钢结构门式刚架厂房抗风性能和极限承载力分析

为研究不同钢结构门式框架厂房的抗风特性,以长汀县高性能纳米钛酸钡产业化项目为研究背景,运用数值有限元模拟的方法建立门式刚架厂房计算模型,研究了不同节点刚度下门式刚架的风致动力响应及不同风荷载强度的弯矩变化规律。研究结果表明,随着门式刚架厂房节点刚度的降低,钢柱顶点的最大位移和位移平均值均不断增加,而卓越响应频率则不断降低;不存在风荷载作用的门式刚架厂房弯矩图呈正对称,而存在风荷载作用的门式刚架厂房弯矩图呈反对称,后者的最大弯矩比前者增加3～5倍,表明风荷载对刚架的受力起到了控制作用,对于刚架的极限承载力具有显著的影响。相比于刚架柱脚和梁柱节点,刚架顶部节点的最大正负弯矩值均较小,而前者的最大正负弯矩值随风速的增加而不断增加,在门式刚架厂房抗风设计中可以通过加大柱截面、提高柱体脚部的刚度、将柱脚嵌固边界改为铰接边界、梁柱节点增加腋角等方式提高结构的抗风能力。     

冷弯型钢檩条设计应注意的问题

檩条在轻钢结构屋面上承担着梁的功能和支撑的作用,其用钢量在门式刚架轻钢结构系统中居第二位,故应对檩条设计予以足够的重视。1荷载1·1雪荷载屋面雪荷载根据屋面形式不同而不同。檩条按积雪不均匀分布的最不利情况采用,不应将全部檩条都取雪荷载的平均值。1·2风荷载规范、规程对风荷载标准值的计算公式不同。垂直于建筑物表面的风荷载标准值应按《门式刚架轻型房屋钢结构技术规程》(CECS102:2002)附录A中表A·0·2-2檩条和墙梁的风荷载体型系数计算。不符合A·0·2条件的门式刚架轻型房屋或其他类型房屋按《建筑结构荷载规范》(GB50…     

女儿墙对轻型门式刚架结构内力的影响分析

女儿墙是门式刚架轻型房屋钢结构的屋面围护结构,对风荷载较为敏感并在一定程度上会影响屋面积雪荷载的分布,因此需要研究女儿墙对结构内力的影响。本文分析了有女儿墙与无女儿墙轻型门式刚架结构在不同风荷载和雪荷载作用下结构的内力变化情况,并对比了分析结果,得出工程结构设计中不应忽视女儿墙的影响,应根据实际情况进行结构内力分析计算。     

门式刚架屋面坡度对二阶效应的影响及二阶弯矩计算公式

采用有限元法较精确地分析了门式刚架在荷载作用下的二阶效应随屋面坡度变化的规律。分析中计及轴力、轴向变形、剪切变形的影响 ,提出了单跨双坡门式刚架的二阶弯矩近似计算公式 ,其结果可供设计人员参考     

结构力学中反对称荷载作用下对称刚架的弯矩图规律

在结构力学的学习过程中,绘制弯矩图是基本功,属于重点考查内容,也是结构内力分析的起始性关键环节。超静定结构的弯矩图比较复杂,严重影响了学生对基本内容的理解和掌握。文章旨在通过对比静定对称刚架的弯矩图,分析反对称荷载作用下超静定对称刚架的弯矩图特点,从而找出对称刚架弯矩图的一般性规律。     

全局布索预应力刚架体系研究

在现有门式刚架和预应力技术研究的基础上,提出全局布索预应力刚架体系,该结构相比索支承刚架增设了预应力隅撑系统。采用数值分析方法研究了全局布索预应力刚架体系在各种工况作用下的工作机理,并与门式刚架、索支承刚架的受力性能进行了对比研究。研究表明,索支部分对刚架在竖向荷载下的受力、变形性能影响较大,隅撑部分能有效改善刚架在风荷载作用下的受力和变形性能,并在一定程度上提高结构抗侧能力,因此全局布索预应力刚架体系适用于风荷载占较大比例的情况。     

利用增量法分析门式刚架的抗灾害能力

利用荷载增量法分析了门式刚架在水平荷载作用下的受力状况,得到刚架在破坏时的极限荷载以及塑性铰出现的先后顺序和出现塑性铰时与之对应的荷载值,通过采取一定措施对节点域进行加强,采取在出现塑性铰的节点域加腋的方式来提高节点的承载力,经计算节点承载力大为提高,使结构具有更大的安全储备,从而使结构具有一定的抵抗超越荷载的抗灾害能力。     

不同规范中雪荷载作用下门式刚架静力响应和稳定性研究

对ISO、中、美、加、欧规范中门式刚架屋盖结构受到雪荷载作用时的响应进行比较。运用有限元软件ANSYS,对不同坡度的变截面门式刚架在5种规范不同积雪分布形式下的静力响应进行分析,并计算考虑不同初始缺陷幅值的结构整体稳定临界荷载因子,总结雪荷载作用下门式刚架的失稳特点。分析结果表明:门式刚架的基底剪力、跨中竖向位移、临界荷载因子与雪荷载总量密切相关;各规范下非均匀雪荷载较均匀雪荷载作用下柱顶水平位移大;结构稳定性随初始缺陷幅值增大而降低,随屋面坡度增大而增大,对缺陷不敏感;非均匀雪荷载更容易使结构发生有侧移失稳。     

双坡轻钢结构门式刚架的内力计算

目前,轻钢结构厂房最常见的结构形式为双坡门式刚架。轻钢结构门式刚架自重较轻,受屋面活荷载的影响较大,在内力计算时通常由屋面活荷载所控制。屋面活荷载包括不上人屋面活荷载(即屋面施工及检修荷载)和屋面雪荷载,有时还会有屋面积灰荷载。通过分析荷载规范对不上人屋面活荷载和屋面雪荷载的相关规定,提出了一种双坡轻钢结构门式刚架的内力计算方法,即兼顾屋面雪荷载全跨均匀布置的效应和不上人屋面活荷载全跨不均匀布置的效应,取其最不利效应进行构件截面设计的方法。     

开敞式房屋风荷载的计算

结合门式刚架轻型房屋钢结构特点,以具体项目为例,介绍了美国MBMA86中关于开敞式房屋风荷载的计算方法,包括刚架、屋面檩条、屋面板等不同部位的风荷载计算,以指导国内设计人员更好地使用门式刚架轻型房屋钢结构技术规程。     

An efficient method for computation of effective length factor of columns in a steel gabled frame with tapered members

The concept of effective length is the only available common method for column design without non-linear structural analysis. Researches conducted for determination of effective length of members are mainly related to a constant moment of inertia. In many investigations related to members with variable moment of inertia, finite element and approximation methods are used. In this article, a method for quick calculation of the effective length factor of columns in steel gabled frames with tapered members is proposed. The method is based on two-dimensionless design-oriented charts relating the critical load of columns to frame characteristics and boundary conditions. Since I-sections are usually used for gabled frames members, the variation of moment of inertia along the length of members (beams or columns) is approximated as a parabolic function. As is demonstrated in the Numerical studies, these calculations can yield, in a very efficient way, accurate results for gabled frames consisting of tapered elements.     

轻型门式刚架钢结构荷载取值审查常见问题剖析

本文对轻型门式刚架钢结构设计中常见的荷载问题进行了归纳整理,分析了恒载、活载、风载、雪载及吊车荷载取值对主次结构的影响,强调设计人员应重视与荷载有关的参数取值及荷载简图的复核,可供设计和审查人员参考。     

轻型门式刚架风灾破坏形式及其工程措施

轻型门式刚架作为一种常用的结构形式,已被广泛应用于工业建筑中。但由于轻型门式刚架对风荷载非常敏感,为提高其抗风能力,减少风灾损失,针对以往台风灾害中轻型门式刚架的破坏形式及其原因进行分析,总结经验教训,提出了相应的工程措施,可为轻型门式刚架抗风设计提供参考。     

轻型钢结构门式刚架在GMP厂房中的应用

为了保持洁净厂房的气密性,从建筑结构设计角度,结合GMP厂房的施工构造做法,提出合理的结构布置方案。通过对门式刚架结构在风荷载作用下的柱顶位移进行参数分析,提出用于GMP厂房的门式刚架结构的位移限值不大于厂房结构高度1/240的建议取值,可供类似工程的洁净车间施工及结构设计参考。     

Effect of relative intensity of wind load on the RC column reliability in tall buildings

Wind loads are very important in the design of tall buildings as often the load combinations containing the wind load govern the design. As for reliability, however, because of the higher inherent uncertainty in the wind load in comparison to the gravity load, safety indices decrease as the ratio of wind load to gravity load increases. The safety indices in RC columns depend on the nominal wind to gravity load ratios. Due to the interaction between bending moment and axial force, a single ratio cannot be defined, because the eccentricity is not similar for wind and gravity loads. In this paper, the ratio of wind to gravity loads is considered separately for axial force and bending moments. Unlike conventional approach, here it is assumed that the wind and gravity loads' eccentricities are not equal, and the final load eccentricity used in either the design or the reliability analysis is a function of applied loads. The results demonstrate that the sensitivity of RC columns' safety indices to bending moment ratios is higher than that of axial force ratios. Furthermore, the variation of RC columns' safety indices with a low rebar percentage is very different from RC columns with high rebar percentages. Copyright © 2010 John Wiley & Sons, Ltd.     

Second-Order Elastic-Plastic Analysis of Multistory Building Frames by Marching Technique

In two previous papers, second-order elastic analysis of multistory building frames by marching technique [1] and elastic-plastic analysis of rectangular frames [2] have been dealt with. The algorithms described in those two papers are now combined into an efficient computer program for conducting the elastic-plastic analysis of multistory building frames by marching technique. With this program, the response of a multistory building frame, subjected to uniform loads on the beams and lateral loads at the floor levels, may be traced from the service load condition to proportionate overloads until collapse through sequence of formation of plastic hinges. Because & am spans are not divided into elements in the analysis, plastic hinges are assumed to remain at the same locations once they are installed on them. Consequently, moments in beams may later exceed slightly the plastic moment capacity. It is believed that the algorithm is useful to form a basis for further investigations, such as considerations for more than the two essential second-order effects, or for effects of semirigid beam-to-column connections and of axial force on the plastic moment capacity.     

多层住宅新型复合结构体系的结构选型分析

对由截面较小的梁、柱、支撑形成的复合结构代替住宅中承重墙的新型住宅结构体系进行了结构选型分析。选取常见的三种支撑形式 ,用不同软件分别对其进行了竖向荷载和水平风荷载作用下的内力计算分析。其结果表明 ,竖向荷载作用下 ,“人字”支撑的结构体系内力最小 ,构件弯矩、剪力仅为另两种形式的 2 0 %～ 6 0 % ;水平荷载作用下 ,三种支撑结构的内力相差较小 ,说明三种支撑结构体系在抗侧能力方面基本相等 ,但和框架结构内力相比 ,梁的弯矩仅为框架梁的 1 5 0 ,柱弯矩仅为 1 2 5。由此得出“人字”支撑结构为新型复合结构体系较合理的结构形式。     

成都双流国际机场货运站区结构设计

介绍了机场货运站大跨度门式刚架的设计情况,对荷载取值、主要计算控制参数的取值、节点计算方法及节点设计、库区地面处理提出了一些建议。为大跨度门式刚架设计提供参考。     

钢框架延性节点塑性铰外移的机理研究

在钢结构框架节点的延性和抗震性能的设计中,多种不同削弱形式的梁均能够实现在水平荷载作用下节点塑性铰外移的目的.为此,重点从结构的受力方面,采用增量变刚度法对节点塑性铰外移的机理进行相关研究.对削弱型节点连接类型及传统型的节点连接类型进行相关的结构受力机理的推导研究,从理论上分析比较不同框架结构模型在水平荷载作用下的破坏模式及所对应的极限荷载.综合比较得出：采取一定的削弱方式能够改变构件的极限弯矩,进而实现塑性铰外移的目的;采取合理的削弱形式能够保证在结构极限荷载降低不明显的情况下实现塑性铰外移的目的.     

New method of inelastic buckling analysis for steel frames

In general, the concept of bifurcation stability cannot be used to evaluate the critical load of typical steel frames that have geometric imperfections and primary bending moment due to transverse loads. These cases require a plastic zone or plastic hinge analysis based on the concept of limit-load stability instead. However, such analyses require large computation times and complicated theories that are unsuitable for practical designs. The present paper proposes a new method of inelastic buckling analysis in order to determine the critical load of steel frames. This inelastic analysis is based on the concept of modified bifurcation stability using a tangent modulus approach and the column strength curve. Criteria for an iterative eigenvalue analysis are proposed in order to consider the primary bending moment as well as the axial force by using the interaction equation for beam-column members. The validity and applicability of the proposed inelastic buckling analysis were evaluated alongside elastic buckling analysis and refined plastic hinge analysis. Simple columns with geometric imperfections and a four-story plane frame were analyzed as benchmark problems. The results show that the proposed inelastic buckling analysis suitably evaluates the critical load and failure modes of steel frames, and can be a good alternative for the evaluation of critical load in the design of steel frames.