蒙皮支撑柱的静力性能分析

本文提出了蒙皮支撑柱在静力荷载作用下的几何非线性有限元分析方法。钢构件、蒙皮和连接件分别被离散成空间薄壁开口截面梁柱单元、等效正交各向异型板壳单元和连接单元。采用修正的拉格朗日描述建立结构的非线性平衡方程,利用柱面弧长增量法并在每一增量步中采用修正的牛顿·拉夫逊方法进行迭代来跟踪平衡路径。通过试验对该方法进行了验证并利用该方法分析了蒙皮支撑Ｃ型截面轴心受压柱的基本受力性能。结果表明,蒙皮的支撑作用可以改善柱的受力性能并提高其承载能力。     

蒙皮效应在建筑结构中的研究与应用进展

对蒙皮效应的产生机理及条件进行了介绍,并基于前人的研究成果,从连接方式的性能、蒙皮体支撑构件的静力特性、蒙皮体的抗剪性能、蒙皮单元和主结构的协同工作性能及空间结构蒙皮效应5个方面对蒙皮效应在建筑结构中的研究与应用进行了梳理和总结.在前人研究成果的基础上提出,由于蒙皮的抗剪性能、板与构件之间的连接件数据不足,在目前的结构设计中没有考虑蒙皮效应的有利影响,有必要针对考虑蒙皮效应的设计方法开展进一步研究,提出更合理、简化的设计方法.     

蒙皮效应在建筑结构中的研究与应用进展

对蒙皮效应的产生机理及条件进行了介绍,并基于前人的研究成果,从连接方式的性能、蒙皮体支撑构件的静力特性、蒙皮体的抗剪性能、蒙皮单元和主结构的协同工作性能及空间结构蒙皮效应5个方面对蒙皮效应在建筑结构中的研究与应用进行了梳理和总结.在前人研究成果的基础上提出,由于蒙皮的抗剪性能、板与构件之间的连接件数据不足,在目前的结构设计中没有考虑蒙皮效应的有利影响,有必要针对考虑蒙皮效应的设计方法开展进一步研究,提出更合理、简化的设计方法.     

蒙皮效应在建筑结构中的研究与应用进展

对蒙皮效应的产生机理及条件进行了介绍,并基于前人的研究成果,从连接方式的性能、蒙皮体支撑构件的静力特性、蒙皮体的抗剪性能、蒙皮单元和主结构的协同工作性能及空间结构蒙皮效应5个方面对蒙皮效应在建筑结构中的研究与应用进行了梳理和总结.在前人研究成果的基础上提出,由于蒙皮的抗剪性能、板与构件之间的连接件数据不足,在目前的结构设计中没有考虑蒙皮效应的有利影响,有必要针对考虑蒙皮效应的设计方法开展进一步研究,提出更合理、简化的设计方法.     

蒙皮支撑C型檩条的有限元分析

本文借助有限元软件ANSYS对蒙皮支撑简支C型檩条在重力荷载和风荷载作用下的受力性能进行了有限元分析,分析时将蒙皮体系对檩条的约束作用采用两个弹簧：一个侧向弹簧和一个扭转弹簧来代替,对其静力性能进行了分析。     

蒙皮支撑C型截面檩条的静力性能分析

将蒙皮体系对檩条的约束作用简化为一个侧向弹簧和一个扭转弹簧,并将此模型用ANSYS进行分析,分别考虑侧向弹簧和扭转弹簧对檩条的蒙皮作用,并对其静力性能进行了分析。     

蒙皮支撑压弯构件性能的简化有限元分析方法

本文在已有的蒙皮支撑压弯构件几何非线笥有限元分析理论和试验研究的基础上作出若干基本假定,一种蒙皮支撑压弯构件的简化有限元分析模型。     

蒙皮效应对铝合金单层网壳结构性能的影响

为研究蒙皮效应对铝合金单层网壳结构性能的影响,运用有限元软件的参数化建模建立系列结构模型,对网壳结构进行静力分析与非线性稳定分析,考察蒙皮效应对网壳静力性能及非线性稳定极限承载力的影响。结果表明:蒙皮效应可以降低绝大部分杆件的轴应力与弯曲应力;考虑蒙皮一般可以提高网壳的稳定极限承载力,提高幅度随着矢跨比的增大而增大,随着跨度的增加而减小,但也出现个别网壳承载力反而降低的情况,为安全起见,建议在单层网壳静力分析与整体稳定分析中考虑蒙皮的作用。     

考虑蒙皮和节点刚度的铝合金网壳稳定性

为明确蒙皮效应和节点半刚性对铝合金单层球面网壳静力稳定性的影响,运用有限元软件建立了一个125 m跨度的结构模型。首先通过数值模拟确定了初始缺陷和材料非线性对网壳稳定性能的影响,并在此基础上考虑蒙皮效应和节点半刚性进行对比分析。分析结果表明:蒙皮效应可以显著提高铝合金单层网壳静力稳定承载力,并改变结构屈曲模态,考虑节点半刚性会大幅降低网壳极限承载力,当同时考虑蒙皮和节点刚度时,该网壳稳定性能基本不变。     

金属蒙皮支撑C形檩条的计算理论

归纳了开口冷弯薄壁截面的几何特征和薄壁杆件的受力性能、特征,对蒙皮支撑C形檩条的抗剪刚度和抗扭刚度进行了分析,研究蒙皮支撑C形檩条在风吸力作用下的基本性能,旨在更深入了解金属蒙皮支撑檩条在整体蒙皮结构中所起的作用。     

Seismic performance of Y‐type eccentrically braced frames combined with high‐strength steel based on performance‐based seismic design

In the Y‐type eccentrically braced frame structures, the links as fuses are generally located outside the beams; the links can be easily repairable or replaceable after earthquake without obvious damage in the slab and beam. The non‐dissipative member (beams, braces, and columns) in the Y‐type eccentrically braced frames are overestimated designed to ensure adequate plastic deformation of links with dissipating sufficient energy. However, the traditionally code design not only wastes steel but also limits the application of eccentrically braced frames. In this paper, Y‐type eccentrically braced steel frames with high‐strength steel is proposed; links and braces are fabricated with Q345 steel (the nominal yield stress is 345 MPa); the beams and columns are fabricated with high‐strength steel. The usage of high‐strength steel effectively decreases the cross sections of structural members as well as reduces the construction cost. The performance‐based seismic design of eccentrically braced frames was proposed to achieve the ideal failure mode and the same objective. Based on this method, four groups Y‐type eccentrically braced frames of 5‐story, 10‐story, 15‐story, and 20‐story models with ideal failure modes were designed, and each group includes Y‐type eccentrically braced frames with ordinary steel and Y‐type eccentrically braced frames with high‐strength steel. Nonlinear pushover and nonlinear dynamic analyses were performed on all prototypes, and the near‐fault and far‐fault ground motions are considered. The bearing capacity, lateral stiffness, story drift, link rotations, and failure modes were compared. The results indicated that Y‐type eccentrically braced frames with high‐strength steel have a similar bearing capacity to ordinary steel; however, the lateral stiffness of Y‐type eccentrically braced frames with high‐strength steel is smaller. Similar failure modes and story drift distribution of the prototype structures designed using the performance‐based seismic design method are performed under rare earthquake conditions.     

Elastic buckling load of multi-story frames consisting of Timoshenko members

The objective of this paper is to propose a method for the evaluation of the elastic critical buckling load of columns in frames consisting of members susceptible to non-negligible shear deformations, such as built-up members in steel frames, based on Engesser's approach. To that effect, a stability matrix is proposed and three general stability equations are derived for the cases of unbraced, partially braced and braced frames. Indicative graphic interpretation of the solutions for the stability equations of the braced and unbraced cases is shown. Slope-deflection equations for shear-weak members with semi-rigid connections are also derived and used for the presentation of a complete set of rotational stiffness coefficients, which are then used for the replacement of members converging at the bottom and top ends of the column in question by equivalent springs. All possible rotational and translational boundary conditions at the far end of these members, as well as the eventual presence of axial force, are considered. Five examples are presented, dealing with braced, unbraced and partially braced frames, with rigid and semi-rigid beam to column connections, loaded with concentrated or uniformly distributed loads, in a symmetrical or non-symmetrical pattern. In all cases the proposed approach is in excellent agreement with finite element results.     

基于OpenSEES数值模拟的工字形截面支撑低周疲劳性能研究

为研究工字形截面支撑低周疲劳性能,进行了18根Q235和21根ST12材质焊接工字形钢支撑在等幅轴向循环位移作用下的OpenSEES有限元分析,在验证模拟结果和试验结果吻合较好的同时,提出利用支撑几何参数(长细比、宽厚比、高厚比、屈服点)修正的表征应变作为预测支撑低周疲劳寿命的控制参量,给出了对应修正公式和寿命预测公式。表征应变与支撑低周疲劳寿命满足对数线性关系,据此预测的支撑低周疲劳寿命离散性较小且基本位于试验值1.5倍分散带内。对于变幅加载条件下的支撑寿命预测,利用Miner线性损伤理论对39组支撑试验数据进行以裂纹萌生寿命为终止点的损伤值统计,给出了容许损伤建议值作为预测寿命对应损伤值。而后,引入5组单斜工字钢支撑框架低周疲劳试验结果进行验证,其预测寿命均接近试验裂纹萌生寿命,可以较为保守地评估该类支撑的低周疲劳寿命,且支撑截面损伤分布与试验破坏模式保持一致。以上均证明该数值模拟方法和低周疲劳寿命预测方法的准确性和高效性,可为框架支撑结构低周疲劳性能的研究提供借鉴。     

隅撑支撑钢框架的抗震性能分析

为研究隅撑支撑钢框架结构的抗震性能,对纯框架（MRF）、中心支撑框架（CBF）、偏心支撑框架（EBF）和隅撑支撑框架（KBF）等主要框架结构形式的内力进行分析并进行有限元分析对比。结果表明：隅撑支撑钢框架结构的受力性能与耗能能力都要比其他类型的框架形式要好。在相同条件下,KBF比其他形式的框架结构具有更好的抗震性能,因此隅撑支撑钢框架结构是一种良好的结构形式。     

Two-stage damage diagnosis approach for steel braced space frame structures

In order to diagnose the location and extent of damage in steel braced space frame structures, a two-stage damage diagnosis approach is proposed. This approach is comprised of the damage locating vectors method and eigensensitivity analysis. By deriving formulas used to calculate characterizing stresses in space frame members, and by defining characterizing stresses in connections, the damage locating vectors method is extended to locate damage in space frame members and connections. In addition, the simplified calculation of modal mass-normalization constants for damaged structures is improved. The first- and second-order sensitivities of the modal parameter discrepancies with respect to the structural model parameters and the stiffness matrix of beam elements with one damaged end are utilized. To verify the effectiveness of the proposed approach, numerical simulation analysis and experimental testing of a steel braced space frame model are performed. Ten and seven damage patterns are simulated in the numerical example and experimental testing, respectively. Modal parameters of the undamaged and damaged structures are extracted from the acceleration data using the natural excitation technique (NExT) and the eigensystem realization algorithm (ERA). The extended damage locating vectors method is utilized to determine potentially damaged elements. Based on the identified modal information, the extent of damage of the potentially damaged elements is estimated using the second-order eigensensitivity analysis. It is demonstrated that the two-stage damage diagnosis approach is effective when the damage of the members or connections in steel braced space frame structures reaches a certain level.     

Progressive collapse analysis of seismically designed steel braced frames

The progressive collapse resistance of seismically designed steel braced frames is investigated using validated computational simulation models. Two types of braced systems are considered: namely, special concentrically braced frames and eccentrically braced frames. The study is conducted on previously designed 10-story prototype buildings by applying the alternate path method. In this methodology, critical columns and adjacent braces, if present, are instantaneously removed from an analysis model and the ability of the model to successfully absorb member loss is investigated. Member removal in this manner is intended to represent a situation where an extreme event or abnormal load destroys the member. The simulation results show that while both systems benefit from placement of the seismically designed frames on the perimeter of the building, the eccentrically braced frame is less vulnerable to progressive collapse than the special concentrically braced frame. Improvement in behavior is due to improved system and member layouts in the former compared to the latter rather than the use of more stringent seismic detailing.     

Y型偏心支撑钢框架在循环荷载作用下的滞回性能分析

Y型偏心支撑钢框架是一种偏心抗震耗能的结构形式。采用曲壳单元和梁单元相结合的非线性有限元分析模型,自编计算程序,分析了Y型偏心支撑钢框架在循环荷载作用下的滞回性能,提出了相应的抗震设计对策和建议。     

D型偏心支撑钢框架耗能梁段性能研究

通过对具有不同耗能梁段长度的D型偏心支撑钢框架的滞回性能及耗能梁段耗能性能的非线性有限元分析,表明耗能梁段的长度对偏心支撑钢框架的侧向刚度、延性和耗能能力有较大影响。随着耗能梁段长度的增加,D型偏心支撑钢框架的强度、刚度、延性和耗能性能均产生了不同程度的退减现象;耗能梁段越短,其塑性变形越大,进而导致耗能梁段过早塑性破坏的可能性增大。根据有限元模拟结果提出了对耗能梁段长度的设计建议。     

弹性支承单层柱面网壳稳定性

本运用非线性有限元全过程分析方法，结合新建的成都双流机场候机楼屋面大跨度单层柱面网壳，对弹性支承的大跨度单层柱面网壳结构的稳定性进行了分析，对比了不同支承条件、不同矢跨比和不同杆件截面对弹性支承的单层柱面网壳稳定性的影响，得出了有实际应用价值的结论。