An efficient resizing technique for the design of tall steel buildings subject to multiple drift constraints

This paper presents an efficient resizing technique for the optimum design of tall steel building frameworks. Specifically, an ‘optimality criteria’ method is applied to minimize the weight of a lateral load-resisting structural system of fixed topology subject to constraints on interstorey drift. By exploiting the fact for building frameworks that member forces are relatively insensitive to changes in member sizes, rigorously-derived optimality criteria are shown to be readily satisfied through an iterative pseudo-discrete optimization procedure that converges in but a few cycles to a least-weight design using commercial-standard steel sections. While not considered herein, it is a simple matter to extend the stiffness-based design procedure to account also for strength requirements. Two building framework examples are presented to illustrate the features of the design optimization method.     

Stiffness optimization technique for 3D tall steel building frameworks under multiple lateral loadings

Although today's engineering computer technology allows for precise analysis of the structural response of a building, it does not readily provide insight for economical design. Due to the complex nature of a modern tall building consisting of thousands of structural members, the traditional design method is generally highly iterative and time consuming. This paper describes an efficient computer-based technique for least-weight design of three-dimensional (3D) tall steel building frameworks under multiple lateral loading conditions. Stiffness constraints in terms of interstorey drifts are considered and optimum discrete member sizes are automatically selected from databases of commercial standard steel sections. The technique is remarkably efficient and the optimum design generally converges in a few cycles. The designs of two 3D lateral-load resisting building frameworks are presented as illustrations. The effectiveness and suitability of the technique for the design of large-scale tall steel building frameworks are discussed.     

Optimal lateral stiffness design of composite steel and concrete tall frameworks

This paper presents the optimal lateral stiffness design of composite steel and concrete tall frameworks subject to overall and interstorey drift constraints as well as member sizing limits using an efficient numerical approach developed based on the Optimality Criteria (OC) method. Taking into account the composite interaction between the structural steel and concrete materials, the stiffness-based optimal design problem is first formulated according to the European Code 4 (EC4). The necessary optimality criteria are then derived for the design followed by the construction of an iterative scheme to satisfy these optimality conditions while indirectly optimizing the design problem with multiple constraints. The recursive OC process is then carried out with the initial member sizes obtained from a closed-form solution developed for the similar problem with a single drift constraint. The effectiveness and practicality of the developed optimization approach is further illustrated through a series of framework examples.     

Energy-based design optimization of steel building frameworks using nonlinear response history analysis

Presented in this paper is a design optimization method for steel building frameworks subjected to seismic loading using a nonlinear response history analysis procedure. Minimum weight, minimum seismic input energy and maximum hysteretic energy of fuse members are identified as the three design objectives. Design constraints include the limits on inter-story drift and plastic rotation of member sections. The design optimization method employs a multi-objective genetic algorithm to search for optimal member section sizes from among commercially available steel section shapes. The design method is illustrated for a moment-resisting steel frame of a three-story building. It is concluded the proposed optimization methodology is an effective and efficient application of the capacity-design principle to building frameworks under earthquake loading.     

Zur Leistungsfähigkeit,korrekten Anwendung und Kontrolle von EDV‐Programmen für die Berechnung räumlicher Stabwerke im Stahlbau (Teil 1)

On performance, correct use and control of computer programs for structural analysis of three‐dimensional steel frameworks. Structural analysis of three‐dimensional steel frameworks is normally carried out by means of computer programs based on second or higher order theory. The present article classifies under special consideration of equivalent imperfections, whether these simplified theories are adequate or if additional terms are necessary to obtain sufficiently accurate results in practical engineering in any case. For software producers and users, several simple examples are presented, in order to demonstrate the general performance of a software. Furthermore important hints are given for the correct use of computational software developed for statical framework calculation.     

国家奥林匹克体育中心综合训练馆工程结构设计

国家奥林匹克体育中心综合训练馆是为了满足国家柔道队、摔跤队、网球队备战2008年奥运会的需要而建设的,由附属用房和训练场馆两部分组成。训练场馆由三个大跨双层、高大空间结构组成,属大跨空间结构。结构体系确定时,对混凝土结构、钢-混凝土混合结构和钢结构体系进行了详细的分析对比,结合楼面结构布置研究,最终采用了较为合理的钢框架-V型钢支撑结构体系。屋面设计中,结合建筑功能要求,采用了新颖的预应力索桁架双曲屋面结构体系。采用PMSAP和ANSYS软件进行了计算分析。     

Corrosion damage assessment and monitoring of large steel space structures

Large steel space structures, when exposed to a harsh corrosive environment, are inevitably subjected to atmospheric corrosion and stress corrosion cracking. This paper proposes a framework for assessing the corrosion damage of large steel space structures subjected to both stress corrosion cracking and atmospheric corrosion. The empirical model for estimating atmospheric corrosion based on measured information is briefly introduced. The proposed framework is applied to a real large steel space structure built in the southern coastal area in China to assess its corrosion damage and investigate the effects of atmospheric corrosion on stress corrosion cracking. Based on the results, the conceptual design of the corrosion monitoring system of large steel space structures is finally conducted as the first step for a real corrosion monitoring system.     

Corrosion damage assessment and monitoring of large steel space structures

Large steel space structures, when exposed to a harsh corrosive environment, are inevitably subjected to atmospheric corrosion and stress corrosion cracking. This paper proposes a framework for assessing the corrosion damage of large steel space structures subjected to both stress corrosion cracking and atmospheric corrosion. The empirical model for estimating atmospheric corrosion based on measured information is briefly introduced. The proposed framework is applied to a real large steel space structure built in the southern coastal area in China to assess its corrosion damage and investigate the effects of atmospheric corrosion on stress corrosion cracking. Based on the results, the conceptual design of the corrosion monitoring system of large steel space structures is finally conducted as the first step for a real corrosion monitoring system.     

Controlling sewer systems – a critical review based on systems in three EU cities

The term Real Time Control (RTC) is widely used to describe all types of control systems in sewer systems. Today the term covers everything from the simplest to the most advanced types of control systems, making it difficult to communicate about sewer system control in a precise manner, as well as search and find specific types of control systems for comparison. Through a survey of implemented control systems in three EU cities today and with the perspectives of current research within the field of sewer system control, the needs for a new control system design framework is identified. With the basis of existing frameworks for control system design, a new time-scale dependent framework is proposed. We believe this comprehensive time-scale dependent framework can help water utilities to retrofit and design new control solutions and facilitate knowledge sharing about existing designs.     

Design framework for robotic surgery wards at hospitals: Computational implementation

Robotic surgery is one of the most recent technologies in healthcare building field. Due to the design complexity of Robotic surgery wards, computational implementations are being developed to either measure the effect of inserting advanced technologies as Electronic medical recorders and tele surgery, or evaluate design alternatives on healthcare building. This paper presents a design framework that responds to the need for coordinating design phases for Robotic Surgery Wards (RSWs) computationally. This proposed design framework for RSWs can generate functional RSW alternatives and more than one solution for each alternative. The framework has been structured based on the main architectural considerations of RSWs which are geometric and topological, the economic considerations, specific developed pools for shape and corridor patterns, and the theory of “Shape Grammars"has been utilized to compute the framework to generate a vast number of design alternatives. Accordingly, a computational implementation has been established to assist designers in early design stages. Numerical validation for the applications of the developed framework and implementation has been conducted by using reference examples of RSWs. The main finding in this paper is providing healthcare building designers with a computational implementation that generates RSW alternative computationally based on specific shape and cost levels.     

Getting control of multi-project organizations: Combining contingent control mechanisms

The literature on management control has expanded considerably in the past few decades, yet only a limited number of publications have been devoted to multi-project organizations (MPOs). This is somewhat a problem given the increasing rise and importance of project-based structures and the role of project management as a significant part of many firms' management control system. This paper elaborates on a contingency framework of management control in MPOs and aims at investigating the control issues that call for holistic frameworks of control mechanisms. Relying on a comparative case study, the analysis shows how control mechanisms are deployed and what implications different choices of management control systems have on the organizational structure of MPOs. In particular, the paper addresses the importance technical complementarities, and the role of ‘project interdependencies’ and ‘project openness’ for the design of management control system.     

Externally post-tensioned carbon FRP bar system for deflection control

Externally post-tensioned steel tendons have long been an attractive option for increasing the design loads or correcting strength and serviceability problems in bridge and building structures. More recently, alternative solutions have been developed and implemented that use straight post-tensioned carbon fiber reinforced polymer (CFRP) tendons, ideally enlisting their high-strength to failure, small relaxation, corrosion resistance, and light weight. In this paper, a novel CFRP system for external post-tensioning is presented. The solution consists of unbonded CFRP bars connected to dead- and live-end steel anchors by means of couplers that allow the bar to develop the full tensile strength. Intermediate deviators can be extended vertically to impart additional post-tensioning (PT) force and achieve a profiled bar configuration. The required uplift forces for deflection control of a flexural member are provided by modifying the number, position and extended height of the deviators, similarly to commercially available systems that use steel wire strands. The structural efficiency of such approach in controlling deflection is analyzed and discussed for single-span one-way members on the basis of a parametric study that considers the influence of member geometry, flexural stiffness, boundary conditions, and PT system layout. A design example is also provided.     

基于性能的建筑结构抗震设计

就基于性能的建筑结构抗震设计的几个关键环节进行了讨论 ,给出了结构整体设计的总框图及设计中各关键环节的子框图 ,较为清晰地展现了基于性能的建筑结构抗震设计的基本过程。     

Application of corrugated plates as the web of steel coupling beams

Nowadays, steel coupling beams are used as an efficient alternative to reinforced concrete (RC) coupling beams. Particularly in the coupled shear walls system, coupling beams are the main members for dissipating seismic energy. In this paper, for the first time the application of corrugated plates as the web of steel coupling beams (rather than flat web and its stiffeners) is studied as a proposition for improving seismic behavior of such beams. The study addresses the linear elastic buckling analysis and non-linear analysis of steel coupling beams with flat and corrugated webs using finite element technique for which ANSYS software is employed. 160 models have been studied, considering parameters such as shape of web plate (flat and three corrugated types, including trapezoidal, curved, and zigzag), web thickness, number of corrugations, and corrugation angle. The finite element results are validated through comparison with the experimental results of a common steel coupling beam, tested by other researchers. In addition to the advantages of eliminating web stiffeners, results of this study show that the application of corrugated web with the proposed geometric criteria makes it possible to achieve further rotation capacity in comparison with common steel coupling beams. Finally, a design approach for corrugated web of steel coupling beams, accompanied by a practical example, is presented.     

Structural assessment of current steel design models for transmission and telecommunication towers

The usual methods of structural analysis involved in the design of steel telecommunication and transmission towers tend to assume a simple truss behaviour where all the steel element connections are considered hinged. Despite this fact, the most commonly used tower geometries possess structural mechanisms that could compromise the assumed structural behaviour. A possible explanation for the structure stability is related to the actual behaviour being close to semi-rigid connections instead of the assumed hinged connections. This paper proposes an alternative structural analysis modelling strategy for the steel tower design considering all the actual structural forces and moments combining three-dimensional beam and truss finite elements. Comparisons of the two above-mentioned design methods with a third method based on the use of spatial beam finite elements to model the main structure and the bracing system on two actually built steel telecommunication towers (40 and 75 m high steel towers) are described. The comparison is based on an extensive parametric study of the tower geometry in order to access the structural tower ultimate and serviceability limit states.     

异形柱框架结构的特点与设计

对异形柱框架结构与矩形柱框架结构在设计中的区别进行了分析,从异形柱框架结构的整体计算分析方法方面进行了阐述,为从事异形柱框架结构设计工作带来一定帮助。     

泰达市民广场多折面钢结构及拉杆桁架支承体系和膜结构设计与研究

天津泰达市民广场多折面大斜坡由两折面钢结构桁架与三折面拉杆桁架幕墙支承结构及置于二者之上的六块骨架式膜结构组成。对两折面钢管桁架与三折面幕墙支承结构体系的传力路径、受力特点进行了分析和探讨,并基于建筑美观的要求,提出了大斜坡钢结构沿纵向设置伸缩缝释放温度应力的铰接-滑移节点及连接形式;应用多链杆一体化计算模型研究了膜材与骨架支承体系之间的相互作用,并通过模态分析揭示了其刚度分布;分析了结构设计中特殊节点的受力机理并提出了节点的设计及构造方法。     

Progressive-Failure Analysis of Buildings Subjected to Abnormal Loading

Abstract: This article presents a progressive‐failure analysis procedure to evaluate the performance of a building framework after it has been damaged by unexpected abnormal loading, such as an impact or blast load caused by a natural, accidental, or deliberate event, or as a result of human error in design and construction. To begin with, it is assumed that some type of short‐duration abnormal loading has already caused some form of local damage to the structure. The residual load‐carrying capacity of the remaining framework is then analyzed by incrementally applying the prevailing long‐term loads and any impact debris loads, and progressively tracing the strength deterioration of the structure until either a globally stable state is reached or progressive collapse occurs for part or all of the structure. The computer‐based procedure is based on the displacement method of analysis. The effect of both axial force and shear deformation on member and structure stiffness is accounted for in this article (Liu, 2004; Xu et al., 2004). The stiffness matrices for framework members account for elastic–plastic bending, shearing, and axial deformations, and are progressively updated under incrementally increasing loads through the use of degradation factors that characterize stiffness deterioration. The computational model allows the incremental analysis to proceed beyond loading levels at which structural instabilities occur, including the formation of plastic collapse mechanisms and the disengagement of members from the building superstructure. The progressive‐failure analysis procedure is quite general and, with the appropriate choice of material constitutive model, may be applied to building frameworks of any type (concrete, steel, composite, etc.). Herein, a constitutive model for structural steel is adopted to account for elastic–plastic behavior under single or combined forces, and the progressive‐failure analysis procedure is illustrated for two example planar steel moment frames.     

Capacity reduction and fire load factors for LRFD of steel columns exposed to fire

Capacity reduction and fire load factors corresponding to the load and resistance factor design (LRFD) format are developed for steel columns exposed to fire. A sample deterministic framework to determine fire and steel temperatures and the capacity of steel columns is adopted for this analysis to structure the methodology. A specific number of parameters that affect the structural response, including the fire load, ratio of floor area to the total area of the fire compartment, opening factor, thermal absorptivity of compartment boundaries, thickness, density and thermal conductivity of insulation, dead load, and live load are taken as random variables. Mechanical and sectional properties of steel (e.g., yield strength, cross-sectional area, etc.), are also considered to be random variables. The effect of active fire protection systems (e.g., sprinklers, smoke and heat detectors, fire brigade, etc.), in reducing the probability of occurrence of a severe fire is included. Given the choice of framework and based on detailed reliability analyses, it is shown that the capacity reduction and fire load factors should vary depending on the presence of active fire protection systems in a building.