Progressive collapse behavior of joints in steel moment frames involving reduced beam section

2020 ◽  
Vol 225 ◽  
pp. 111297
Author(s):  
Canwen Chen ◽  
Huiyun Qiao ◽  
Jinpeng Wang ◽  
Yu Chen
Keyword(s):  
Progressive Collapse ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Reduced Beam Section ◽  
Beam Section ◽  
Collapse Behavior

Design Approach To Bolted End-Plate Vertical-Slits RWS Connection

2021 ◽  
Author(s):  
Hamidreza Nazaralizadeh ◽  
Hamid Ronagh ◽  
Parham Memarzadeh ◽  
Farhad Behnamfar
Keyword(s):  
Numerical Models ◽  
Design Procedure ◽  
Cost Effective ◽  
Design Parameters ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Reduced Beam Section ◽  
End Plate ◽  
Beam Section ◽  
Rbs Connections

Abstract Extensive research has been carried out on steel moment frames to improve the cyclic performance of seismic resisting connections with reduced beam section (RBS). The RBS connections are conventionally known by the radial reduction of the beam flange. Where the contribution of the beam flange to the flexural resistance is greater than that of the beam web, some researchers have proposed reduced web section (RWS) connections, instead. The present study dedicates to the RWS connections with vertical-slits (VS), as a cost-effective alternative with multiple design parameters. This paper aims to obtain proper ranges for the geometric design parameters of the VS-RWS connection. In this order, two full-scale specimens of the bolted end-plate VS-RWS connection were experimentally tested under the SAC cyclic loading to evaluate the performance of connections, and then a parametric study was carried out using the verified numerical models. The parameters consist of the distance between the column face and the beginning of the reduced region, the length of the reduced region, as well as the depth and width of the vertical-slits. Based on the results, certain recommendations for the ranges of the geometric parameters of VS-RWS have been suggested. In order to obtain the story drift of the frame caused by the VS-RWS beam flexural deformation using the conjugate beam method, the original VS-RWS was replaced with an equivalent constant-cut reduced beam section (CC-RBS). At last, a simple design procedure for VS-RWS connections was provided according to AISC-358.

Design by Qualification Testing of Reduced Beam Section Welded Connections

2015 ◽  
Vol 1111 ◽  
pp. 229-234
Author(s):  
Florea Dinu ◽  
Dan Dubină ◽  
Cristian Vulcu ◽  
Calin Neagu
Keyword(s):  
Numerical Models ◽  
Shear Stresses ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Reduced Beam Section ◽  
The Face ◽  
Qualification Testing ◽  
Low Stiffness ◽  
Beam Section ◽  
Seismic Applications

Steel moment frames are common systems in multi-storey buildings. Even the relatively low stiffness of the system limits the applicability, they remain popular in seismic applications due to the good dissipation capacity. Considered deemed-to-comply in seismic applications, welded beam to column connections experienced serious damages and even failures during strong seismic earthquakes. These failures included fractures of the beam flange-to-column flange groove welds, cracks in beam flanges, and cracks through the column section. To reduce the risk of brittle failure of welded connections, beam weakening near the ends became popular. To assure the desired behavior, i.e. the development of plastic deformations in the reduced beam section zones rather than at the face of the column, proper detailing and sizing is necessary. Today design provisions are limited to long beams, where the effect of shear stresses may be neglected. The application of the same rules for short beams might be non-conservative, and therefore qualification testing is necessary. The study presents the qualification testing of reduced beam sections welded connections of short beams. Both monotonic and cyclic tests were performed and numerical models were validated based on the test data.

scholarly journals Analysis of Fracture Behavior of Large Steel Beam-Column Connections

2018 ◽  
Author(s):  
Roberto Leon ◽  
Liangjie Qi ◽  
Jonathan Paquette ◽  
Matthew Eatherton ◽  
Teodora Bogdan ◽  
...  
Keyword(s):  
Scale Effects ◽  
Tall Buildings ◽  
The United States ◽  
Steel Beam ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Stress Concentrations ◽  
Reduced Beam Section ◽  
Design Qualification ◽  
Beam Section

Recently completed experimental steel beam-column connection tests on the largest specimens of reduced-beam section specimens ever tested have shown that such connections can meet current seismic design qualification protocols, allowing to further extend the current AISC Seismic Provisions and the AISC Provisions for Prequalified Connections for Special and Intermediate Steel Moment Frames. However, the results indicate that geometrical and material effects need to be carefully considered when designing welded connections between very heavy shapes. Understanding of this behavior will ease the use of heavier structural shapes in seismic active areas of the United States, extending the use of heavy steel sections beyond their current use in ultra-tall buildings. To better interpret the experimental test results, extensive detailed finite element analyses are being conducted on the entire series of tests, which comprised four specimens with beams of four very different sizes. The analyses intend to clarify what scale effects, at both the material and geometric level, influence the performance of these connections. The emphasis is on modeling of the connection to understand the balance in deformation between the column panel zones and the reduced beam section, the stress concentrations near the welds, the effects of initial imperfections and residual stresses and the validity of several damage accumulation models. The models developed so far for all four specimens have been able to accurately reproduce the overall load-deformation and moment-rotation time histories.  

Evaluation of Dynamic Collapse Behavior of Steel Moment Frames Damaged by Blast

2011 ◽  
Vol 82 ◽  
pp. 404-409
Author(s):  
Kyung Koo Lee ◽  
Lan Chung ◽  
Sang Hyun Lee ◽  
Tae Won Park ◽  
Jieun Rho
Keyword(s):  
Progressive Collapse ◽  
Mitigation Strategies ◽  
Analysis Method ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Strain Rate Effects ◽  
Collapse Analysis ◽  
Alternate Path Method ◽  
Collapse Behavior ◽  
Progressive Collapse Analysis

Blast effects on structures and blast mitigation strategies have been vigorously studied in the world. The alternate path method, or common progressive collapse analysis method, of structures assumes the threat-independent removal of vertical load-carrying elements. However, in reality, a blast-induced column-missing event will produce the damage on adjacent structural elements and the rapid dynamic response of the structures. In this study, the strain rate effects on the dynamic collapse behavior of steel moment frames are investigated by performing the blast-induced sequential progressive collapse analysis. Then, the improvement of the progressive collapse analysis method is discussed based on the numerical results.

scholarly journals INVESTIGATION OF BEHAVIOR OF INTERIOR STEEL CONNECTIONS WITH OPENINGS IN BEAM WEB AND FLANGE UNDER MONOTONIC LOADING

2021 ◽  
Keyword(s):  
Plastic Hinge ◽  
Local Buckling ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Reduced Beam Section ◽  
Steel Connections ◽  
Finite Element Software ◽  
Expected Performance ◽  
Rigid Connection ◽  
Beam Section

Connections are considered to be one of the most prominent components of steel moment frames and have received studious attention in recent years. The core problem of welded connections is premature brittle fracture of weld in the critical beam-to-column connection region. Within the framework of this issue, various approaches have been proposed to solve the mentioned problem. Intentional weakening of the beam web or flange is in line with the purpose of leading the plastic hinge away from the column face, hence, increasing the ductility. The aim of this research is to investigate the behavior of interior connections subjected to monotonic lateral loading in case of presence of openings in beam web or flange. To do so, an ordinary fully welded rigid connection, reduced beam section, reduced web section, and drilled flange connection models are simulated numerically, utilizing finite element software, ANSYS. The results indicate that scrupulous selection of opening sizes are of great importance to fulfill the desired outcome which is avoiding the brittle failure of connections. Furthermore, the use of drilled flange, reduced beam section, or reduced web section connections satisfy the expected performance and it is proposed to use them according to practicability, architectural and economic considerations as well as site conditions. Shear deformation and local buckling is observed in reduced web section connections while in drilled flange connections, stress concentration around the opening is critical.

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