Seismic Design Of Steel Structures Research Articles

Optimal control of steel structures by improved particle swarm

Active control is one of the modern approaches in seismic design of steel structures. Recently, induced by economic considerations, especially high expenses of control systems, optimality has become an important issue. In this paper an active system is used to control a steel structure’s displacements by a simplified pole assignment method. To optimize the number, the locations, and the total driving force of the required actuators, an improved particle swarm algorithm is presented focusing on the parameters of the velocity equation. A Geographical neighborhood topology and an adaptive inertia weight are used to improve the standard PSO algorithm. In addition to the local and global best solutions, the positions of the best particles in the geographical neighborhood are mathematically represented in an additional term. The performance of the proposed algorithm is compared with the traditional Genetic Algorithm (GA) and the standard particle swarm considering the optimal control of a 12-story steel structure as a numerical example. High capabilities of the proposed method in terms of the control target, convergence rate, and accuracy are simultaneously clarified by the results.

Design Methodologies for Steel Structures in Seismic Regions

This paper is an insight into the recent developments in the design methodologies in seismic design of steel structures. Recent damage throughout the world due to earthquakes have led to the conclusion that the inherent seismic resistance of steelStructures should not be taken for granted. Due to increasing number calamities occurring due to earthquakes per year, new advancements has to be made in the design procedures and material control measures as well as welding practice. We will look into the solutions such as displacementbased design and Assessment procedures alongside the generalization of limit state concepts into a performancebased Design framework. In this paper, recent findings on the material, section, member and sub assemblageLevels are reviewed and possible code applications are highlighted. However our main concern will be moderate seismic zones.

Seismic Design of Steel Structures with Lead-Extrusion Dampers as Knee Braces

Seismic Design of Steel Structures with Lead-Extrusion Dampers as Knee Braces

Optimal seismic design of steel structures by an efficient soft computing based algorithm

The main aim of this study is to propose advanced soft computing techniques for the optimal seismic design of real steel structures subjected to natural ground motion records. For the solution of the optimization problem an efficient combination of the particle swarm optimization (PSO) and adaptive virtual sub-population (AVSP) algorithms is proposed. Also an efficient combination of the adaptive neuro-fuzzy inference system (ANFIS), wavelet transforms (WT) and radial basis function (RBF) neural networks, termed as fuzzy wavelet radial basis function (FWRBF), is proposed to accurately predict the structural responses. The numerical results demonstrate the computational advantages of the proposed methodology.

The 2005 AISC Seismic Provisions for Structural Steel Buildings

The American Institute of Steel Construction (AISC) standard, Seismic Provisions for Structural Steel Buildings, is the reference document for seismic design of steel structures throughout the United States. The 2003 International Building Code (IBC) incorporated these provisions by reference, and the 2002 National Fire Protection Association (NFPA) 5000 Building Code also followed this approach. Since their 1997 publication, the AISC Seismic Provisions have been updated on a regular basis in order to incorporate new developments from post-Northridge earthquake research on moment frames and other work in this area. The latest revision culminated with the publication of a completely new set of provisions in 2005 that is in the same unified format as the main AISC design specification. In addition, this edition makes reference to a new AISC standard for the pre-qualification of seismic moment connections that was also completed in 2005. Coordinated efforts between AISC and the Building Seismic Safety Council (BSSC) are intended to continue the process of keeping the seismic design provisions for structural steel buildings as current as possible. Efforts to coordinate with Canadian standards are also underway. This presentation will summarize the changes incorporated into the 2005 AISC Seismic Provisions and the use of the new moment connection pre-qualification standard. It will also speculate on future modifications and additions to the U.S. seismic design provisions for structural steel buildings.

3차원 탄소성 유한변위해석을 이용한 고강도(POSTEN60, POSTEN80) 원형강교각의 내진성능에 관한 연구

Recently, as steel structures become higher and more long-spanned, application of high-strength steels is increasing gradually. For seismic design of steel structures using high-strength steels(POSTEN60, POSTEN80), analytical method, can describe the large deformation and inelastic cyclic behavior generated by non-proportional cyclic loading, are required. In this paper, cyclic plasticity model was proposed by results of monotonic loading tests ant cyclic loading tests. Three-dimensional finite element analysis is developed by using proposed model and finite deformation theory and verified as compare with experiment result. Using 3-dimensional elastic-plastic finite deformation analysis, seismic analysis of high-strength steel pipe-section piers are carried out. Also, seismic performance of high-strength steel pipe-section piers in parameter of diameter-thickness ratio was clarified. 缀Ѐ㘰〻ሀ䝥湥牡氠瑥捨湯汯杹

Update on the AISC Seismic Provisions

Between the advent of incorporating seismic design provisions into the Uniform Building Code (UBC) in the early 1950s, and the late 1980s, the Structural Engineers Association of California (SEAOC) Seismology Committee was almost completely responsible for the content of these provisions. Spurred on by the federally funded National Earthquake Hazard Reduction Program (NEHRP), in the late 1980s and early 1990s seismic design began to be seen as more of a nationwide issue. During these years, the NEHRP program began to fund the Building Seismic Safety Council (BSSC) to develop model building code provisions for seismic design. The BSSC established a nationally represented committee structure, with technical subcommittees addressing each of the main structural materials, including structural steel. To support this effort, the American Institute of Steel Construction (AISC) established a parallel committee (TC 9) and began the development of a set of seismic design provisions for steel buildings. Over the last ten years, a rational, systematic and efficient process has been instituted to incorporate the latest developments in seismic design of steel structures into building code provisions. This system relies on the coordinated efforts of AISC, BSSC, SEAOC and AWS committees. The process provides a single point of responsibility for the development of these provisions, thus eliminating duplicative effort, and more importantly, the development of competing documents that would result in minor differences that would undoubtedly result in major confusion in application by practicing engineers.

Seismic design of steel structures with buckling-restrained knee braces

Analytical models and a performance-based seismic design procedure were developed for a structure with buckling-restrained knee-braces. The hinge-connected main structural members, such as beams and columns, were designed only for gravity loads, and the knee-braces were designed to resist all the lateral seismic load. The cross-sectional size of knee-braces was estimated using the equivalent damping required to be supplied to meet a given performance objective. Parametric study was performed with design variables such as slope and yield stress of the braces. According to the time-history analysis results of a five-story structure with buckling-restrained knee-braces, the maximum displacement of the model structure turned out to correspond well with the desired target displacement after it is retrofitted by knee braces following the proposed procedure.

Accounting for overstrength in seismic design of steel structures

Accounting for overstrength in seismic design of steel structures

Accounting for overstrength in seismic design of steel structures

Observations during many earthquakes have shown that building structures are able to sustain without damage earthquake forces considerably larger than those they were designed for. This is explained by the presence in such structures of significant reserve strength not accounted for in design. Relying on such overstrength, many seismic codes permit a reduction in design loads. The possible sources of reserve strength are outlined in this paper, and it is reasoned that a more rational basis for design would be to account for such sources in assessing the capacity rather than in reducing the design loads. As an exception, one possible source of reserve strength, the redistribution of internal forces, may be used in scaling down the design forces. This is because such scaling allows the determination of design forces through an elastic analysis rather than through a limit analysis. To assess the extent of reserve strength attributable to redistribution, steel building structures having moment-resisting frames or concentrically braced frames and from 2 to 30 storeys in height are analyzed for their response to lateral loading. A static nonlinear push-over analysis is used in which the gravity loads are held constant while the earthquake forces are gradually increased until a mechanism forms or the specified limit on interstorey drift is exceeded. It is noted that in moment-resisting frames the reserve strength reduces with an increase in the number of storeys as well as in the level of design earthquake forces. The P→Δ effect causes a further reduction. In structures having braced frames the main parameter controlling the reserve strength is the slenderness ratio of the bracing members. In these structures, reserve strength is almost independent of both the height of the structure and the effect of building sway. Key words: seismic design, overstrength factor, reserve strength owing to redistribution, steel moment-resisting frames, steel-braced frames, push-over analysis.

An approach to the seismic design of steel structures based on cumulative damage criteria

AbstractThe applicability of Miner's rule to the assessment of cumulative damage of structural details in steel structures under seismic loading is discussed and validated both numerically and experimentally. Starting from this consideration, a seismic design method is proposed that, based on linear elastic dynamic analyses, takes into account a more precise description of the structural behaviour.The proposed method also leads to the identification of a methodology for the assessment of the q‐factor, based on a comparison of the cumulative damage during an earthquake, estimated by means of dynamic linear and non‐linear analyses. This methodology is discussed with reference to columns of single‐storey buildings, and compared to other methods for the assessment of the q‐factor based on the ductility factor theory.

Role of strain-hardening of steel in structural performance.

In the ultimate limit state design and seismic design of steel structures, it is postulated that the structural members have sufficient deformability or rotation capacity. In this context, the relationship of the plastic deformation capacity of steel structural members and the stress-strain curves of their materials are made clear. Namely, to secure the sufficient deformation capacity of structural members, the yield-ratio (the ratio of yield stress to tensile strength) of material should be reasonably low. For flexural members such as beams and beam-columns, the rotation capacity can be evaluated by the complementary energy of materials more exactly. Scattering of yield stress could give an adverse effect on the strength and deformability of steel structures subject to horizontal loading. In this viewpoint, the upper limits of the yield stress and of the yield ratio should be specified in the material standard.

Seismic code development for steel structures

This paper discusses revisions proposed by the Structural Engineers Association of California for the seismic design of steel structures. Several of the new provisions are drastic departures from current practice and are expected to have a considerable impact on design. The proposed changes are discussed from the perspectives of the practising engineer, the researcher, and the committee that drafted the new provisions.

On California structural steel seismic design

A number of new code developments, largely initiated in California, are taking place in the USA for the seismic design of steel structures. The principal ones are reviewed and commented upon in the paper. Key experimental support for some of the changes is indicated. Major attention is directed to the three main types of steel construction: moment resisting frames, concentrically braced steel frames, and, the relatively new method for seismic design, eccentric bracing. Some of the proposed and possible practical improvements in moment-resisting connections are given: the reasons for some concern over the use of concentrically braced frames for severe seismic applications are discussed; and a brief overview on the application of eccentrically braced steel frames is presented. The paper concludes with a few remarks on future trends and needs in structural steel seismic design.

On California Structural Steel Seismic Design

A number of new code developments, largely initiated in California, are taking place in the USA for the seismic design of steel structures. The principal ones are reviewed and commented upon in the paper. Key experimental support for some of the changes is indicated. Major attention is directed to the three main types of steel construction: moment-resisting frames, concentrically braced steel frames, and, the relatively new method for seismic design, eccentric bracing. Some of the proposed and possible practical improvements in moment-resisting connections are given; the reasons for some concern over the use of concentrically braced frames for severe seismic applications are discussed; and a brief overview on the application of eccentrically braced steel frames is presented. The paper concludes with a few remarks on future trends and needs in structural steel seismic design.

Column design

This paper is the result of deliberations of the Society's Study Group for the seismic design of steel structures.

Materials and workmanship

This paper is the result of deliberations of the Society's Study Group for the seismic design of steel structures.

Concentrically braced frames

This paper is the result of deliberations of the Society's Study Group for the seismic design of steel structures.

Connection design

This paper is the result of deliberations of the Society's Study Group for the seismic design of steel structures.

Beam-column joints

This paper is the result of deliberations of the Society's Study Group for the seismic design of steel structures.