加强环式钢管混凝土框架节点计算模型的研究

在分析加强环式连接的钢管混凝土框架时,一般采用刚性框架分析法,把节点假设为完全的刚性连接。然而这种假设并不符合实际。通过两层两跨的框架静载试验,研究了节点核心区的剪切变形,并测量了框架的水平荷载-侧移曲线,以验证本文的节点计算模型的准确性。试验发现弹性阶段节点核心区的剪切刚度很大,对框架变形的影响可以忽略不计。借助有限元分析软件ANSYS建立框架有限元模型,采用了一种新的节点计算模型,即用弹簧单元和刚性单元来分别模拟梁柱连接和节点核心区,弹簧刚度由文献[6]的M-θ公式确定。将本文方法及其它分析方法得到的水平荷载-侧移曲线与框架试验结果进行比较,证明了本文的方法比传统的刚性框架分析法及其它方法,更加准确地反映了框架弹性阶段的受力性能。     

竖向支撑对延性节点钢框架抗侧移能力的影响

首先比较分析了狗骨式和普通式节点钢框架的抗侧移情况,其次考虑了四种布置模式竖向支撑并着重对狗骨式节点钢框架进行了Etabs有限元分析,通过比较各种计算分析结果,提出强化狗骨式节点钢框架抗侧移能力的措施。     

半刚接钢框架柱稳定承载力研究

通过引入线刚度修正系数来考虑连接的非线性,采用变刚度螺旋弹簧单元模拟半刚性节点的特性,给出了考虑连接节点刚度影响的无侧移、有侧移钢框架柱的计算长度系数公式,讨论了半刚性连接对框架稳定承载力的影响。研究结果表明:节点刚度对纯框架柱计算长度系数有显著的影响。在无侧移情况下,有限元分析结果与理论计算值吻合较好;在有侧移情况下,节点连接的有效刚度与作用在框架梁上的荷载大小及形式等有关,准确确定有效刚度比较复杂,理论计算与有限元分析结果相差较大,理论解偏于保守。     

基于ABAQUS二次开发的RC框架结构屈服机制

为了研究水平荷载作用下钢筋混凝土现浇楼板对框架结构屈服机制的影响,首先验证了适用于ABAQUS非线性纤维梁单元用户材料子程序的准确性,在此基础上,建立带有楼板及其钢筋的框架模型和空框架模型,分析结构变形方式、各榀框架节点梁柱内力分配以及节点受拉区板筋的参与工作范围。研究表明,现浇楼板影响空间框架结构"强柱弱梁"屈服机制的实现;框架节点受拉区板筋内力和参与工作范围随着框架侧移的增加而增大;梁端受拉区的有效翼缘宽度取梁侧6倍板厚并不全面,应结合不同侧移和设防烈度进行全面分析。     

柔性连接的弱支撑框架结构的稳定性

本文对于设置了支撑的框架结构，并且节点是柔性连接时的稳定性问题进行了研究。同时给出了在此种条件下的阈值刚度和柱子的计算长度系数的表达形式。这样可以更加合理地区分有侧移和无侧移框架。通过与刚性连接情况的比较，定量地分析了柔性连接的影响。     

钢-混凝土组合框架柱的稳定设计方法

针对钢-混凝土组合框架的特点,利用考虑滑移影响的组合梁等效刚度计算方法,考虑组合楼盖的组合效应、组合梁与柱的实际约束程度以及节点的半刚性连接特征等因素,推导出有侧移和无侧移半刚性组合框架柱组合梁的刚度修正系数,提出了有侧移及无侧移组合框架柱的稳定设计方法.算例分析结果表明,该设计方法有效地利用了组合效应和节点的延性,具有较好的经济效益.     

钢筋混凝土梁柱节点变形计算

在中震或大震作用下,钢筋混凝土框架节点核心区的开裂和破坏是不可避免的,刚性节点的假定在弹塑性阶段已不能成立,对钢筋混凝土非刚性节点进行初步理论分析具有重要的理论意义和工程实用价值。因此,文章对框架结构抗侧力体系中框架柱柱顶位移的组成进行了分析,重点研究了框架梁的变形、柱的变形、节点核心区剪切变形对柱顶侧移的影响,其结果可为钢筋混凝土框架结构层间变形的简化计算提供理论依据。     

半刚性梁柱节点连接钢框架柱的计算长度取值初探

本文给出了具有半刚性梁柱节点连接框架梁的弯矩转角位移方程。按此方程导出了无侧移框架和有侧移框架柱的计算长度取值方法。该方法与我国规范规定的计算长度取值协调一致,不过考虑半刚性连接时要对横梁的约束刚度进行适当的修正。     

装配式钢筋混凝土柱-钢梁框架节点抗震性能试验研究

通过4个1/2比例装配式钢筋混凝土柱 钢梁框架节点低周往复荷载作用下的试验研究,分析了节点区加劲腹板厚度及开孔的影响,研究该新型节点连接构造的受力性能及装配式钢筋混凝土柱 钢梁框架单元的抗震性能。基于试验结果对试件的破坏特征、滞回性能及变形组成进行分析。研究结果表明：装配式钢筋混凝土柱 钢梁框架节点滞回曲线呈纺锤形,梁端塑性铰区充分耗散能量,具有良好的抗震性能;装配式螺栓连接钢筋混凝土柱 钢梁混合节点具有良好的连接质量;加劲腹板厚度的增加一定程度上减小了节点的剪切变形,加劲腹板开孔对节点受力性能影响不大;梁弯曲变形引起的层间侧移在强柱弱梁型钢筋混凝土柱-钢梁框架节点总侧移中所占比例最大,节点剪切变形所占比例较小。     

钢框架刚性节点域的研究现状与展望

钢框架刚性节点域的力学性能及其设计方法研究一直在结构工程领域颇受关注.对国内外近期相关研究成果进行较系统的总结分析,着眼于钢框架刚性节点域的受力性能、节点域的剪切变形及其对框架层间侧移的影响、节点域的补强方式3个方面,阐述国内外钢框架刚性节点域研究的进展及其现状,并针对有待于进一步研究的问题提出几点认识.     

多高层钢结构的分类及其稳定性设计

提出了与钢结构稳定性计算有关的多高层钢结构的分类 ,由此可以更好地理解钢结构稳定性的计算方法 ,合理选择钢结构稳定计算的图表或公式 ,判断某些钢结构规范稳定性计算条文的合理性。     

消能摇摆钢框架结构抗震性能的影响因素与设计方法

消能摇摆钢框架结构包含主体钢框架结构、摇摆结构和耗能阻尼器三部分。刚度较大的摇摆结构可以使主体钢框架在地震作用下发生均匀的层间变形,抑制薄弱层产生。布设于摇摆结构底部的阻尼器,能够耗散地震动能量,减小整体结构的地震反应,提高结构的抗震性能。文中对消能摇摆钢框架结构抗震性能的影响因素进行参数分析,并基于我国建筑抗震设计规范的原则提出了抗震设计方法。根据消能摇摆钢框架结构的受力机理,提出简化分析模型,通过弹塑性地震反应分析,验证简化模型的有效性。基于简化分析模型对无量纲参数进行参数分析,根据各参数的影响规律得到无量纲参数的建议范围。结合我国“三阶段”抗震设防要求,提出消能摇摆钢框架结构的设计方法,并结合算例进行验证。研究表明,消能摇摆钢框架结构抗震性能良好,设计合理的摇摆结构与阻尼器能够抑制钢框架的薄弱层、减小结构的地震反应。     

平面钢框架结构极限承载的体系可靠度评价

为了将基于结构体系可靠度的设计理论运用到钢框架结构的设计中,必须对工程中钢框架结构的体系可靠度做出实际的评价。本文考虑影响钢框架结构体系可靠度的主要因素,并根据现有的统计资料,对钢框架结构的体系可靠度做出比较实际的评价,为实现基于整体可靠度的钢框架结构设计奠定了一定的理论基础。     

Behavior and design of reinforced concrete frames retrofitted with steel bracing against progressive collapse

Steel bracing is able to improve progressive collapse resistance of reinforced concrete (RC) frames, but the bracing design is typically based on seismic retrofitting or lateral stability. There is no approach for design of steel bracing against progressive collapse. To this end, a retrofitting approach with steel braces is proposed based on analysis of macro finite element (FE) models with fiber beam elements. The FE models were initially validated through the experimental results of a braced frame and then used to investigate the effects of pertinent parameters on the progressive collapse resistance of planar frames. The results suggest the braces should be placed at the top story. Thereafter, macro FE models are built to investigate the dynamic responses of the three‐dimensional prototype RC frames under different column removal scenarios (CRS) and show the necessity of retrofitting. Accordingly, the design approach of steel bracing is proposed with incremental dynamic analysis (IDA) and assuming independent contribution of braces and frames to resistance. Finally, the fragility analysis of the frames under a corner‐penultimate‐exterior CRS is conducted through IDA and Monte Carlo simulation, and the results confirm the validity of the proposed design approach for retrofitting RC frames.     

竖向荷载下半刚性连接组合框架的实用设计方法(Ⅱ)——梁与柱设计及算例

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。本文为全文的第二部分,介绍梁与柱设计。并通过一个算例,说明竖向荷载下半刚性连接组合框架的实用设计过程及经济性。     

远东商务中心增层改造结构设计

报道了远东商务中心在原9层框架上套建6层新增框架的设计思路。着重介绍了基础选型与设计、保证新增套建框架与原房屋框架协同工作的技术措施、新增套建框架设计计算、新增楼层剪力墙布置等,可供同类工程套建增层时参考。     

Empirical hysteretic energy with strength,strength and drift,and SCWB designs using steel moment‐resisting frames

This paper represents the hysteretic energy performance of twelve steel moment‐resisting frames intentionally designed by three different design procedures. The three types of design procedure were: (1) strength controlled design; (2) strength and drift controlled design; and (3) strong‐column/weak‐beam controlled design. The energy performances of the so‐designed frames were discussed in view of the effects of strength variations, stiffness variations, and plastic mechanism variations, on the hysteretic energy input and its distribution in multiple storey frames. An empirical mean hysteretic energy formula has been proposed based on this study. Copyright © 2001 John Wiley & Sons, Ltd.     

平板式筏基计算方法的改进和简化

平板式筏基为无梁体系 ,传力简捷 ,整体刚度好 ,施工速度快 ,是框架结构常用的基础形式。对等代框架法和经验系数法进行分析比较后 ,提出了适用于平板式筏基的等代梁弯矩系数法 ,并结合新规范对板的冲切计算、受剪计算、弯矩及配筋计算推导了较实用的简化公式和条件式 ,编制了计算表     

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.     

Buckling analysis design of steel frames

Steel design codes do not provide sufficient information for the efficient design of steel structures against out-of-plane failure, and what is provided is often overly conservative. The method of design by buckling analysis (DBA) specified in one code corrects this situation for beams, but the extension of this method to columns is only referred to, while there is no guidance on how to apply this method to the design of beam-columns and frames.Beam DBA uses the design code formulation for the member nominal design strengths in terms of the section moment capacities and the maximum moments at elastic buckling, accurate predictions of which may be determined by computer programs. Column DBA is similar, in that it uses the design code formulation for the column nominal design strengths in terms of the section compression capacities and accurate predictions of the elastic buckling.However, design codes do not provide formulations for the direct buckling design of beam-columns, but instead use the separate results of beam design and column design in interaction equations. The further extension to frames is not directly possible, because frames are not designed as a whole (except through the rarely used methods of advanced analysis), but as a series of individual members. This paper shows how the method of DBA can be used to design beam-columns and frames as well as beams and columns. Two example frames are designed and very significant economies are demonstrated when the DBA method is used.