无支撑半刚性连接钢框架的简化分析

用变刚度的螺旋弹簧模拟梁柱节点半刚性连接的弯曲特性 ,建立了半刚性连接钢框架梁单元的刚度矩阵。通过分别引入横梁修正线刚度和修正转动刚度 ,将等效代替框架法和无剪力分配法推广应用于无支撑半刚性连接钢框架的结构分析 ,其计算十分简便     

半刚性钢框架优化设计研究

推导了考虑连接柔性和几何非线性的局部坐标下的单元刚度矩阵,并对半刚性连接单元的固端力进行了修正;其次,采用增量加载法,给出了考虑连接柔性、框架的几何非线性和单元内力与连接之间耦合效应的半刚性钢框架结构分析计算机流程;按照GB50017-2003《钢结构设计规范》和实际施工的要求,建立了考虑构件和连接最小费用问题的半刚性钢框架优化数学模型;然后,在遗传算法和半刚性钢框架结构分析流程的基础上,给出了半刚性钢框架优化设计步骤;根据算例,对半刚性钢框架优化设计做了初步的探讨。     

半刚性连接钢框架简化分析的无剪力分配法

通过引入螺旋弹簧刚度 ,推导了半刚性连接梁单元的弯矩转角方程和修正转动刚度 ,并将无剪力分配法推广应用于半刚性连接钢框架的结构分析 ,其计算十分简便 ,可供工程设计人员应用     

水平荷载作用下足尺半刚性连接组合梁框架试验

为研究半刚性连接组合梁钢框架在水平荷载作用下的特性,进行水平荷载作用下足尺的空间两层两跨半刚性连接组合梁框架的试验研究。半刚性连接组合梁框架由热轧H型钢柱和焊接H钢梁及压型钢板混凝土组合梁组成,连接为平端板连接半刚性节点。试验主要进行相应测点的应变、转角及位移测量,框架整体性能及半刚性连接节点性能的分析。试验结果显示半刚性连接组合梁框架具有较强的抵抗水平荷载的能力;平端板连接组合节点为半刚性连接、部分强度节点,具有较高的强度、刚度和较好的延性。将试验结果与简化计算方法的预测结果进行比较,结果显示框架的总体位移、极限承载能力、节点转动能力及强度的试验值与简化方法的预测值能较好的吻合。     

The stiffness estimation of steel semi-rigid beam-column moment connections in a fire

This study investigates the estimation of the stiffness of steel semi-rigid beam-column moment connections in a fire. The general purpose finite element software ANSYS is adopted. The parameters, such as material properties and geometric conditions, are fully studied to investigate their effect on stiffness. The formula for the stiffness of steel semi-rigid beam-column moment connections, which are made with the H-beam and H-column, for the case of constant temperature with increasing vertical beam load is proposed and verified by the results of ANSYS analysis. The stiffness of steel beam-column connections for the case of increasing temperature with constant load estimated by the proposed formula is found to be conservative.     

火灾中半刚性型钢梁柱节点的刚度分析

采用通用有限元软件ANSYS,研究火灾中半刚性型钢梁柱节点的刚度,分析材料特性、几何条件等参数对刚度的影响。恒温下,梁上竖向荷载变化时,提出H型梁柱节点的刚度公式,并用ANSYS分析结果进行验证。恒载下,温度变化时,节点的刚度公式偏保守。     

半刚性连接钢框架-钢板剪力墙结构抗震性能试验研究

通过对半刚性连接框架-钢板剪力墙结构在水平反复荷载作用下的试验研究,得到了结构的滞回曲线、延性指标、水平刚度、梁柱应变、转角及各关键部位的变形。从耗能能力、刚度退化、承载力、延性等方面分析该种结构的抗震性能和耗能机理;依据应力分布、梁柱转角研究半刚性节点与钢板剪力墙的相互影响效果;分析结构的内力转换和破坏模式。结果表明：该结构具有良好的延性和耗能性能;半刚性节点在反复荷载作用下没有明显变形,节点刚度退化小,框架和钢板剪力墙协同工作良好;梁柱半刚性连接弱化了结构的整体刚度,框架自身承担的水平荷载有限;破坏模式为内填钢板剪力墙局部撕裂,拉力带作用明显,钢框架柱脚及梁柱半刚性连接部位形成塑性铰,框架整体呈弯曲破坏模式。图12表4参10     

The effect of axial beam force on moment–rotation curve of top and seat angels connections

Bolted top and seat angle connections are mainly designed to sustain gravitational loads of simply supported steel beams. However, the inherent flexural resistance of such connections may not be ignored when an accurate analysis of semirigid steel frames is desired. Current research aims at studying moment–rotation behaviour of this type under combined moment and axial tension force. Several refined three‐dimensional finite element models are created based on the previous experimental studies, and their accuracy is examined trough a comparison to test results from previous experimental studies. This study showed that the axial tension force reduces the connection initial stiffness and moment capacity. Based on the results obtained from analysing a series of finite element models under combined axial tension and moment loading, an equation is presented to estimate the affected moment–rotation response of such connections in terms of the connection geometrical properties, its moment–rotation response in the case of zero axial force and an expected axial tension force. Copyright © 2009 John Wiley & Sons, Ltd.     

A simplified analytical method for unbraced composite frames with semi-rigid connections

The original Muto’s method for the lateral force analysis of conventional unbraced bare steel frames is first modified to incorporate the effects of semi-rigid beam-to-column connections. From which, equations for the calculation of the inter-storey drifts of these frames are formulated using first principles. By comparing the frame analytical results calculated from a rigorous finite element programme, it is shown that the proposed method gives reasonably accurate internal forces and inter-storey drifts estimations of a sway bare steel frame with semi-rigid connections. The proposed modified Muto’s method is then further developed for the manual analysis of unbraced composite frame systems by introducing an improved equivalent beam stiffness to account for the variation of the beam stiffness in the hogging and sagging moment regions. The accuracy of this simplified analytical method is verified by the rigorous finite element analysis of an unbraced composite frame with semi-rigid connections. Last, a parametric study is conducted to quantify the effects of semi-rigid connections on the inter-storey drifts of unbraced composite frames under lateral loads.     

半刚性连接钢框架的弹性屈曲荷载计算

以单层多跨框架结构为研究对象,通过对各梁柱构件建立失稳状态的控制微分方程并引入相应的连续性条件和边界条件,建立了半刚性连接平面钢框架结构整体弹性失稳的临界荷载计算模型,并研制了相应的计算程序。计算结果表明,框架结构的半刚性连接特性和水平支撑对其整体稳定性的影响极为显著,而且结构失稳的整体效应需引起高度重视。分析结果还表明,作用于多跨框架结构竖向荷载的分布特征对整体框架结构的弹性屈曲荷载有不可忽视的影响,而这一点在目前钢框架的设计理论中并未充分考虑。另外,半刚性连接特性及结构的支撑刚度对钢框架结构稳定性的影响具有明显的界限性和区间性,即当连接刚度或支撑刚度超过一定数值时,其变化对框架结构弹性屈曲荷载的影响将无需再考虑。     

Numerical study of built-up double-Z members in bending and compression

The use of the finite element method (FEM) for the design of composed, thin-walled, structural steel members is considered. The bolted double-Z frame member is an interesting and economical engineering solution, already used in practice [1]. However, the European recommendations for the design of steel structures do not consider built-up members from cold-formed steel profiles. Finite element analysis is used to capture the various buckling effects that shape the response of slender thin-walled members. From the finite element model, the importance of initial imperfections and stiffness of connections is identified. The experimentally validated model predictions show that a non-linear finite element analysis can predict the member behaviour, in terms of failure mode and ultimate load, yield line pattern, overall stiffness and local strain in the cold-formed profiles. To obtain a good prediction, overall and localised initial imperfections should be considered and included in the analysis.     

Second-order distributed plasticity analysis of steel frames with semi-rigid connections

This paper proposes an accurately and efficiently numerical procedure for distributed plasticity analysis of semi-rigid steel frames. Both geometric and material nonlinearities are included in the proposed analysis. Geometric nonlinearities due to the large and small P-Delta effects are respectively captured using the corotational formulation and curvature-based displacement procedure. Material nonlinearities due to residual stresses and inelastic behaviour of materials are taken into account using a fibre model. The nonlinear semi-rigid behaviour of beam-to-column connections is simulated using a zero-length connection element. The validity of the present analysis is verified by comparing the obtained predictions with existing solutions. A case study of a very large-scale steel frame indicates that the present analysis is very reliable and computationally efficient and thus would be a valuable tool for daily use in office engineering design.     

半刚性节点钢框架侧移限值的可靠性分析

工程中多层钢框架结构经常采用半刚性连接形式,将半刚性连接节点视为弹簧单元,用蒙特卡罗模拟法,对半刚性钢框架进行了基于侧移的可靠性研究。通过各算例探讨了节点刚度对多层钢框架可靠性的影响。     

半刚性连接钢框架二阶内力和位移的简化计算

框架中梁柱连接大多介于完全刚接与理想铰接之间,即半刚性连接。提出了半刚性连接钢框架二阶内力与位移的简化计算方法。在计算内力时用弯矩放大法,连接的影响通过将梁的抗弯刚度乘以修正系数来考虑;计算位移时用D值法,连接的影响通过将梁的抗弯刚度转化为等效刚度来考虑。算例表明,在计算中应充分考虑半刚性连接的影响。     

连接的半刚性对钢框架结构动力性能的影响

用两端带转动弹簧的杆单元代替一般的杆单元,提出了一种新的平面杆系钢结构动力分析计算模型。通过对杆单元的转角位移方程进行修正,推导了这种计算模型的结构刚度矩阵,提出了钢框架结构弯剪型层模型考虑杆端转角后的结构侧移刚度计算方法,分析了连接的半刚性对钢框架结构动力性能的影响。算例结果表明：连接的半刚性对结构动力性能的影响非常大,不容忽视。     

半刚性连接钢框架二阶内力和位移的简化计算

框架中梁柱连接大多介于完全刚接与理想铰接之间,即半刚性连接.提出了半刚性连接钢框架二阶内力与位移的简化计算方法.在计算内力时用弯矩放大法,连接的影响通过将梁的抗弯刚度乘以修正系数来考虑;计算位移时用D值法,连接的影响通过将梁的抗弯刚度转化为等效刚度来考虑.算例表明,在计算中应充分考虑半刚性连接的影响.     

竖向荷载下半刚性连接组合框架的实用设计方法(Ⅰ)——梁柱节点设计

虽然在钢框架结构设计中考虑半刚性连接和楼板的组合效应会产生良好的结构经济性,但是在实际工程中仍很难应用,主要原因是缺乏合适简便的设计方法。本文在国内外研究的基础上,结合我国钢结构设计规范GB50017-2003,给出了竖向荷载下半刚性连接组合框架的实用设计建议方法。设计建议方法包括满足两个极限状态的节点、梁、柱设计,较好地解决了梁挠度和柱有效长度系数计算中节点连接刚度的合理选取、半刚性特征对梁挠度和柱计算长度的影响。该方法不仅反映了节点和框架的实际性能,而且简便实用,符合工程师对普通钢框架的设计习惯。本文为全文的第一部分,介绍了梁柱节点设计。     

半刚性连接钢框架水平侧移的简化计算

以一榀半刚性钢框架模型为例,在某些假定条件下,导出了其在水平荷载作用下的弹性侧移公式,并与刚性钢框架在水平荷载作用下的侧移公式进行比较,引入框架梁名义线刚度的概念,提出了在半刚性钢框架设计中采用框架梁名义线刚度来考虑连接初始刚度对框架水平侧移的影响.     

支撑节点板对铰接支撑框架体系的影响

由于支撑节点板的存在,将对铰接支撑框架结构中的梁柱节点的转动能力产生影响,梁柱节点的刚度将由铰接过渡到半刚接。本文通过ABAQUS有限元分析软件,分析了节点板的尺寸、厚度对梁柱节点刚度的影响。由于梁柱节点半刚接的影响,结构体系的整体反应及局部杆件内力都将受到影响,通过分析计算,可以发现梁柱节点半刚接对结构体系整体反应影响较小,但是对布置支撑的中间跨梁的弯矩影响则不能被忽略。     

Evaluation of connection flexibility in cold formed steel racks

Steel storage racks are three-dimensional framed structures fabricated from cold formed steel sections, wherein hook-in end connectors are used to make beam-column connections which are basically boltless and semi-rigid in nature. Different types of beam end connectors with different geometry of the connected members are available, making it impossible to develop a generalized analytical model. Only very few theoretical models are available to evaluate the performance of the joints for some typical connectors. More often experimental evaluation and numerical studies are needed to predict the behaviour of every different type of connectors. In the present study eighteen experiments were conducted on a commercially available pallet rack connection by varying the most influencing parameters such as thickness of the column, depth of the connector and the depth of the beam. The main objective of this work is to quantify the beam to column joint, flexibility of commonly used pallet rack frame and to develop a general Frye-Morris type/three parameter power model type moment versus relative rotation relationship. A companion finite element shell model that simulates the experimental behaviour closely is developed using ABAQUS finite element software, which is also used for further parametric studies. Using the three major variables as size parameters, a Frye-Morris type of equation has been proposed. Some calibration studies have also been carried out. Using the ultimate moment capacity, initial connection stiffness and the shape parameter obtained, a three parameter power model has also been proposed to represent the moment-rotation behaviour of the boltless connections.