Cyclic performance of existing moment connections in steel retrofitted with a reduced beam section and bottom flange reinforcements

2007 ◽  
Vol 34 (2) ◽  
pp. 199-209 ◽  
Author(s):  
Sang-Hoon Oh ◽  
Young-Ju Kim ◽  
Tae-Sup Moon
Keyword(s):  
Plastic Hinge ◽  
Composite Beams ◽  
Bottom Flange ◽  
Deformation Capacity ◽  
Moment Connections ◽  
Element Analysis ◽  
Reduced Beam Section ◽  
Steel Shape ◽  
The Face ◽  
Beam Section

This study investigated the effectiveness of retrofit methods in improving the deformation capacity of existing moment connections in composite beams. Nonlinear finite element analysis was also performed to identify the cause of the connection failure prior to testing. Tests included one conventional specimen and four retrofit specimens. Three retrofit methods were introduced: a reduced beam section (RBS) only, an RBS with bottom flange reinforcement (RBR), and an RBS-shaped bottom flange reinforcement (RSR). A composite beam performs differently than a bare steel shape because the concrete compression flange greatly increases the tensile demands on an unreinforced bottom flange. Therefore, these retrofit methods were applied only to the bottom flanges of the beam. Quasi-static loading tests were performed. The main conclusions were as follows: (i) the deformation capacity of the existing moment connections in composite beams is not sufficiently improved by RBS alone; and (ii) both the RBR and RSR details move the plastic hinge away from the face of the column and reduce stress levels in the vicinity of the beam bottom flanges, sufficiently improving the deformation capacity.Key words: composite construction, seismic performance, reduced beam section (RBS), flange reinforcement, ductility, deformation capacity.

scholarly journals RBS moment connection analysis using a solid model

2021 ◽  
Author(s):  
Mikaela Coello-Mena
Keyword(s):  
Seismic Event ◽  
Plastic Hinge ◽  
Efficient Design ◽  
Moment Connections ◽  
Reduced Beam Section ◽  
Moment Connection ◽  
Steel Moment Connection ◽  
Cutting Out ◽  
Beam Section ◽  
Rbs Connections

The unpredictability of the steel beam welding connection has led to many solutions, including the are of focus for this research Reduced Beam Section ( Moment Connections The RBS in steel moment connection facilitates the calculation and predictability of failure in design The RBS section is created by cutting out part of the flanges in a beam This creates a plastic hinge where the beam will fail first 1 This creates a model of predictability on the durability and strength of the beams Creating a RBS connection increases the overall ductility of the steel frame The RBS section reduces the flange width which causes stress concentration on the reduced section and this then lowers the stress on the welds. The lower stress then prevents unexpected brittle fracture in the welding a predicted plastic deformation of the RBS section during a seismic event 2 3 The research is focused on optimizing the RBS connection Finite models will be created using ANSYS to investigate how different RBS connections react in different situations and what is the most efficient design in terms of safety and cost.

scholarly journals Cyclic Behavior of Steel Beam-to-Column Moment Connections Using Different Sizes of Flange Plates and Reinforced by a Single Rib Plate

2018 ◽  
Vol 4 (1) ◽  
pp. 138
Author(s):  
Abbas Haghollahi ◽  
Hassan Ahmadi
Keyword(s):  
Numerical Study ◽  
Plastic Hinge ◽  
Equivalent Plastic Strain ◽  
Cyclic Behavior ◽  
Bottom Flange ◽  
Moment Frames ◽  
Moment Connections ◽  
Element Analysis ◽  
Beam Geometry ◽  
Special Moment Frames

This paper presents a numerical study on the behavior of connection between steel I-beam and H-column when are affected by cyclic loading. The connection used the flange plates to connect the beam flanges to the column flange. They were welded to the top and bottom flange plates and created a welded flange plate (WFP) connection. Specimens were six models of WFP connections with different beam geometry and flange plate sizes which were modeled and their cyclic behavior were investigated using finite element analysis in ABAQUS program. Three of them were reinforced by a vertical triangular top and bottom rib plates, and others remained unreinforced. The results showed that reinforcement with a vertical triangular rib plate attached to the top and bottom flange plates can improve cyclic behavior of WFP connections.  By using a rib plate, the equivalent plastic strain was increased and showed better plastic hinge formation compared to those with no vertical rib plate. Those models with IPB beam sections had the best cyclic behavior compared to those with IPE beam sections and satisfied the acceptance criteria of AISC seismic provisions for intermediate and special moment frames. We concluded that those WFP connections which did not satisfy the criteria of AISC seismic provisions for special moment frames, can be upgraded by a vertical triangular rib plate in order to be used in special moment frames.

scholarly journals RBS moment connection analysis using a solid model

2021 ◽  
Author(s):  
Mikaela Coello-Mena
Keyword(s):  
Seismic Event ◽  
Plastic Hinge ◽  
Efficient Design ◽  
Moment Connections ◽  
Reduced Beam Section ◽  
Moment Connection ◽  
Steel Moment Connection ◽  
Cutting Out ◽  
Beam Section ◽  
Rbs Connections

The unpredictability of the steel beam welding connection has led to many solutions, including the are of focus for this research Reduced Beam Section ( Moment Connections The RBS in steel moment connection facilitates the calculation and predictability of failure in design The RBS section is created by cutting out part of the flanges in a beam This creates a plastic hinge where the beam will fail first 1 This creates a model of predictability on the durability and strength of the beams Creating a RBS connection increases the overall ductility of the steel frame The RBS section reduces the flange width which causes stress concentration on the reduced section and this then lowers the stress on the welds. The lower stress then prevents unexpected brittle fracture in the welding a predicted plastic deformation of the RBS section during a seismic event 2 3 The research is focused on optimizing the RBS connection Finite models will be created using ANSYS to investigate how different RBS connections react in different situations and what is the most efficient design in terms of safety and cost.

EVALUATION OF PERFORMANCE OF BEAM COLUMN JOINT WITH REDUCED BEAM SECTION

2020 ◽  
Vol 9 (7) ◽  
pp. 1-10
Keyword(s):  
Cross Section ◽  
Progressive Collapse ◽  
Plastic Hinge ◽  
Beam Theory ◽  
Steel Structures ◽  
Element Analysis ◽  
Modeling And Analysis ◽  
Reduced Beam Section ◽  
Weak Beam ◽  
Beam Section

This study reviews mainly holistic design of PEB structure and comparison of behavior of reduced beam section at beam column sub assemblage. Commercial software based on finite element analysis is used for carrying out mathematical modeling and analysis. In recent construction work it is observed that during conditions like earthquake or cyclone connections fails resulting in to progressive collapse. Also it damages column resulting in failure of strong column weak beam theory. In present work after identifying problem structure is fused at connection by reducing beam cross section at location of connection. This is done by reducing cross section of beam in plan expected to result in shifting of plastic hinge from face of column. Reduced beam sections capacity is calculated by simple calculations and verifying them with moment curvature relationships at desired locations. This will concentrate on failure of fuse and not of connection during load application. Motivation of this study is to improve connection by fulfilling strong column and weak beam theory. This will motivate construction industry to utilize steel structures more often assuring repairing of structure as element failure will be dominant over failure of entire structure

scholarly journals Reduced Beam Section (RBS) Moment Connections-Analytical Investigation Using Finite Element Method

2018 ◽  
Vol 4 (6) ◽  
pp. 1240 ◽  
Author(s):  
Christos Sofias ◽  
Dimitra Tzourmakliotou
Keyword(s):  
Cross Sections ◽  
Computational Cost ◽  
Analytical Investigation ◽  
Moment Connections ◽  
Reduced Beam Section ◽  
Moment Resisting ◽  
Group A ◽  
Beam Section ◽  
Structural Parts ◽  
Group B

Reduced Beam Section (RBS) moment resisting connections are among the most economical and practical rigid steel connections developed in the aftermath of the 1994 Northridge and the 1995 Kobe earthquakes. Although the RBS connection effectiveness was widely investigated using US design and construction practices, only limited data exist from European research. Recommendations of RBS applications in steel frames were prescribed in EC8, Part3. However the reliability of these recommendations is under consideration due to above mentioned poor existing data. This paper examines numerous different contours of radius cut-out (Group A) and provides recommendations for the design and detailing of radius cut Reduced Beam Section (RBS) moment connections.  Furthermore, it examines and compares different beam cross sections of European steel profiles (Group B) while the sizing of the RBS cut is kept at a constant ratio. Analytical approach was conducted investigating the adopted by EC8, Part 3 key parameters for the design. The main objective of the applied RBS geometry is to protect the connection and its components (endplate, column flange, bolts, welds) from either plastification or failure. Although the computational cost for optimization with ABAQUS is very large, the results of this study ensures on one hand that the performances of the structural parts can be effectively improved by shape optimization and an the other hand that adjustment in the geometry of the radius cut is needed for safe application to European profiles.

Fragility Assessment of Reduced Beam Section Moment Connections

2010 ◽  
Vol 136 (9) ◽  
pp. 1140-1150 ◽  
Author(s):  
Dimitrios G. Lignos ◽  
Dimitrios Kolios ◽  
Eduardo Miranda
Keyword(s):  
Moment Connections ◽  
Reduced Beam Section ◽  
Beam Section
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