开孔钢筋混凝土板的静力与冲击性能数值分析

采用有限元软件ANSYS,建立了开孔钢筋混凝土板模型,对不同孔洞位置和大小的钢筋混凝土板在静力和冲击荷载作用下的挠度、应力以及动力响应进行了研究,得出的结论为楼板开洞时在洞口周围合理、有效地配筋提供了依据。     

竖向荷载下桩筏基础通用分析方法

根据已有的竖向荷载下刚性板桩筏基础分析结果提出了一种竖向荷载下桩筏基础的通用分析方法。桩筏基础分析中考虑了4种相互作用,分别为桩–土–桩、桩–土–板、板–土–桩和板–土–板相互作用。筏板分析采用有限单元方法,以厚薄板通用四边形等参单元进行分析。该方法可以分析由任意桩长、桩半径和刚度特性的桩群以及任意厚度和几何外形的筏板组成的竖向受荷桩筏基础。应用该方法不需要划分桩土体单元,其分析复杂程度基本等同于弹性地基板基础,且分析过程简洁。通过与各种方法的比较证明该方法是合理可行的,精度上也满足要求。     

桩基工程静载检测技术应用分析

结合工程案例,对桩基静载检测技术、试验方法进行了探讨,为了保证静载试验检测数据的真实、有效,对影响数据准确性的主要因素及相应的解决措施进行了研究,总结了试验安装过程中的注意事项,以确保试验的准确性。     

静力及低周往复荷载作用下端板连接的力学性能研究

由于端板连接节点的多样性,不同构造形式端板连接节点力学性能存在一定差异.有限元分析方法可以通过变化多组几何参数建立大量模型来研究连接节点受力性能,是有效的研究方法之一.在已有试验模型基础上,衍生了一系列端板连接节点有限元模型,考虑材料非线性、几何非线性以及构件之间接触引起的状态非线性影响,对有限元模型进行静力和低周往复荷载计算.计算结果与试验进行了比较,验证了有限元模型的可靠性和有效性,并研究了构造形式对端板连接节点力学性能的影响.     

Behavior of post-installed shear connectors under static and fatigue loading

This paper describes a series of tests investigating methods to develop composite action in existing non-composite floor systems. Three types of 22-mm diameter post-installed shear connectors were tested under static and fatigue loading. Test results are compared with previous research results on 19-mm diameter, post-installed shear connectors as well as with conventional welded shear studs. Based on the test results, preliminary design equations are proposed for the static and fatigue strength of post-installed shear connectors. These post-installed shear connectors showed a significantly higher fatigue strength than conventional welded shear studs. The superior fatigue strength of these post-installed shear connectors enables the strengthening of existing bridge girders using significantly fewer shear connectors than possible with conventional welded shear studs.     

纯压抛物线拱平面内稳定性及设计方法研究

采用大挠度弹塑性有限单元法对全跨竖向均布荷载作用下纯压抛物线拱平面内稳定承载力进行研究,考虑材料非线性、焊接残余应力、初始几何缺陷、矢跨比和支承条件等因素的影响,得到了热轧圆管截面、焊接工字形截面和焊接箱形截面纯压三铰、两铰和无铰抛物线钢拱的平面内稳定性设计曲线,给出纯压抛物线钢拱的平面内稳定设计公式。以拱的正则化长细比为基本参数,统一了三铰、两铰和无铰纯压抛物线钢拱的平面内稳定设计曲线,可用于全跨竖向均布荷载作用下纯压抛物线钢拱的平面内稳定性设计,同时可供实际设计时使用和制定有关规程时参考。     

桩靴在静载荷作用下的沉降预测

为了研究桩靴在静载荷作用下的沉降,基于圆孔扩张理论,推导出桩靴在荷载作用下的桩端阻力表达式.将桩端阻力作为桩靴受压状态下的荷载传递函数,结合桩侧摩阻力函数,采用分段位移迭代算法进行计算,预测出桩靴在受压状态下的荷载—沉降曲线.开展砂土中的桩靴静载模型试验,将模型试验结果与理论结果进行对比验证.结果表明:推导的理论公式计...     

混凝土T梁静载试验研究

为了检验施工质量是否符合设计要求，保证桥梁的安全性，对某T梁进行了静载试验，介绍了T梁的试验方法和测试手段，通过试验数据分析，对T梁的质量做出正确的评定，为该桥的正常运营提供了可靠的试验依据。     

Non-linear plastic analysis of steel arches under lateral buckling

Curved graphs are proposed that relate the shape of the box cross-section of an arch to the real ultimate lateral strength for various values of length, support conditions and of height of the cross-section.The real ultimate lateral strength of a series of arches is determined and the results obtained are then compared to those provided by Sakimoto and Komatsu [1].Elastic–plastic steel material and geometric non-linearity hypotheses, residual stresses, and initial lateral deflection are all taken into consideration with respect to the real ultimate lateral strength.     

Behaviour of concrete-filled steel tubes under static and variable repeated loading

This paper presents the results of static loading (SL) and variable repeated loading (VRL) tests on concrete filled steel tubular (CFST) columns. Assessment of the columns was based on its length, concrete strength and load eccentricity. The column behaviour (with and without filling) from the tests was studied. The ultimate strength of the columns subjected to VRL reduced by up to 16% after undergoing a number of load cycles. The incremental collapse (IC) limit was found to lie between 70% and 88% of the static collapse load for CFST columns. The deformations at IC limit were significant and could affect practical designs. The theoretical strengths of the stub and long columns tested are determined on the basis of building code 318 of the American Concrete Institute, and compared with the test results. The squash load equation of the code was found to underestimate the nominal strength of short composite columns.     

Performance of tunnel support under large deformation static and dynamic loading

Tunnels under high stresses and deep mining conditions are often subjected to large static and dynamic deformations. It is usually not practically possible to contain the energy involved by means of stronger support. Instead, the support must yield and, in yielding, absorb energy. With yielding support of suitable deformation capacity, it should be possible to contain very severe static and dynamic deformations. Research into the performance of tunnel support has recently been carried out in three areas: (1) the behaviour of retainment support elements such as rockbolts under dynamic loading. This showed that specially designed yielding rockbolts could absorb more than 50 kJ each in yielding some 0,5 m, without showing any damage, (2) the energy absorbing capacity of mesh and fibre reinforced shotcrete, based on the results of static testing of shotcrete panels, and (3) the behaviour of containment support elements, such as wire mesh, wire rope lacing and reinforced shotcrete under dynamic loading. This has shown that the practical capacity of wire mesh alone is about 15 kJ/m², but that this capacity is more than doubled when wire rope lacing is added.     

浅谈静压法沉桩在桩基础中的应用

阐述了静压法沉桩的适用范围,就如何判断静压法的沉桩阻力作了探讨,提出了静压法沉桩施工的注意事项,对常见质量事故产生的原因进行了分析,同时提出了相应的处理措施,指出静压法沉桩具有无噪声、无振动、无冲击力等优点,值得推广使用。     

钢桁架桥静力分析及地震荷载响应分析

在有限元分析软件ANSYS环境下,对建立的有限元模型某钢桁架桥的桥体在静力的作用下进行节点的位移分析。同时,在该桥体侧向施加地震谱,分析该结构的地震荷载响应,并得出一些结论。     

ANN-based empirical modelling of pile behaviour under static compressive loading

Artificial neural networks have been widely used over the past two decades to successfully develop empirical models for a variety of geotechnical problems. In this paper, an empirical model based on the product-unit neural network (PUNN) is developed to predict the load-deformation behaviour of piles based SPT values of the supporting soil. Other parameters used as inputs include particle grading, pile geometry, method of installation as well as the elastic modulus of the pile material. The model is trained using full-scale pile loading tests data retrieved from FHWA deep foundations database. From the results obtained, it is observed that the proposed model gives a better simulation of pile load-deformation curves compared to the Fleming’s hyperbolic model and t-z approach.     

高强钢筋高强混凝土梁静力和疲劳性能试验研究

通过9根配有新Ⅲ级钢的高强混凝土梁和4根配有Ⅱ级钢的混凝土梁的静载和等幅疲劳荷载试验,分析研究了高 强混凝土梁的变形性能和疲劳特性。试验结果表明,在高强混凝土梁中应用高强钢筋,可以使两者的性能得以充分发挥, 不仅承载力大幅度提高,而且能较好的满足正常使用极限状态的要求。高强混凝土受弯构件在疲劳荷载作用下刚度降低, 裂缝宽度增大,其变化规律和受压区混凝土应变的增加规律基本一致。疲劳荷载作用N次后构件的裂缝宽度,可根据初 始裂缝宽度和受压区混凝土应变增长系数来计算。根据试验分析,得到了高强混凝土梁在疲劳荷载作用下的截面应力、裂 缝宽度及高强钢筋S-N曲线试验回归公式,可为高强混凝土梁设计提供一定的参考。     

深层平板静载荷试验和低应变反射波法的应用

指出随着桩基检测技术的不断发展,深层平板静载荷法和低应变反射波法作为一种行之有效的桩基检测方法已经得到了广泛的应用,结合某科研中心人工挖孔墩验收检测实例对其进行论述,以指导类似工程施工。     

Ant colony optimisation of spatial steel structures under static and earthquake loading

Optimisation is the process of trying to find out the best possible solution to any problem satisfying constraints. Soft computing is the class of methods which have been inspired by the biological computational methods and nature's problem-solving strategies. Currently, these methods include neural networks, evolutionary computational models such as genetic algorithms, random cost and linguistic models such as fuzzy logic. Ant colony optimisation (ACO) is one such method applied for large engineering combinatorial optimisation problems. A design procedure utilising an ACO technique is developed for discrete optimisation of reticulated steel space trusses. The ACO algorithm is motivated by the analogy with natural phenomena, in particular the ability of a colony of ants to ‘optimise’ their collective endeavours. In this paper, the computational implementation of ACO is presented in a structural design context. The objective function considered is the total weight/cost of the structure subjected to material and performance constraints in the form of stress and deflection limits. In the case of reticulated space trusses, the design variables are the cross-sectional areas of members belonging to various groups. The objective function and constraints are obtained by using structural analysis package FEAST (Anonymous, 1995. FEAST user manual. Trivandrum, India: SEG, SDS Group, ISRO, VSSC) in case of structures subjected to static loading and SAP90 (Anonymous, 1990. SAP90, ETABS, SAFE – computer software for structural and earthquake engineering. Berkeley, CA: Computers and Structures) for earthquake loading for reticulated steel space trusses. The numerical examples presented demonstrate the computational advantage of the ACO for large-scale optimisation problems.     

Numerical simulation of Brazilian disk rock failure under static and dynamic loading

A numerical simulator based on RFPA (Rock Failure Process Analysis) is used to study the deformation and failure process of a Brazilian disk of heterogeneous rock when subjected to static and dynamic loading conditions. In this simulator, the heterogeneity of rock is considered by assuming that the material properties of elements conform to a Weibull distribution; an elastic damage-based law that considers the strain-rate dependency is used to describe the constitutive law at mesoscopic scale; and a finite element program is employed as a basic stress analysis tool. The simulator is firstly validated by simulating the dynamic spalling of a homogeneous rock bar and by comparing with the theoretical and experimental results. Then, the failure process of a Brazilian disk of rock subjected to static and dynamic loading is numerically simulated, and the numerical results are compared with the available experimental results. Particular attention is given to the typical failure patterns of the rock disk when the incident compressive stress waves with different amplitudes are applied. The numerical simulation also identifies the failure mechanisms of rock during dynamic failure processes that are closely related to the propagation of the stress wave.     

Deformation analysis under variable loading

The inelastic analysis of strain hardening and elastoplastic frame structures under variable loading is presented. The formulation adopted is essentially that proposed by Maier who, using an ‘imposed rotation’ method within a modern matrix framework, reduced the final mathematical form to a linear complementarity problem (LCP). The nonproportional loading path is subdivided into a set of individually proportional stages — the basis of the ‘multistage method’. Under the assumption of holonomic behaviour, the LCP within each loading stage is solved through Hildreth's modified Gauss-Seidel iterative procedure. The nonholonomic nature of plastic deformations is only allowed for in passing from one stage to the subsequent one by suitable adjustment of the assumed piecewise linear constitutive laws. Two main classes of hardening models are presented with detailed treatment of the stage updating of yield limits. A brief discussion on the specification of the appropriate hardening parameters for critical sections of essentially mild steel members is included. Finally, examples are given to illustrate both the theoretical and practical applications of the method.