等截面门式刚架塑性设计方法的讨论

将我国等截面门式刚架塑性设计方法与英国门式刚架的设计方法进行了比较和讨论 ,内容包括应用情况、内力计算、强度计算、塑性设计应满足的条件和整体稳定的计算方法等。通过比较和分析 ,对今后我国等截面门式刚架塑性设计方面进一步研究和发展提出了建议。     

轻型钢结构刚架的塑性分析

本文对不等高多跨双坡门式刚架,提出了可用平横梁门式刚架按机动法求得塑性铰位置,再按静力平衡法确定弯矩值的方法,并论证其可行性,可使多跨双坡门式刚架计算简化和实用。     

塑性设计在轻钢门式刚架中的应用

本文阐述了钢结构塑性设计的基本原理,介绍了求解极限荷载的静力法和机动法,应用机动法进行轻钢门式刚架的塑性设计是很合适的。本文特以工程实例作了具体应用分析。     

受竖直向上荷载作用的门式刚架塑性分析

门式刚架多用轻型屋面,在沿海等强风地区屋面风吸力可成为向上的荷载,一般刚架塑性弯矩计算公式或图表求解刚架内力已不能适用,如何考虑特定风荷载作用下结构的受力与变形是刚架设计施工中必须解决的实际问题。根据结构塑性分析的机动法原理,提出在向上荷载作用下无加腋单跨刚架塑性弯矩的算法。     

横梁均布荷载下单层无侧移刚架稳定承载力研究

为考虑横梁荷载下单层无侧移刚架的稳定承载力,首先采用转角位移法对横梁荷载下刚架稳定承载力进行分析,明确柱顶作用集中荷载与横梁作用均布荷载下的刚架稳定承载力相差很大。对横梁均布荷载下无侧移刚架的实用计算方法进行阐述,刚架需区分弱梁与弱柱刚架,前者采用梁柱易位法,后者采用传统的标准法确定柱计算长度系数。比较考虑二阶效应与实用计算方法所得柱计算长度系数,计算结果表明,考虑二阶效应将使柱计算长度系数偏于保守,横梁轴压力宜采用一阶分析。其次,采用有限元软件Abaqus分析两种典型无侧移刚架的屈曲性能,验证实用计算方法的正确性。最后,设计了96组算例对刚架类型的实用判别公式进行分析计算,并与有限元分析结果进行对比,验证了实用判别公式的正确性。     

刚架结构极限承载力可靠性分析

本文根据塑性极限分析的基本原理,利用塑性极限分析的上、下限定理(静力法和机动法)确定刚架结构的塑性极限承载能力,进而由塑性极限荷载和外荷载建立了极限承载能力的极限状态方程,对刚架结构进行了可靠性分析,并与传统的计算方法进行对比.     

刚架结构极限承载力分析的广义塑性铰研究

传统塑性铰法及其改进方法具备比例特点,能够根据外荷载与内力之间的比例关系快捷确定刚架的塑性铰位置和极限承载力,但不能应用于多内力组合作用下的刚架极限承载力问题。随后发展起来的二阶塑性铰法和精细塑性铰法尽管解决了该问题,但不具备比例特点,需通过大量迭代试算、并连续调整荷载增量来确定刚架的塑性铰位置和极限承载力,导致理论复杂,计算效率低。为此,文章利用广义屈服准则提出内力组合因子的定义,据此建立具备比例特点的广义塑性铰法,能够快捷处理刚架结构在多内力组合作用下的极限承载力问题。首先,利用广义屈服准则研究建立内力组合因子,据此修正刚架单元在不同加载步的截面强度。然后,利用齐次广义屈服函数和标准化内力定义单元承载比,并根据荷载与单元承载比之间的比例关系快捷确定各加载步的塑性铰位置和极限承载力。最后,通过与弹塑性增量法和改进塑性铰法对比分析,验证了该方法具有简捷、高效和高精度特性。     

基于整体承载极限状态的钢结构可靠度设计方法及其在门式钢刚架设计中的应用

本文提出了基于整体承载极限状态的钢结构可靠度设计思路。这种思路建立在钢结构整体非线性分析和验算的基础上,并确保结构整体而非构件的可靠度水平,使结构整体的实际可靠度水平尽可能地接近于设计的目标值。本文针对门式钢刚架结构建立了一套实现这种设计的方法,包括结构整体非线性分析、结构体系可靠度计算以及实用的设计表达式。通过三个门式钢刚架结构设计实例比较了传统的构件设计方法,不考虑体系可靠度的整体承载极限状态设计方法和本文考虑体系可靠度的整体承载极限状态设计方法的设计结果,说明本文所提出设计思想的先进性。     

轻型门式刚架结构设计中几个问题的探讨

轻型门式刚架结构在我国得到了广泛应用,工程实践中遇到一些国家标准规范尚未完善或不明确的问题。本文对门式刚架的适用范围、摇摆柱的应用、屋盖纵向水平支撑的设置、冷弯薄壁型钢檩条的设计计算中遇到的几个问题进行探讨,以期为门式刚架的设计提供一些实用经验。     

等截面斜腿刚架平面内整体稳定性能研究

用ANSYS有限元程序,考虑几何非线性,对等截面斜腿刚架进行了大量的荷载-位移全过程分析。分析中考虑了柱倾斜角度、柱高度与跨度比和梁的起拱坡度等参数,以及梁上均布荷载和集中力两种加载形式,最后给出了斜腿刚架的各种失稳模式和相应刚架柱的计算长度系数,供设计时参考。二阶弹塑性算例分析表明,在利用有效长度法进行斜腿刚架平面内整体稳定性验算时,除刚架柱外,还要验算梁的稳定性。     

Drift design of steel‐frame shear‐wall systems for tall buildings

Drift design methods based on resizing algorithms are presented to control lateral displacements of steel‐frame shear‐wall systems for tall buildings. Three algorithms for resizing of structural members of the steel‐frame shear‐wall systems are derived by formulating the drift design process into an optimization problem that minimizes lateral displacement of the system without changing the weight of a structure. During the drift design process, cost‐effective displacement participation factors obtained by the energy method are used to determine the amount of material to be modified instead of calculating sensitivity coefficients. The overall structural design model with the drift design method for the steel‐frame shear‐wall systems is proposed and applied to the structural design of three examples. As demonstrated in the examples, the lateral displacement and interstorey drift of a frame shear‐wall system can be effectively designed by the drift design method without the time‐consuming trial‐and‐error process. Copyright © 2002 John Wiley & Sons, Ltd.     

框架-核心筒结构的框架内力调整方法对比研究

在框架-核心筒结构的抗震设计中,作为二道防线的外框架部分,需要对其内力进行调整,但我国相关标准在调整方法和调整要求上存在差别,使得设计具有一定程度的不确定性。基于对我国JGJ 3-2010、CECS 230:2008和美国IBC 2000等标准规定的分析和解读,分别从适用范围、调整对象、双重抗侧力体系划分、框架合理刚度、内力重分布等5个方面,对比分析基于基底剪力或最大框架楼层剪力调整方法和基于楼层剪力调整方法的不同。以一实际结构为例,通过弹塑性分析和振动台试验研究了不同调整方法对各部分设计的影响。结果表明：可采用外框架和核心筒承担的剪力比例或者整体刚度分析方法来界定其是否为双重抗侧力体系;外框架与核心筒互为二道防线,在设计时,需对其承载力和刚度协调匹配,对承载力可采用基于楼层剪力的调整方法,调整对象除剪力和弯矩外也应包括轴力,两者的最小分担比例之和为100%,框架最小和最大分担比例分别为20%和80%,对于两者间的刚度匹配关系,可采用广义刚度特征值和刚度比参数来评价,其合理取值范围分别为1~3和0.2~0.9。     

钢框架结构基于整体优化策略的非线性抗震设计

针对现有抗震优化设计很少考虑结构非线性反应的缺点,提出了整体优化策略,并运用到钢框架结构造价最小的抗震优化设计中。以结构构件截面尺寸为设计变量,结构构件的总体积为目标函数,整体优化策略在以结构弹性强度和弹性变形为约束条件的基础上,增加弹塑性变形为约束条件,与我国抗震设计规范两阶段设计方法相对应,因此基于整体优化策略的优化设计结果可以作为最终的结构设计方案。整体优化策略不仅能够考虑结构的非线性反应,而且可以采用我国抗震规范的相关规定作为约束条件,适用于钢框架结构造价最小的抗震优化设计。     

A practical design method for semi-rigid composite frames under vertical loads

Although the benefits of semi-rigid connections and composite actions of slabs are extensively documented in the design of steel frames, they are not widely used in practice. The primary cause is the lack of appropriate practical design methods. In this paper, a practical method suitable for the design of semi-rigid composite frames under vertical loads is proposed. The proposed method provides the design of the connections, beams and columns for semi-rigid composite frames at the ultimate and serviceability limit states. The rotational stiffness of beam-to-column connections for calculating the deflection of the frame beams and the effective length factor of columns are also determined. In addition, the accuracy of the proposed design method is verified by a pair of tests carried out on full-scale semi-rigid composite frames. Moreover, a design example is proposed to demonstrate the application of the proposed design method. It is shown that the proposed design method not only takes into account the actual behavior of the beam-to-column connections and its influence on the behavior of the overall structures, but is also simple and convenient for a designer to use in engineering practice.     

框架结构整体承载力优化设计的改进方法

为解决框架结构整体承载力优化设计方面存在的问题,建立了多内力组合下矩形和工字形截面几何参数的调整方法,并通过引入强化迭代系数提出了框架结构整体承载力优化设计的改进方法。首先,通过弹性模量缩减法分析框架结构在组合内力下的损伤演化过程,据此确定框架结构在构件和整体2个层面的承载力需求。然后提出了强化迭代系数并确定了其取值,据此调整构件截面强度,建立了结构整体承载力优化设计的加速迭代格式,其可保证框架结构在构件和整体2个层面上的安全性需求并优化结构耗材。同时,为实现截面强度调整在结构计算模型中的更新,建立了多内力组合作用下矩形和工字形截面几何参数调整公式,可根据截面强度调整需求进行截面几何参数的调整。最后,通过与满应力优化准则法对比分析验证了所提方法的合理性。结果表明:采用构件截面几何参数调整方法和加速迭代格式,强化迭代系数取1.001～1.020时,所提方法迭代收敛速度快,且能够获得承载性能和经济性能均优的框架优化设计方案。     

Efficient semi-analytical generator of initial stiffness designs for steel frames under seismic loading. Part 1: Fundamental frame

The purpose of this paper is to propose a new efficient semi-analytical generator of initial stiffness designs for a moment-resisting steel building frame under seismic loading. Requirements on interstory drift under seismic loading are often active constraints in the usual structural design practice for steel building frames and simple methods of design and analysis are needed especially in the preliminary design stage. Interstory drifts and ratios of the angles of nodal rotation to the angles of column member rotation are selected as key parameters and specified based upon the designer's intention. A practical design formula for a frame with design variable grouping is proposed as well as one for a basic frame without design variable grouping. A recursive technique is introduced to evaluate the design story shear forces under a set of design-spectrum-compatible earthquakes. Numerical examples are presented to disclose the characteristics of member stiffness distributions and the response characteristics of frames designed by the present method. In the present paper (Part 1), a fundamental design formula is proposed for a simple frame without column elongation. A more practical design formula for a slender frame with column elongation will be presented in the companion paper. (Part 2). © 1997 John Wiley & Sons, Ltd.     

水平荷载作用下半刚性连接组合梁钢框架设计

在总结国内外研究的基础上,结合我国有关刚接框架的设计方法及钢结构设计规范,给出了半刚性连接组合梁框架在水平荷载作用下的简化设计流程及方法,并通过设计算例说明本文推荐的简化设计方法简便易行,同时通过对不同类型框架的经济性比较,说明半刚性连接组合梁框架结构具有较好的经济性及应用前景。     

整体式矩形阳台结构内力计算

整体式矩形阳台结构内力按传统方法计算存在一定的不安全因素，本文用能量原理推导出求解水平刚架内力的一般方法，按此方法计算矩形阳台挑梁与边梁的内力较为接近实际，可供结构设计参考。     

Machine Learning User Preferences for Structural Design

Abstract: The design process often proceeds through iterative stages of design configuration, analysis, evaluation, and redesign with the ultimate goal of optimization. Numerical methods for structural design optimization of only one attribute such as weight, strength, or cost are well known. However, these methods do not reflect the fact that designs are evaluated by the user in terms of their performance in several attributes. It has been extremely difficult to incorporate multiple attributes into design optimization algorithms because the acceptable tradeoffs between these attributes vary significantly between users.
This paper presents a new method for learning user-specific preferences and integrating them into the design evaluation, analysis, and optimization process in a meaningful way. The approach is a synthesis of formal decision theoretic methods with conventional design analysis techniques. The overall design objective is optimization of multiattribute utility from the viewpoint of the user.
A user-interactive computer-aided Multiattribute Structural Design Evaluation and Optimization System (MSDEOS) is presented. It enables machine learning of the user's willingness to make tradeoffs between performance attributes. With this system, it is feasible to integrate site-specific consideration of multiple attributes directly into computer aids for structural design optimization. Two examples are presented: seismic design, where tradeoffs are made between cost and damage index, and design of a three-story steel frame structure, where attributes are cost and drift index. The system learns the preferences of different users and reflects those preferences through the identification of a different optimal solution for each user.