Journal articles on the topic 'AISI Design Provision'

As a result of failures uncovered after the Northridge earthquake, the AISC Seismic Provisions for Structural Steel Buildings has become extremely stringent in its design provisions for moment frame structures. Although the changes are justified, they are not necessary for every type of building system. Some structures can be safely designed to resist earthquake forces elastically without concern of structural collapse. Metal buildings are typically lightweight, and small inertia forces from the design earthquake will not usually result in an inelastic response of a system that is properly designed to resist wind forces. In this paper, metal building systems are analyzed using an equivalent lateral force method and a linear time history analysis to show that typical metal building systems will respond elastically to the design earthquake. Specifically, using the International Building Code along with the aforementioned document, it is shown in the following sections that for lightweight metal building structures, adherence to the AISC Seismic Provisions for Structural Steel Buildings is not required in most cases except for locations on the West Coast and a few regions east of the Rocky Mountains. Elastic design methodology is discussed and design recommendations applicable to metal building systems are provided.

This paper addresses the applicability of the provisions of Chinese (GB50018-2002, effective width method) and the AISI Specifications (AISI-DSM, direct strength method) to estimate the load-carrying capacity of cold-formed steel lipped channel columns. It is worth noting that GB50018-2002 and AISI-DSM adopt different approaches to perform this task: while the former is based on the “Effective Width” concept, the latter may adopt the ‘‘Direct Strength Method’’. First, the relevant aspects related to the experimental investigations are briefly presented. Then, an extensive numerical study is performed by them, the estimates provided by them are compared with the experimental values. On the basis of these comparisons, some concluding remarks are drawn concerning the application of the GB50018-2002 and AISI-DSM design approaches.

The beam–column interaction equations of the Canadian Standards Association Standard CAN3-S16.1-M84 "Steel structures for buildings — limit states design" are reviewed and areas of concern in the formulations are addressed. The interaction equations developed for the 1989 edition of the standard, CAN3-S16.1-M89 "Limit states design of steel structures," and the methods of dealing with the areas of concern in the previous standard are presented. The new standard requires that at least an approximate second-order geometric analysis be carried out. For frames dependent on the frame stiffness for lateral stability, no longer is the traditional method, using effective length factors greater than one, allowed. Unlike the current American Institute of Steel Construction "Load and resistance factor design'' (AISC LRFD) specification, two sets of interaction equations, one for in-plane member strength and the other for out-of-plane stability, are used. This results in considerably less unnecessary conservatism. In both sets of interaction equations, the component of the moment due to translation is increased by the second-order effects. The "double ω" problem has been resolved and the minimum sway effects for the gravity loading case have been increased substantially to guard against sidesway buckling. A design example using the new standard is given. By means of a series of analytical examples, the requirements of S16.1-M89 are compared with the traditional method of S16.1-M84. For frames with direct-acting bracing, S16.1-M89 gives interaction values about 1.15 times those of the previous standard with a coefficient of variation of 0.08, while for unbraced frames the corresponding values are 0.98 and 0.07. The S16.1-M89 values reflecting greater rigor in a number of areas are considered the more valid. The S16.1-M89 standard would give comparable results to the AISC LRFD specification for class 1 sections when out-of-plane behaviour governs. The latter specification does not specifically cover cross-sectional strength and in-plane behaviour as does S16.1-M89. Key words: beam–column, stability, strength, bending, compression, standards.

The main focus of this study is to investigate the clip-angle connections are described the section based on ideal limit states. The connection components are designed in accordance with the 2001 AISC-LRFD Specifications and the 2005 AISC Seismic Provisions. In the suggested clip-angle connection, the structural beam can be connected to the column using six high-strength bolts. The slippage on the shear faying surface contributes to increasing energy dissipated capacity in the connection behavior. The design of the clip-angle connection should include these mechanical characteristics. Therefore, this study presents new design methodology that can be applied to bolted clip-angle connections. Besides, step-by-step procedures for design will be treated herein.

In the current 2005 AISC specification, the in-filled light-weight concrete strength (fc´) of concrete-filled tube (CFT) columns is set in the range of 21~ 42 MPa, but with no real substantial testing data to confirm and verify the provisions. Research work related to rectangular column sections with light-weight concrete is rather limited and deserves further investigation. Eighteen rectangular tubes filled with light-weight concrete with fc´ varying from21.4 to43.5 MPa were tested. A special kind of light weight aggregate using find sediment deposits dredged from a local reservoir in Taiwan were used in this experimental study. Formulas for CFT columns as specified in the design code AISC Specification were examined and compared. The test results actually show that the further lower fc´ values are possible and that the 1999 AISC-LRFD provisions yields conservative design results. For the fc´ range specified in the 2005 AISC specification is found to be in good agreement with the test results

Steel ordinary moment frames (OMF) are seismic force-resisting systems that can be used in buildings. In current seismic design and detailing provisions, such as the American Society of Civil Engineers ASCE/SEI 7-10 (2010) , American Institute of Steel Construction ANSI/AISC 341-10 (2010), and ANSI/AISC 358-10 (2010) , less stringent design and detailing requirements are specified for steel OMFs compared with those for steel special- and intermediate-moment frames. The strong-column weak-beam (SC/WB) requirement is not enforced for steel OMF connections. In the present study, the seismic performance evaluation is conducted for steel OMFs designed according to current seismic design and detailing provisions considering different combinations of gravity, seismic, and wind loads, as well as wind drift limits. Based on the results of seismic performance evaluation, permissible structural heights for steel OMFs are also proposed.

This paper presents an overview of the proposed changes in composite design provisions for the upcoming American Institute of Steel Construction (AISC) 2005 Specification. The main change insofar as member design is concerned relates to how composite column design is handled. The new provisions will provide a more smooth transition between design of composite and reinforced concrete columns and a more rational, mechanistically-based design procedure. Insofar as member detailing is concerned, the main change is in the strength values for shear studs, which have been considerably lowered under some circumstances. The paper also presents some ongoing developments in composite floor and lateral load resisting systems, and concludes with a short description of an unusual composite truss.

This paper is mainly performed to investigate T-stub connection that is described on the basis of ideal strength limit states. The determination of T-stub based on the full plastic strength of the steel beam in accordance with 2005 AISC Seismic Provisions. The T-stub connections considered herein were performed to include the T-stub component of bolted moment connection frames. Therefore, the proposed T-stub models will be evaluated by comparing the required factored bar strength. T-stub components using ten high strength bolts with wider gages are demonstrated in this design. In addition, equations for connection design will be described in this paper. Finally, new design methodology is applied to T-stub connections suggested in this study.

Barrel vaults are effective semi-cylindrical forms of roof systems that are widespread for multipurpose facilities including warehouse, rail station, pools, sports center, airplane hungers, and community centers because of providing long-span and economical roof with significant amount of space underneath. In the present study, size optimization of double-layer barrel vaults with different configurations is studied. Four recently developed algorithms consisting of the CBO, ECBO, VPS, and MDVC-UVPS are employed and their performances are compared. The structures are subjected to stress, stability, and displacement limitations according to the provisions of AISC-ASD. The design variables are the cross-sectional areas of the bar elements which are selected from steel pipe sections. The numerical results indicate that the MDVC-UVPS outperforms the other algorithms in finding optimal design in all examples.

The effectiveness of the measures provided in the 2005 American Institute of Steel Construction (AISC) Specification for elastic distortional buckling of doubly symmetric I-shaped flexural members with slender webs was evaluated in a previous study. It was demonstrated that the code equations generally provide conservative strength estimates for the slender-web I-beams, and the amount of the conservatism was found to be rather dramatic for some cases. As a continuation of this effort, the effectiveness and accuracy of the 2005 AISC code provisions as well as predictions for elastic distortional buckling of slender-web singly symmetric I-shaped members is investigated in this paper. Comparisons are made with the finite strip analysis results for distortional buckling and the two design equations for elastic distortional buckling proposed by other researchers. It is demonstrated that the code predictions are by and large conservative, and even overly conservative in some cases, which does not seem to be justifiable economically.

A reduced beam section with a bolted web (RBS-B) connection is permitted for use only in intermediate moment frames (IMF) according to the ANSI/AISC 358-05. This is because some RBS-B test specimens failed to achieve 4% total rotation capacity, which is the minimum story drift angle required for special moment frames (SMF). Several studies reported that some RBS-B connections could experience brittle connection fracture during earthquakes, which can also be detrimental to the seismic performance of IMF systems with RBS-B connections. For investigating whether IMFs with RBS-B connections provide a satisfactory seismic performance, this study evaluated the seismic performance of IMFs with pre-qualified RBS-B connections following the ATC-63 procedure. Twenty-four model buildings were designed according to current seismic design provisions. Several IMFs with RBS-B connections do not satisfy the acceptance criteria specified in ATC-63.

The main objective of this study is evaluating the seismic behavior of composite columns in MRFs subject to dynamic loads.The design Codes of composite structures contain different views in some cases and therefore conservative provisions, because of lack of enough information about the behavior of these structures. The base shear and moment of structures in non-linear state can be considered as criteria for the potential of a lateral-force-resisting system to dissipate the seismic energy.Lower values of non-linear seismic base reactions indicate better efficacy of the system. In this study the performance of the MRFs with composite columns has been evaluated using 8-story structural models, considering the base reactions obtained from the non-linear analysis. Analytical modeling has been performed based on the AISC Code. The results show good performance of composite sections under the seismic loads. Also, a comparison between two types of composite sections, the full and half-embedded steel sections in concrete, has been made.

The AISC 2002 Seismic Provisions for Structural Steel Buildings recommend that usage and sizing of beam flange continuity plates across the column web shall be based on tests. The Recommended Seismic Design Criteria for New Steel Moment-Frame Buildings ( FEMA-350) state that unless project-specific testing is performed to demonstrate that continuity plates are not required, moment-resisting connections should be provided with continuity plates when the thickness of the column flange is below a minimum value. One of the preferred moment connections for seismic-resistant steel frames is the reduced beam section (RBS) moment connection, which has performed well under cyclic loads in laboratory testing. To demonstrate the effectiveness of the RBS moment connection without continuity plates in the panel zone, a series of four full-scale tests of exterior beam-column connections was carried out. All materials were A572 Grade 50 steel; the beams were W30×132, two of the assemblies used W14×283 columns, and the other two used W18×211 columns. The beams were welded to the columns using complete joint-penetration welds. All four tests demonstrated that the RBS connections without continuity plates developed a total interstory drift angle greater than 0.04 radians and met the requirements for special moment frames.

In recent years, rapid advances have taken place in earth-quake engineering as applied to steel structures with major emphasis given to (1) development of advanced procedures for seismic performance assessment, (2) development of advanced design procedures for plastic mechanism control, (3) improvements in structural design detailing, (4) better modeling of members and connections for dynamic non-linear analyses, (5) development of new damping devices for supplementary energy dissipation, (6) development of self-centering structural systems, (7) development and testing of new design strategies for reducing structural damage under severe ground motions. Even though such advances have reached in some cases a refinement level justifying their in-troduction in seismic codes, the updating of Eurocode 8 with design criteria and new design strategies reflecting newly developed knowledge is still in delay. In the actual version of Eurocode 8, some advances, such as new structural ty-pologies like braced frames equipped with buckling re-strained braces and dissipative truss moment frames, are still not codified even if they have already gained space in American codes. Because of these rapid advances, weaknesses of Euro-code 8 and new structural typologies to be codified have been recognized and a document focusing on such weak-nesses and new research needs has been published [1]. In particular, the sharing of knowledge obtained has been rec-ognized to be critical to improve the seismic design of steel structures. Therefore, a Thematic Issue on “New Advances in Seismic Design and Assessment of Steel Structures” can be considered timely. Many researchers, all joined by the common interest in design, testing, analysis and assessment of steel structures in seismic areas, have accepted to contribute to this special is-sue. As a result, this thematic issue is composed by eleven contribution covering important design topics for seismic resistant steel structures. Two works [2, 3] are devoted to the seismic design of Concentrically Braced Frames (CBFs), pointing out the drawbacks of the design provisions suggested by Eurocode 8 and also reported in the Italian Technical Code for Construc-tions. In particular, the need to revise the design procedure suggested for columns of CBFs is discussed showing that both the stability and resistance indexes of columns are often exceeded. The results obtained are in agreement with those presented by other researchers [4-8] who recommended de-sign procedures based on a rigorous application of capacity design principles. Also the third manuscript of the thematic issue is devoted to CBFs, but aiming to the development of a new buckling restrained system which can be easily dis-mounted [9]. As it is well known, buckling restrained braces (BRBs) are basically constituted by two parts: an internal slender steel member, known as the “core” and a restraining member, known as the “casing”. The core component has the key role of dissipating energy, while the casing component restrains the brace core from overall buckling in compres-sion. The buckling restraining mechanism can be obtained by enclosing the core (rectangular or cruciform plates, circu-lar rods, etc.) either in a continuous concrete/mortar filled tube or within a “all-steel” casing. Despite of the use of such braces allows to obtain wide and stable hysteresis loops, thus overcoming the main drawbacks of traditional braces due to the poor cyclic response resulting from overall buckling, and their design is already codified in ANSI/AISC 341-10 [10], their use is still not codified in Europe testifying an impor-tant weakness of Eurocode 8. Two papers of the present thematic issue are devoted to beam-to-column connections [11, 12]. The first one [11] presents the results of a wide experimental program recently carried out at Salerno University dealing with extended end plate connections, with and without Reduced Beam Section (RBS), connections with bolted T-stubs and, finally, innova-tive connections equipped with friction dampers. The second work [12] is mainly devoted to the theoretical development of the analysis of the influence of gravity loads on the seis-mic design of RBS connections. In particular, it deserves to be underlined that such influence is commonly neglected in codified rules, such as ANSI/AISC 358-10 [13], because experimental tests constituting the base of the recommended design procedures are typically based on cantilever schemes where gravity loads are not applied.

Multiple theoretical frameworks support the notion of interactional feedback as facilitative of second language (L2) development. However, research demonstrates that learners often avoid providing feedback during peer collaborative work, thus failing to take advantage of key opportunities for language learning and development. Recent studies have examined how metacognitive instruction (MI) may be used to explicitly train learners in the provision of interactional feedback, with results showing increased instances of feedback (Fujii et al., 2016) and improved L2 outcomes (e.g., Sato & Loewen, 2018; Sippel, 2019). Building on this work, this exploratory study investigated the effects of MI on intermediate L2 English learners’ (n = 26) provision of interactional features in synchronous computer-mediated communication. Using a pretest-treatment-posttest design, all learners completed three decision-consensus tasks, with learners in the treatment group receiving direct instruction on the benefits of interaction via an instructional video, a practice task, and subsequent whole-class debriefing. The control group completed the tasks without MI. Results demonstrate that learners’ provision of interactional feedback and language-related episodes increased following MI, with qualitative measures indicating learners had positive perceptions of the training and improved awareness of the potential benefits of interactional feedback in computer-mediated communication.
 De multiples approches théoriques soutiennent la notion de rétroaction interactionnelle comme facilitateur du développement d’une langue seconde (L2). Cependant, les recherches démontrent que les apprenants évitent souvent de présenter une rétroaction pendant le travail collaboratif entre pairs, ne profitan ainsi pas des principales possibilités d’apprentissage et de développement des langues. Des études récentes ont examiné comment l’enseignement métacognitif (EM) peut être utilisé pour former explicitement les apprenants à la rétroaction interactionnelle, les résultats montrant une augmentation des cas de rétroaction (Fujii et al., 2016) et une amélioration des résultats en L2 (par exemple, Sato & Loewen, 2018; Sippel, 2019). S’appuyant sur ces travaux, cette étude exploratoire a examiné les effets de l’EM sur l’offre de fonctions interactionnelles dans la communication synchrone par ordinateur aux apprenants d’anglais de niveau intermédiaire L2 (n = 26). En utilisant un modèle de pré-traitement-post-test, tous les apprenants ont accompli trois tâches de consensus décisionnel, les apprenants du groupe de traitement recevant des consignes directes sur les avantages de l’interaction via une vidéo pédagogique, une tâche de pratique et un compte rendu ultérieur pour toute la classe. Le groupe de contrôle a effectué les tâches sans EM. Les résultats montrent que l’apport d’une rétroaction interactionnelle et d’épisodes liés à la langue par les apprenants a augmenté après l’EM, avec des mesures qualitatives indiquant que les apprenants avaient des perceptions positives de la formation et une meilleure sensibilisation aux avantages potentiels de la rétroaction interactionnelle dans la communication par ordinateur.

In this paper three well-known metaheuristic algorithms comprising of Colliding Bodies Optimization, Enhanced Colliding Bodies Optimization, and Particle Swarm Optimization are employed for size and performance optimization of steel plate shear wall systems. Low seismic and high seismic optimal designs of these systems are performed according to the provisions of AISC 360 and AISC 341. In one part of the low seismic example, a moment frame and Steel Plate Shear Wall (SPW) strength are compared. Performance optimization of the Special Plate Shear Wall (SPSW) for size optimized system is one of the objectives of the high seismic example. Finally, base shear sensitivity analysis on optimal high seismic design of SPSW and size optimization of a 6-story to a 12-story SPSW are performed to have a comprehensive view on the optimal design of steel plate shear walls.

This article reviews contemporary North American and international approaches to the design of concrete-filled hollow structural section (HSS) members for flexure, axial compression plus uniaxial bending, tension, and shear. Results from tests on concrete-filled HSS members under flexure and combined loading are compared to predicted strengths using current (CSA S16:19 and AISC 360-16) and recommended CSA S16 design equations (with limits of validity). A first-order reliability analysis of design provisions for flexure is performed in accordance with CSA S408-11, and recommendations are made for potential revision of CSA S16. Design examples are provided, and results are compared to the counterpart American code (AISC 360-16). This paper is Part II of a two-part series. Part I covers materials, cross-section classification, and concentrically loaded columns.

Since the 1990s, structural engineering practice geared toward the use of hollow structural sections (HSS), notably square HSS, for their economy, and ease of design and construction. According to the AISC Seismic Provisions, during a severe earthquake, these braces could undergo post-buckling axial deformations 10 to 20 times their yielding deformation. However, recent experimental studies indicate that braces made of square HSS, depending on their size, width-to-thickness, and slenderness ratio, are vulnerable to fracture even prior to 10. Therefore, relying on past experimental studies comprised of a few square HSS specimens to develop seismic requirements for SCBF with square HSS could lead to underestimation of the seismic risk. This paper aims to evaluate the fracture risk of braces in existing SCBFs designed in accordance with AISC 341-05 and AISC 341-16 through incremental dynamic analyses (IDA) along with experimentally developed regression model that estimates fracture.