tends towards that of a hinged system, which is statically determinate. In this case the solution becomes independent of the reinforcement pullout stiffness. Analysis results indicate that current design codes, which do not explicitly consider the structural role of the facing in the calculation procedure, may be overconservative in certain cases. This result supports the argument for introducing the structural role of the facing into design procedures. 相似文献
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以直线布筋的两跨连续梁为例,探讨了预应力次弯矩的产生机理,从预应力束的截面偏心距的合理取值、合理布置、有效预应力的提高三方面介绍了次弯矩在预应力混凝土超静定结构中的合理利用,以供借鉴应用。 相似文献