American Institute Of Steel Construction Research Articles

Steel column planning using the American Institute of Steel Construction (AISC) 2010 method

The latest SNI rules for steel structure building has been published namely SNI 1729-2015 which refers to the AISC 2010. In AISC 2010, there is a new design method called Direct Analysis Method (DAM) as an alternative to the Effective Length Method (ELM). The aim of the study is to plan steel columns using the AISC 2010 method and calculate and also analyse the steel column capacity. In this study, ETABS computer analysis program that have been whole integrated includes the modelling, analysis and design were used, so as to produce safe and economical modelling, analysis and design. The results of trial and error showed that dimensions for the 1st and 2nd floor columns WF profile, 3rd and 4th floor columns used WF 250x250x9x14 profile, and the 5th floor column used WF 175x175x7.5x11 profile. The load that applied was only dead load and live load. ETABS analysis results obtained output in the column design in the form of axial force (P) 1688,971 kN, moment (Mux) 60,257 kN.m, moment (Muy) 23,009 kN.m. The calculation results of steel column design analysis using DAM method obtained the value of the ratio of the strengths of columns 1st and 2nd floors for 0.42, columns 3rd and 4th floors for 0.33 and the 5th floor for 0.15. The steel column material requirements for each 1st and 2nd floor are 352.66 kg, 2nd and 3rd floors are 271.35 kg, and the 5th floor is 150.75 kg. The design of steel columns by means of DAM results in a higher profile capacity, so that the profile designs used can be more economical.

Optimization and comparison of different standards for compressed welded box columns

Abstract Stability is one of the most critical problems in the design of welded metal structures, since in many cases instability causes failure or collapse of the structures. The present study aims to show the minimum mass design procedure for welded steel box columns loaded by a compression force. The normal stresses and overall stability are calculated for pinned columns. The dimensions of the box columns are optimized by using constraints on global stability, local buckling of webs and flanges. Different design rules and standards are compared: Eurocode 3, Japan Railroad Association, American Petroleum Institute, and American Institute of Steel Construction. The calculations are made for different loadings, column length and steel grades. The yield stress varies between 235 and 690 MPa. Optimization is carried out using the generalized reduced gradient method in Excel solver. Cost calculations and comparisons show the most economical structure.

The effect of weld residual stress on fracture toughness at the intersection of two welding lines of offshore tubular structure

Due to the spatial complexity and fabrication characteristics of offshore platforms, it is inevitable to encounter overlaps or proximity of weld lines in tubular joints. Several international standards such as American Petroleum Institute (API), American Welding Society (AWS), and American Institute of Steel Construction (AISC) regulate the minimum distance between primary weld beads; however, any logical and detailed background of this limitation has not been presented. For a non-compliant weld joint where the regulation is not met, fracture toughness calculation is a typical index to verify the structural integrity.This research consists of two parts. First, weld residual stress distributions are calculated by a 3D thermo-mechanical nonlinear Finite Element Analysis. Two crossing welds, a T-weld crossing on a butt weld, are simulated in one model. A separate tee and a butt welding simulations are also performed for a comparative purpose. Second, SIFs and J-integral values are calculated at the surface and deepest crack tip locations for four different types of semi-elliptical surface cracks. Four cracks are embedded into the weld model and the residual stress distribution from the 3D thermo-mechanical FEA are mapped to a 3D FE crack model as initial conditions. An additional axial tensile load is also imposed. SIF values are compared with those using the weighting function method for the butt weld model subject to three load cases, i.e., tensile stress only, weld residual stress only, and both of them. From the simulation, a tubular joint containing a chord girth weld intersected with weld beads of brace is found to show lower the SIF values than that having only a girth weld on chord.

K-Factor Solution for Combined Braced–Unbraced Offshore Jacket Frames

Abstract Many offshore jackets have no braces between the top of jacket and the bottom of topsides deck. This can be either due to the installation requirement and/or an effort to reduce wave loads. This kind of jacket bay is a portal frame. For the design of portal frame columns, the current offshore standards point to the unbraced frame alignment chart solution from onshore standards such as the American Institute of Steel Construction (AISC). In this paper, we will show that the AISC alignment chart unbraced frame K-factor solution is conservative for offshore applications, and perhaps too conservative. This is because the traditional alignment chart assumes that the entire structure is a moment frame. In offshore applications, the unbraced frame is almost always combined with braced frames from above and/or below. In this paper, we will derive a K-factor solution that is suitable for a braced/unbraced frame combination. This solution is validated with structural buckling finite element method (FEM) analyses of typical offshore frames. Design implications from using the traditional alignment chart versus current new K-factor solution are also discussed.

ÇELİK ÇERÇEVELERİN FARKLI STOKASTİK YÖNTEMLER KULLANILARAK OPTİMUM BOYUTLANDIRILMASI

Bu çalışmada rijit çelik çerçevelerin Av Arama, Parçacık Sürü ve Büyük Patlama - Büyük Çöküş optimizasyon yöntemlerini temel alan üç farklı optimum tasarım algoritması sunulmuştur. Av Arama optimizasyon algoritması kurt, aslan, yunus gibi hayvanların grupça avlanmalarından esinlenilerek geliştirilmiştir. Grupta yer alan hayvanlar (avcılar) avlarını bir daire içine alır ve yakalarlar. Avcılar, kokularının av tarafından hissedilmemesi için rüzgâra doğru durmazlar. Bu avcılardan her birisi yapısal bir optimizasyon problemi için aday bir çözüm oluşturur. Parçacık Sürü optimizasyon algoritması sürü halinde hareket eden kuş, balık ve böceklerden esinlenerek geliştirilmiş bir yöntemdir. Sürüdeki her hayvan (parçacık) kendi konumunu sürüde bulunan diğer parçacıklara ve kendisinin bir önceki konumuna göre düzenler. Hedefe ulaşıncaya kadar bu süreç devam eder. Büyük Patlama – Büyük Çöküş optimizasyon algoritması evrenin büyük patlama ve büyük çöküş hipotezinden esinlenilmiştir. Büyük Patlama evresinde Merkez Noktası ya da Kütle Merkezi olarak adlandırılan benzersiz bir nokta üretilmektedir. Algoritma kapsamında Kütle Merkezi yakınlarında yeni adaylar belirlenir, uygunlukları hesaplanır ve içlerinden en iyisi seçilir. Çalışma kapsamında üç katlı üç açıklıklı, beş katlı üç açıklıklı ve yedi katlı üç açıklıklı olmak üzere üç adet çelik çerçevenin bu algoritmalar ile en küçük ağırlıkları bulunacak şekilde optimum boyutlandırılmaları yapılmıştır. Boyutlandırma yapılırken LRFD-AISC (Yük ve Dayanım Katsayılarıyla Tasarım (YDKT)) yönetmeliğindeki sınırlayıcıların sağlanması hedeflenmiştir. Ayrıca, üç teknik birbiriyle kıyaslanmış, Parçacık Sürü algoritması 2 örnekte en iyi sonucu bulması açısından diğerlerine kıyasla daha iyi bir performans sergilemiş, Av Arama algoritması da onu takip etmiştir. Her örnek için en küçük ağırlığı bulan tekniğin sonuçları baz alınarak çerçevelerin SAP2000 analiz programı ile yük altında deplasman analizleri yapılmıştır. Son olarak, çerçevelerin en üst kat yanal deplasmanları belirlenmiş ve yorumlarda bulunulmuştur.

Inelastic behavior and seismic design of multistory chevron-braced frames with yielding beams

Chevron or inverted V-braced frames offer numerous architectural and structural advantages, but the current special concentrically braced frame (SCBF) seismic-design requirements in the American Institute of Steel Construction (AISC) Seismic Provisions for Structural Steel Buildings lead to deep, heavy chevron beams; as a result, few chevron SCBFs are built today. Recent research on single-story chevron SCBFs demonstrated that beam yielding can be advantageous at higher demand levels, and design for large, inelastic unbalanced brace-force demands may still result in acceptable seismic performance. However, this prior research did not consider the response of multistory frames. In particular, questions remain as to the potential for concentration of damage, the impacts of composite slabs, and the effects of different beam-to-column connections; these issues can only be investigated using multistory frames. A companion research program was conducted to investigate multistory systems with chevron SCBFs using experimental and computational simulation methods. In the first phase of the research, a three-story chevron SCBF designed to permit beam yielding was tested at the National Center for Research on Earthquake Engineering (NCREE) Laboratory in Taipei, Taiwan. The test results were then used to validate a nonlinear, continuum finite-element model. A limited parametric study was conducted to build upon and further the experiments, specifically to evaluate different beam strengths and stiffnesses. These results were combined to develop design recommendations for chevron SCBFs with yielding beams.

Comparative study of the AISC-LRFD, Eurocode 3 & SP 16.13330.2017 steel members design

This paper presents the comparative design procedures for steel frame elements using three different International design codes, viz. the American Institute of Steel Construction (AISC), the European Code (EC3) and the Russian Design Code (SP). It focuses on the resistance capacity of steel members subjected to different loads, such as tension, compression and flexure. It compares the formulation of all codes that identify their similarities and differences. The comparative study is performed for a compact rolled I sections with different slenderness and lateral bracing lengths. The results are presented graphically in different ways such as strength curves, Moment capacity versus lateral bracing length and normalized graphs. The comparative study shows that the resistance capacity specified by all specifications can be different for some considered cases. For compression member, SP specifications have higher capacity and economical approach. For flexural member, AISC gives higher capacity for inelastic region and EC3 gives higher capacities for elastic region but SP approach is lower for flexural capacity.

Experimental study on time-dependent deformation of hybrid steel–PRC girder with headed stud shear connections under sustained loading

In a hybrid girder, the connections at the steel–prestressed reinforced concrete (steel–PRC) junction must be designed to resist steel–concrete interfacial tensile and shear forces. Headed stud shear connections are most commonly and widely used for such an application. In Japan, the Japan Road Association specifies a stud capacity that is 0.12, 0.13, and 0.22 times those of the American Institute of Steel Construction, Japan Society of Civil Engineers, and EURO code specifications, respectively. Hence, in Japan, the existing design method uses less than 50% of the actual nominal shear capacity of connectors. Owing to a low design shear force, the influence of sustained loads has not yet been considered nor studied comprehensively. Moreover, in a hybrid girder, the prediction of the time-dependent deformation behaviour under sustained loading is crucial for ensuring serviceability; however, few studies have focused on this subject. Five scaled-down hybrid steel–PRC girder specimens of a real bridge with headed stud connections were tested under sustained and static loads. The time-dependent deformation behaviour was sensitive to the exposure time, previous loading history, prestress level, concrete strength, and creep and shrinkage phenomena. The results of this study provide an important basis and reference data for designing such girders while considering their long-term response with time effects.

An Investigation on Base Metal Block Shear Strength of Ferritic Stainless Steel Welded Connection

This study develops a finite element analysis model to predict the ultimate strength of the base metal block shear fracture based on previous experimental results and compares the experimental results with the analysis results to verify the effectiveness of the analysis model. This study also analyzed additional variables of the welding direction and weld length on the applied load to investigate the structural behaviors and fracture conditions. In addition, predicted strength according to the analysis results were compared with those by the current design equations, and the equations proposed by previous researchers. As a result, the design formula by the current design equations, such as Korea Building Code (KBC)/American Institute of Steel Construction (AISC) and European Code (EC3), and the equations proposed by Oosterhof and Driver underestimated the base metal block shear strength of ferritic stainless steel by up to 42%. Equations suggested by Topkaya and Lee et al. for carbon steel and austenitic stainless steel welded connections provided more accurate strength predictions, while they did not reflect the difference of material properties. Therefore, this study proposed a modified strength equation for ferritic stainless steel welded connection with base metal block shear fracture considering the stress triaxiality effect of the welded connection and the material properties of ferritic stainless steel.

Numerical Study on the Deformation Behavior of Longitudinal Plate-to-High-Strength Circular Hollow-Section X-Joints under Axial Load

This study aims to investigate the joint strength of longitudinal plate-to-high-strength steel circular hollow-section X-type joints under plate axial load. The material properties of high-strength steel with nominal yield strengths of 460, 650, 900, and 1100 MPa were used for parametric analysis. The variables for analysis were ratios of chord diameter to thickness, plate width to chord diameter, and utilization. To determine the capacity of connections, the joint strengths using a deformation limit and a strength limit were considered and compared with American Institute of Steel Construction (AISC), Eurocode 3, and ISO 14346. The joint strength determined by the ultimate deformation limit is approximately equal to the joint strength determined by the strength limit state at the yield strength of 460 MPa. The difference between both the joint strengths, however, becomes higher with increasing yield strength. The design equations estimate the joint strength based on the ultimate deformation limit approximately until the limitation of the nominal yield strength in each design code. As the nominal yield strength increases, the joint strengths are overestimated. In using high-strength steel in circular hollow-section X-type joints, the reduction factors of 0.75 and 0.62 for AISC and ISO 14346 are suggested for the nominal yield strengths of 900 and 1100 MPa, respectively. In Eurocode 3, the reduction factor of 0.67 is also suggested for a yield strength of 1100 MPa.

Determination of Optimal Configuration for Mega Bracing Systems in Steel Frames using Genetic Algorithm

Mega bracing is one of the recently emphasized methods for lateral bracing of structures. In the present study, various configurations of mega bracing systems in terms of installation angle for lateral bracing of steel structures are evaluated and optimized. The investigated frames are designed and optimized using genetic algorithm (GA) according to LRFD-AISC (load and resistance factor design, american institute of steel construction). Frame analysis is carried out by means of finite element method, while optimization is conducted using GA considering three different types of selection and crossover, simultaneously. The results demonstrate that the optimum angle of mega bracing in steel frames is within the range of 36° to 42° with regard to the frame height and span. Furthermore, with increase in frame height, the employment of optimally distributed mega braces along the height of the frame results in reduction of story drifts and also the frame weight. Additionally, simultaneous utilization of various selection and crossover types in GA optimization leads to an increase in convergence rate of optimum weight of the frame as well as reduction in the required computations.

Probabilistic Assessment of Seismic Force Demands in Biaxially Loaded Columns in Chevron-Configured Special Concentrically Braced Frames

Special concentrically braced frame (SCBF) columns are designed as force-controlled elements and are intended to respond elastically during moderate-to-high return-period events. When placed at the intersection of orthogonal chevron-configured braced frames with fixed beam-column connections, SCBF columns are subjected to biaxial loading, including flexural demands developed in the beams due to unbalanced tension-compression brace forces. A probabilistic assessment of the force demands in biaxially and uniaxially loaded columns in chevron-configured SCBF is presented herein. Nonlinear response history analyses are performed on three-dimensional models of 3-, 9- and 20-story SCBFs, and statistical descriptions of the results are used to investigate (1) the force demands relative to the capacity-design-based and elastic designs suggested by the American Institute of Steel Construction (AISC) Seismic Provisions, (2) the implications of the flexural demands transmitted to columns (via braced frame beams), and (3) the combinatorial effects of demands in biaxially loaded columns generated by orthogonal ground-motion components. At the maximum considered earthquake (MCE) hazard level, the median axial force demands in the biaxially loaded first-story columns of the three-story building are approximately at the level corresponding to the expected brace strength and exceed the design forces amplified by the overstrength factor. Axial flexure interaction is especially significant in the biaxially loaded columns of all three building cases. The results also show that the combinatorial effect of axial forces transmitted to the biaxially loaded columns via the orthogonal braces is generally lower in taller buildings and also depends on the demand level.

PERIODIC BOLT PLACEMENT IN STEEL STRUCTURES FOR GUIDED DAMAGE DETECTION

Connections form the weakest link in structural systems. Bolted connections are especially susceptible to stress corrosion cracking due to stress-riser points at the bolt edges and the intrusion of water between plates leading to galvanic corrosion. Bolts are conventionally placed based on minimum and maximum spacing requirements guided by American Institute of Steel Construction. Unfortunately, the detectability of crack and corrosion is currently not a design variable. In this study, bolts are placed in periodic pattern such that they exhibit unique frequency response. The periodic placement allows modeling only unit cell in the shape of hexagon with periodic boundary conditions to obtain the frequency response. When damage occurs, the periodic pattern is broken, and the frequency response behavior changes. The influence of crack to vibration modes is numerically modeled, and the damage detection ability with unique bolt placement is demonstrated. It is shown that the spatial distribution of bolt can assist the damage detection ability, which should be considered as a criterion in the design of bolted connections.

Application of the Project Management Body of Knowledge (PMBOK) in an Interdisciplinary Capstone: The AISC Steel Bridge Competition

Seven West Point Cadets recently competed in the American Institute of Steel Construction (AISC) Steel Bridge Competition for their capstone project. West Point capstones allow cadets to demonstrate their practical, innovative, and hands-on solutions to complex problems, serving as an opportunity to demonstrate characteristics required of Army leaders. For purposes of meeting guidelines established by the Accreditation Board for Engineering and Technology (ABET), the capstone serves as a culminating major engineering design experience in at least two civil engineering contexts. It incorporates engineering standards and allows students to apply knowledge and skills from previous coursework. Historically consisting of all civil engineers, this year’s interdisciplinary Steel Bridge Team included a systems engineer major for the purposes of improved project management. As tomorrow’s leaders are asked to solve complex problems and win in an uncertain tomorrow, the need for graduates to have the skills required to organize chaos, manage risk, establish a schedule and plan, and adapt to change are more important than ever. This paper, organized by the Project Management Body of Knowledge (PMBOK) Process Groups of Initiating, Planning, Executing, Monitoring and Controlling, and Closing, documents the implementation of project management principles towards the West Point Steel Bridge Team’s success and their development as future leaders.

Fillet welds around circular hollow sections

An experimental and numerical research program was conducted to evaluate the safety of North American design rules for fillet welds around the perimeter of steel circular hollow sections (CHS). This assessment was performed in the context of the current American Institute of Steel Construction (AISC) steel building specification, AISC 360. Specifically, the appropriateness of the fillet weld directional strength-enhancement factor in AISC 360-16 Clause J2.4b was investigated for fillet welds to CHS branches, and the effect of non-uniform connection flexibility on the strength of welds in CHS-to-CHS connections was studied. A total of 24 large-scale, weld-critical experiments were tested, and a further 290 non-linear finite element models were used to parametrically expand the database. It was found that if the directional-strength factor is used, the target reliability (or safety) index prescribed by AISC for connectors, even when the welds are fully effective, is not achieved; hence, a recommendation to prohibit this factor for all fillet welds around the perimeter of CHS is made. With this restriction, it is then shown that AISC 360-16 Clause J2.4a fillet weld design provisions meet AISC’s target safety index for welds in CHS-to-CHS X-connections, where a weld effective length phenomenon exists. It is therefore recommended that AISC advocate 100% weld effective lengths for fillet welds in CHS-to-CHS X-connections, provided that the directional strength-enhancement factor (1.0 + 0.5sin1.5θ) is not used.

Experimental and numerical studies on the vibration serviceability of fanshaped prestressed concrete floor

An extensive experimental and numerical research was undertaken to study the vibration serviceability of a long-span fanshaped prestressed concrete floor system to be used in the lounge of a major airport. Specifically heel-drop and jumping impact tests were conducted to obtain the natural frequencies and modal damping ratios of the floor system, followed by the discussion on the distribution of peak accelerations. Running tests and simulation were also performed to capture the acceleration responses. Moreover, the finite element method was used to evaluate the dynamic characteristics. The floor system is found to have a low fundamental frequency (≈6.00 Hz) and the corresponding modal damping ratio (average ≈2.20%). The comparison of the experimental results with the published American institute of steel construction (AISC) design guide indicates that the prestressed concrete floor system exhibits satisfactory vibration perceptibility overall. The study results also show that the intensity and the location of impact excitation have a significant influence on the rate of acceleration decay. A crest factor βrp is proposed based on the test results to calculate the maximum root mean square acceleration for running for convenience.

School based optimization algorithm for design of steel frames

In this paper, a school-based optimization (SBO) algorithm is applied to the design of steel frames. The objective is to minimize total weight of steel frames subjected to both strength and displacement requirements specified by the American Institute of Steel Construction (AISC) Load Resistance Factor Design (LRFD). SBO is a metaheuristic optimization algorithm inspired by the traditional educational process that operates within a multi-classroom school. SBO is a collaborative optimization strategy, which allows for extensive exploration of the search space and results in high-quality solutions. To investigate the efficiency of SBO algorithm, several popular benchmark frame examples are optimized and the designs are compared to other optimization methods in the literature. Results indicate that SBO can develop superior low-weight frame designs when compared to other optimization methods and improves computational efficiency in solving discrete variable structural optimization problems.

Optimum Design of Braced Steel Space Frames Using Teaching Learning Based Optimization

In this study, optimum design of braced steel space frames is obtained via a novel metaheuristic method, teaching learning based optimization. This algorithm method consists of the two basic phases. The first phase is called as teaching; In this phase, the knowledge interaction occurs between students and teacher. In the second phase, learning phase, the knowledge interaction occurs among students in the class. Optimum profiles are selected among 128 W taken from American Institute of Steel Construction (AISC). The constraints imposed on the frame example are stress constraints as stated in AISC-ASD specifications, geometric constraints and displacement constraints. To obtain optimum solutions, a program is coded in MATLAB programming to incorporate with SAP2000 - Open Application Programming Interface (OAPI). The results are compared through tables and figures. The results indicate that teaching learning based optimization method and MATLAB SAP2000 OAPI technique are applicable even for complex problems and present practical solutions.

Seismic Performance Evaluation of Steel Ordinary Moment Frames

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.

Buckling of Conventional and High-Strength Vanadium Steel Double-Angle Compression Members: Computational Parametric Study

High-strength, low-alloy vanadium (HSLA-V) steel offers higher strength and toughness than conventional steel. The resulting lighter weight and more slender structural components are more susceptible to buckling in compression. A series of conventional Grade 50 steel and HSLA-V (nominal Grade 80) steel angle compression components was tested at Lehigh University’s ATLSS laboratory. This experimental database was used to develop and verify a modeling approach using the general purpose finite element (FE) software ABAQUS to simulate the component buckling response. This study extensively evaluates the 2010 American Institute of Steel Construction (AISC) and Steel Joist Institute (SJI) design equations for double-angle buckling, resulting in significant findings and recommendations for both specifications. The primary objective of this paper was to assess the validity of applying the buckling equations given in the SJI 2010 Design Specification for long-span and deep-long-span joists (SJI, 2010) to double-angle compression members manufactured using 80-ksi HSLA-V steel. Present SJI specifications are applicable only for steel with specified yield stress of 50 ksi or less. Another objective of this study was to compare the design equations for compression buckling in the SJI Design Specification and the AISC 2010 Specification (AISC, 2010) and to develop recommendations for enhancing the accuracy of buckling equations commonly used in current practice. To achieve these goals, an extensive database of analytical buckling simulations was created to compare the performance of the code buckling equations in determining the buckling strength for regular and HSLA-V steel compression members. Potential solutions for resolving the observed lack of conservatism in the strong-axis buckling predictions were investigated. The use of the modified component slenderness ratio in the AISC provisions significantly improved the accuracy of the SJI buckling strength predictions for strong-axis buckling cases with Q-factor values less than 1.0.