日本现存高层钢管混凝土建筑的结构特性

高层建筑中广泛使用钢管混凝土柱作为结构构件。收集了日本1968~2013年间设计的159座高层钢管混凝土建筑的结构特性数据,分析了不同设计阶段现存高层钢管混凝土建筑的结构布置和抗震设计参数。得到以下结论:不同阶段,结构所用的混凝土强度等级不断提高,因此结构的楼层数和楼层高度不断增加;近几年,隔震结构和消能减震结构的数量大幅增加;高层钢管混凝土建筑倾向于使用和钢结构建筑几乎相同的设计基底剪力系数。     

钢-混凝土组合梁在某建筑大楼室内增层改造加固中的应用

建筑物由于原设计不足或因改变使用用途等,需要对其进行改造和加固。结合实际工程,介绍了钢-混凝土组合梁在房屋室内增层改造加固中的应用。实践证明,钢-混凝土组合梁与其他梁相比,节点处理灵活,跨越能力大,从而可以减小楼盖高度、增加楼层净高,降低结构自重,另外还可以节省支模,缩短施工周期。     

沈阳皇朝万鑫大厦钢管混凝土施工技术

万鑫大厦钢管混凝土结构由40根钢管组成,高约65.5 m,按楼层进行分段.针对该工程钢管混凝土结构建筑物高、混凝土泵送难及施工中容易出现堵管、爆管和混凝土养护等特点,重点介绍了克服难点所采取的技术措施及施工方案.     

天津市地铁大厦超高层建筑结构设计的研究

天津市地铁大厦高度为176m，属于超高层建筑。结构采用混合结构体系，结构形式为框架-混凝土核心筒体系，外框架结构的框架梁采用型钢混凝土梁，框架柱进行了优化设计，采用2个方案进行了深入的比较分析研究。第一方案采用型钢混凝土柱，第二方案采用圆钢管混凝土柱，通过比较分析，前者柱截面较大，影响了建筑使用面积，且用钢量较多，但对结构整体刚度贡献有所提高。第二方案采用钢管混凝土柱，截面缩小了20％，增加了使用面积，钢材节约20％左右，且施工简单，结构整体刚度满足设计要求，特别是其延性性能优越。通过研究，本工程采用钢管混凝土柱-型钢混凝土梁框架-混凝土核心筒结构体系，使工程经济造价合理，且结构抗震性能达到国内同类高度的超高层建筑水平。     

不同结构体系钢管混凝土框架地震响应对比

对SSI与刚接两种条件下四层钢管混凝土框架结构体系进行了模态分析与模型验证,并在此基础上对4层、8层、12层3种不同高度楼层的钢管混凝土框架结构体系进行了非线性地震响应分析。通过模态试验分析,获得考虑SSI影响后会使结构体系自振频率减小,周期增大,并在高阶模态会出现提离现象。选取了3组地震动对3种不同楼层高度的结构进行非线性地震响应时程分析,获得考虑SSI作用未必均会使结构体系的地震反应放大,其具体情况应视结构的自振周期与地震波的主要特征频率的关系。SSI对钢管混凝土框架结构的地震响应有一定的影响,在抗震设计中应该进行适当考虑。     

超高结构框架柱选型研究

在超高层建筑的结构设计中,选择合理高效的抗侧力体系不但可以节约材料用量、缩短工期,还可以增加楼层的有效使用面积。型钢混凝土柱(SRC柱)和钢管混凝土柱(CFT柱)是超高层建筑中两种常用的框架柱截面类型,两者的力学性能、施工性能和经济性能等各有优劣。以某300m高超高层建筑为案例,分别采用型钢混凝土柱和钢管混凝土柱两种框架柱截面,从受力性能、工程造价、防火防腐性能、施工性能、质量检测和节点构造等方面比较了两种方案的优劣性,相关结论供同行在实际工程的框架柱方案选型时参考。     

新型钢管空心混凝土板技术

为满足大跨度建筑的楼层净高的要求,控制楼板水平受力构件的高度,提高楼板承载能力,提出一种新型的楼板结构——钢管空心混凝土板。将钢管、钢箱梁、钢管柱组成的钢框架结构与楼板混凝土有效地结合在一起,整体受力,从而减轻楼盖重量、减小截面尺寸、提高楼盖结构的承载能力。     

武汉某250m超高层建筑混凝土结构和混合结构设计方案及造价对比

对于武汉某250m超高层建筑,在结构设计方案阶段,设计了混凝土结构和混合结构2种结构方案,对2种方案的优势和劣势进行了分析,并对结构材料造价进行了对比.结果表明,2种结构方案均可行,采用混凝土结构方案可大幅降低结构造价,采用混合结构,施工速度快,可缩短项目施工周期,但结构材料造价相对较高.论文分析结果对建设单位、设计单...     

某超高层建筑施工监测与分析

由于荷载的增加和混凝土的收缩徐变,超高层建筑在施工过程中会产生附加内力和变形,有必要对结构展开施工监测。通过对某超高层建筑开展为期680d的施工监测,研究施工过程中钢管混凝土柱与钢筋混凝土剪力墙的应变发展规律;同时,利用有限元方法分析了主体结构封顶后竖向变形的分布特点与成因。研究表明,随着时间的增加,同一楼层的钢管混凝土柱竖向应变增量明显大于剪力墙,但各构件的应变增量处于可控范围内;由混凝土徐变引起的钢管混凝土柱和钢筋混凝土剪力墙的竖向变形最多分别可达总变形的29.9%和33.5%,徐变引起的结构变形应予以充分重视。     

广州新电视塔钢管混凝土施工技术

广州新电视塔钢管混凝土结构由24根高约454m的倾斜钢管组成.针对楼层分段分布、结构镂空、混凝土泵送难和检测难的特点,在施工前进行低收缩混凝土的模型试验,确定钢管混凝土无裂缝,满足设计要求.并根据施工过程中容易出现堵管、爆管和混凝土养护等问题,采用布料杆和选择混凝土配合比来确保顺利施工.同时,对钢管混凝土进行体内埋管超声波检测,检测效果良好.     

Ring-Shaped Lateral Bracing System for Steel Structures

Buckling of compression members has a great impact on the reduction of energy dissipation capacity and ductility of the structural system such as concentrically braced frame systems (CBFs). As well, direct connection of tensile and compression members to beams and designation of the link beam as a fuse, and the formation of plastic hinges in the link beam in eccentrically braced systems (EBFs) endanger the safety of this type structural systems. This paper introduces a new ring-shaped lateral bracing system so-called the Shami lateral bracing system (SLBs) which removes the common tensile and compressive members along with their connections to the structure. As a substitute, SLBs introduces a new element with proper ductility and energy dissipation capacity and could be an appropriate alternative to the existing systems. Because of the high degree of statically indeterminacy of the proposed system, the structural stiffness does not lead to a steep reduction after the formation of the first plastic hinge. The performance of this lateral system is evaluated by numerical modeling, and the results show that the structures resist against the lateral loads with acceptable seismic performance. It seems that this system in comparison with CBF and EBF systems may not be cost-effective for bending of the ring, welding, etc., but from the seismic performance points of view, it has good performance.     

深圳市太古城花园结构设计

通过深圳太古城花园项目结构设计实例,介绍建筑功能较复杂的城市综合体建筑群的结构布置、选型、构件设计和技术措施等,供同行参考。     

地震区框架-剪力墙结构最优剪力墙数量的研究

本文从沿高变刚度框剪结构协同分析的连续 离散化分析原理出发 ,提出了确定地震区沿高变刚度框剪结构剪力墙最优数量的简化计算方法。首次提出了采用竖向构件分类的方法确定最优剪力墙数量。本文方法具有较高的精度 ,可用于结构的初步设计阶段     

结构系统风致疲劳寿命可靠性分析

工程结构一般是由很多构件组成的超静定结构。在风荷载作用下,一个或者几个构件发生风致疲劳破坏不一定导致结构系统失效。首先,结合风速风向联合分布等风荷载特征,给出计算结构系统风致疲劳寿命失效概率的计算流程。其次,由风洞试验结果对目前世界最高的电视塔——610m的广州新电视塔的天线结构进行风振响应分析,风振响应计算中考虑塔身结构的振动对天线结构响应的影响。最后,在以上两步分析的基础上,对该天线结构系统的风致疲劳寿命可靠性进行计算。计算结果表明:用阶段疲劳寿命分枝-约界法识别出17个主要失效模式;S-N曲线中随机变量的参数对主要失效模式的失效概率影响较大;用蒙特卡罗方法计算的100年设计寿命相应的这一实际天线结构的风致疲劳失效概率为4.2%左右。     

中日欧美抗震规范结构影响系数的构成及其对塑性变形需求的影响

本文对中、日、欧州及美国地震规范地震力计算的结构影响系数的构成进行了分析,认为,美国的结构影响系数中包括了材料的强屈比、超静定结构体系的超强系数以及延性系数;而欧洲的结构影响系数包含了延性系数,对于延性好的结构还允许包含结构体系的超强系数;日本仅包含延性系数;我国也是仅包含延性系数。由于日本采用允许应力设计,还有一个1.4的安全系数,因此比较起来,日本的地震力最大。从结构影响系数的构成看结构在地震作用下产生塑性变形的深度,按照美国规范设计的结构塑性变形要求最高,欧洲次之,我国再次之,按照日本规范设计的结构塑性变形要求最小。     

Zur Vereinheitlichung der Stabilitätsregeln im Eurocode 3

Unified stability rules in Eurocode 3. During the conversion of the ENV‐Eurocode 3 to the EN‐Eurocodes 3 the stability rules for beams‐columns (flexural and lateral torsional buckling), for built up members (plate buckling) and for shell structures (shell buckling) could be harmonized in using a common method with reduction factors ρ from buckling curves that can be determined with a global slenderness depending on the structural system and its loading conditions. This procedure and its justification according to EN 1990 Annex D – Design assisted by testing – which is used to determine the partial factors from tests is presented. The procedure allows to assess structures and structural members that so far were not accessible to simple numerical verifications.     

Estimation of system-level ductility demands for multi-story structures

System-level ductility is an essential factor for earthquake resistant design of structures. It is related to the response modification factor (or force reduction factor), commonly used in aseismic design procedures. The ductility demands for single-degree-of-freedom structures or individual structural members can be determined easily. However, there is no established method of determining the ductility demands for structural systems. The object of this study is to develop a method for the estimation of the ductility demand at the structural system level. The validity of the proposed method has been examined for several cases of different structures and different earthquake excitations.     

Cyclic responses of thin-walled structural steel members subjected to three-dimensional loading

This paper presents an experimental investigation of the cyclic responses of thin-walled structural steel members under an earthquake-induced, coupled three-dimensional load. Nine thin-walled structural steel members were tested under various load combinations to investigate the correlation among bending, axial load and torsion. Bending capacities of tested members were compared to distinguish the effects of torsion, axial load and their combination in affecting a member's bending performance. Test results show that members' bending strength is reduced when axial load is applied. Further reduction in member performance is exhibited when coupled torsion and axial load are both present; this reduction demonstrates the necessity for including torsion in calculating a member's bending strength when buildings are designed to be earthquake-resistant.     

Distributed Control of Large-Scale Structural Systems

This article develops a methodology for the distributed active control of large structural systems. The central idea is to use a set of active members in a structural system, each {locally} controlled. The method relies on an understanding of (1) the peculiar interaction of force feedback and velocity feedback in an active member and (2) the interaction between such active members, as well as that between active and passive members in a structural system. Using a commonly occurring MDOF model of a structural system, we show that the distributed-local-control design is robust. Locating the active members so that all the eigenvalues of the damping and stiffness matrices of the controlled system are assuredly increased leads to several results on where and how active members might be located in such a structure.     

Thermal bowing on steel columns embedded on walls under fire conditions

The contact of steel columns with building walls is responsible for huge thermal gradients within its cross-section during fire. Current regulatory codes for fire design of steel members provide a formulation to assess the load-bearing capacity of these members assuming uniform temperature through the cross-section; however, this is not what happens in the major part of the cases in real structures where the columns are embedded on walls. The walls on one hand will provide a temperature reduction on the columns, which is somehow favourable in terms of its fire resistance, on the other hand the differential heating on the columns cross-section may lead to unfavourable stresses (bending moments) responsible for instability (thermal bowing). Considering that the structural behaviour of columns is strongly dependent of the second order effects this is an important phenomenon which may lead to a significant reduction on its fire resistance. This paper presents the results of a numerical study to assess the influence of the differential heating on the fire design of steel columns. New interaction axial force–bending moment diagrams for non-uniformly heated H steel columns are proposed.