scholarly journals Bidirectional Response of Weak-Axis End-plate Moment Connections: Numerical Approach

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 964
Author(s):  
Eduardo Nuñez ◽  
Guillermo Parraguez ◽  
Ricardo Herrera
Keyword(s):  
Brittle Failure ◽  
Numerical Models ◽  
Failure Mechanisms ◽  
Numerical Approach ◽  
Axial Loads ◽  
Moment Connections ◽  
Design Procedures ◽  
Moment Resisting ◽  
Ductile Behavior ◽  
Partially Restrained

Brittle failure mechanisms can affect the seismic performance of structures composed of intersecting moment resisting frames, if the biaxial effects are not considered. In this research, the bidirectional cyclic response of H-columns with weak-axis moment connections was studied using numerical models. Several configurations of joints with bidirectional effects and variable axial loads were studied using the finite element method (FEM) in ANSYS v17.2 software. The results obtained showed a ductile behavior when cyclic loads are applied. No evidence of brittle failure mechanisms in the studied joint configurations was observed, in line with the design philosophy established in current seismic provisions. However, beams connected to the column minor axis reached a partially restrained behavior. Joints with four beams connected to the column exhibited a partially restrained behavior for all axial load levels. An equivalent force displacement method was used to compare the hysteretic response of 2D and 3D joints, obtaining higher deformations in 3D joints with respect to 2D joints with a similar number of connected beams. Consequently, design procedures are not capable of capturing the 3D deformation phenomenon.

Fracture Moment Strength of Reduced Beam Section with Bolted Web Connections

2007 ◽  
Vol 348-349 ◽  
pp. 717-720
Author(s):  
Ki Hoon Moon ◽  
Sang Whan Han ◽  
Ji Eun Jung
Keyword(s):  
Moment Connections ◽  
Moment Capacity ◽  
Design Procedures ◽  
Reduced Beam Section ◽  
Moment Resisting ◽  
Current Design ◽  
Beam Section ◽  
The Moment ◽  
Rbs Connections ◽  
Experimental Researches

Reduced Beam Section (RBS) moment connections are developed for Special Moment Resisting Frames (SMRF). According to the beam web attachment the column flange RBS connections are classified into Reduced Beam Section with Bolted web connections (RBS-B), and the Reduced Beam Section with Welded web connections (RBS-W). Beam flanges are welded to the column. Regardless of different web attachment details in RBS-B and RBS-W connections current design procedures (FEMA 350) assumes that they could develop plastic moment of the beam gross section. In current design procedures, RBS-B connections should provide the sufficient strength that can reach the plastic moment capacity of the connected beam. However, some experimental researches reported that the beams in RBS-B connections fractured before the connection reached its plastic moment capacity. Such undesirable fracture shows that RBS-B connections have less strength than RBS-W connections. And if RBS-B connections designed in current design procedures, it might fail in a brittle manner and not satisfy SMRF due to undesirable fracture. Thus, this study develops a new set of equations for accurately computing the moment strength of RBS-B connections. The proposed strength equation accurately predicts connection moment capacity for RBS-B connections.

Effects of Different Bolted Connection Types on Seismic Performance of Column-Tree Steel Moment Connections

2013 ◽  
Vol 753-755 ◽  
pp. 581-584
Author(s):  
Kang Min Lee ◽  
Keun Yeong Oh ◽  
Liu Yi Chen ◽  
Rui Li
Keyword(s):  
Seismic Performance ◽  
Bottom Flange ◽  
Moment Connections ◽  
Bolted Connection ◽  
Drift Ratio ◽  
Hole Area ◽  
Story Drift ◽  
Moment Resisting ◽  
Scale Test ◽  
Ductile Behavior

This paper experimentally presents the effects of different bolted connection types on the seismic performance of column-tree steel moment connections used in moment resisting frames. Two full scale test specimens were fabricated and tested: one specimen with slip critical bolted beam splices and the other one with bearing type bolted beam splices. The bearing type splice specimen was expected an improved deformation capacity by means of bolt slippage. The experimental results showed that the slip critical splice specimen successfully developed ductile behavior without brittle fracture until 5% story drift ratio, however for the bearing type splice specimen, the beam bottom flange fractured at 4.0% story drift ratio due to stress concentration around the weld access hole area. However the energy dissipation capacity of the bearing type splice specimen was better than that of the slip critical splice specimen until 4.0% story drift ratio.

Seismic Behavior of Dual Systems with Column Hinging

2001 ◽  
Vol 17 (4) ◽  
pp. 657-677 ◽  
Author(s):  
Mário S. Lopes ◽  
Rita Bento
Keyword(s):  
Ground Motions ◽  
Nonlinear Dynamic Analysis ◽  
Capacity Design ◽  
Dual Systems ◽  
Structural Walls ◽  
Design Procedures ◽  
Earthquake Ground Motions ◽  
Codes Of Practice ◽  
Moment Resisting ◽  
Ductile Behavior

In order that moment-resisting frames exhibit adequate ductile behavior under seismic actions, it is necessary that inelastic deformations spread throughout the height of the frames. It is widely accepted that this is only possible if vertical members remain essentially elastic, such as enforced in the most advanced codes of practice. The results of nonlinear dynamic analysis shown in this work demonstrate that this is not the case if frames resist earthquake ground motions together with structural walls. This was attributed to the fact that these elements prevent the development of sidesway mechanisms even if plastic hinges form at all column extremities at a given floor. As a consequence, it is proposed to relax the capacity design procedures for design of ductile frames that resist earthquake ground motions together with structural walls.

Seismic Risk Mitigation of Historical Masonry Towers by Means of Prestressing Devices

2010 ◽  
Vol 133-134 ◽  
pp. 843-848 ◽  
Author(s):  
Adolfo Preciado Quiroz ◽  
Silvio T. Sperbeck ◽  
Harald Budelmann ◽  
Gianni Bartoli ◽  
Elham Bazrafshan
Keyword(s):  
Seismic Risk ◽  
Seismic Vulnerability ◽  
Risk Mitigation ◽  
Numerical Models ◽  
Failure Mechanisms ◽  
Masonry Towers ◽  
Seismic Risk Mitigation ◽  
Historical Masonry ◽  
Observed Damage ◽  
And Behavior

This work presents the investigation of the efficiency of different prestressing devices as a rehabilitation measure for the seismic risk mitigation of historical masonry towers. As a first phase, the seismic vulnerability of theoretical masonry towers was assessed by means of numerical models validated with information from the literature, observed damage and behavior of these structures due to passed earthquakes (crack pattern and failure mechanisms), and mainly taking into account the engineering experience. Afterwards, the validated models were rehabilitated with different prestressing devices; analyzing the results and concluding which device or the combination of them improved in a better way the seismic performance of the masonry towers. Finally, the methodology will be applied in two historical masonry towers located in seismic areas; the medieval tower “Torre Grossa” of San Gimignano, Italy, and one of the bell towers of the Cathedral of Colima, Mexico.

Analysis and Modeling of Defects in Unsupported Overhanging Features in Micro-Stereolithography

2016 ◽  
Author(s):  
Vito Basile ◽  
Francesco Modica ◽  
Irene Fassi
Keyword(s):  
Finite Element ◽  
Numerical Models ◽  
Numerical Approach ◽  
Fe Analysis ◽  
Test Cases ◽  
Layer By Layer ◽  
Failure Condition ◽  
Micro Scale ◽  
Part Geometry ◽  
Shape Component

In the present paper, a numerical approach to model the layer-by-layer construction of cured material during the Additive Manufacturing (AM) process is proposed. The method is developed by a recursive mechanical finite element (FE) analysis and takes into account forces and pressures acting on the cured material during the process, in order to simulate the behavior and investigate the failure condition sources, which lead to defects in the final part geometry. The study is focused on the evaluation of the process capability Stereolithography (SLA), to build parts with challenging features in meso-micro scale without supports. Two test cases, a cantilever part and a bridge shape component, have been considered in order to evaluate the potentiality of the approach. Numerical models have been tuned by experimental test. The simulations are validated considering two test cases and briefly compared to the printed samples. Results show the potential of the approach adopted but also the difficulties on simulation settings.

An innovative detail for precast concrete beam–column moment connections

1991 ◽  
Vol 18 (4) ◽  
pp. 690-710
Author(s):  
Hany Ahmed El-Ghazaly ◽  
Heyad Saud Al-Zamel
Keyword(s):  
Concrete Beam ◽  
Experimental Testing ◽  
Precast Concrete ◽  
Steel Frame ◽  
Reinforcing Bars ◽  
Shear Tests ◽  
Moment Connections ◽  
Modes Of Failure ◽  
Moment Resisting ◽  
Flexural Tests

A new detail is introduced for precast concrete beam-to-column moment connections. The detail consists of a connecting steel frame used to mechanically connect the threaded end protruding reinforcing bars from beam and column. The connection detail is made convenient to assemble where the erection method resembles that of steel construction. No idle crane time is necessary, since the connecting steel frame is designed to carry the beam's own weight. When the connection construction is completed, the joint functions as a moment resisting hard connection. The experimental testing program involved testing of twelve full-scale specimens in addition to a pilot test. Of the twelve tests seven are flexural tests, three are shear tests, and two are monolithic flexural tests for comparison. Modes of failure in the flexural tests were mainly due to rupture of tension reinforcement; however, premature slippage of the rebars may occur under certain conditions, but could be conveniently prevented. In the shear tests, diagonal tension crack failure predominated. If the connection parameters are properly selected, the connection will be capable of developing the beam's full plastic moment and undergo sufficient rotation before collapse. Key words: precast concrete, moment connections, connecting steel frame, stiffness, strength, ductility.

The Evolving Basis for the Design of Light Gauge Steel Systems

2020 ◽  
Vol 20 (13) ◽  
pp. 2041008
Author(s):  
Pinelopi Kyvelou ◽  
David A. Nethercot ◽  
Nicolas Hadjipantelis ◽  
Constantinos Kyprianou ◽  
Leroy Gardner
Keyword(s):  
Numerical Models ◽  
Numerical Approach ◽  
Superior Performance ◽  
Exact Nature ◽  
Beneficial Effects ◽  
Plate Elements ◽  
Different Types ◽  
Test Behavior ◽  
General Basis ◽  
The Many

The importance of allowing for the many different types of structural interaction that have an effect on the performance of light gauge members when used in practical situations is emphasized. A distinction is drawn between internal interactions involving the various plate elements of the steel profiles and external interactions involving the other components in the system. Although full-scale testing of representative systems can capture this behavior, the costs involved make this an impractical general basis for design; codified methods generally consider only isolated plates within members and isolated members within systems, thereby neglecting the potentially beneficial effects of both forms of interaction. Properly used, modern methods of numerical analysis offer the potential to systematically allow for both forms of interaction — provided the numerical models used have been adequately validated against suitable tests. The use of such an approach is explained and illustrated for three commonly used structural systems: roof purlins, floor beams, and columns in stud walls. In each case, it is shown that, provided sufficient care is taken, the numerical approach can yield accurate predictions of the observed test behavior. The subsequently generated large portfolio of numerical results can then provide clear insights into the exact nature of the various interactions and, thus, form the basis for more realistic design approaches that are both more accurate in their predictions and which lead to more economic designs. Building on this, modifying existing arrangements so as to yield superior performance through specific modifications is now possible. Two such examples, one in which improved interconnection between the components in a system is investigated and a second in which prestressing is shown to provide substantial enhancement for relatively small and simple changes, are presented.

Innovative connections for precast concrete moment resisting frames

2015 ◽  
Vol 48 (3) ◽  
pp. 204-221
Author(s):  
Farhad Behnamfar ◽  
Hadi Rafizadeh ◽  
Mortza Omidi
Keyword(s):  
Compressive Strength ◽  
Numerical Study ◽  
Precast Concrete ◽  
Research Work ◽  
Displacement Curve ◽  
Moment Connections ◽  
Moment Resisting ◽  
Compressive Strength Of Concrete ◽  
Design And Practice ◽  
Strength And Ductility

This research work presents new details for moment connections in precast concrete structures satisfying both design and practice criteria. In this paper the results of the numerical study on the connections are presented. For the analysis, the ANSYS software is selected because of its diversity in nonlinear analysis. By calculating the monotonic load-displacement curve of each connection, the connections are evaluated for their stiffness, strength, and ductility. The compressive strength of the connection concrete is taken to be 30, 35 and 40 MPa, for each round of analysis. The results of the analysis show that the proposed connections are stiff enough to be moment resisting and to be emulating an equivalent monolithic, or basic connection. It is illustrated that the connections are stronger but somewhat less ductile than the basic connection regardless of the concrete strengths examined. Moreover, it is shown that in each precast connection while increasing the compressive strength of concrete does not affect the connection stiffness considerably, it increases the ultimate load and ductility of the connection. As a main result of this study, the suggested connection details are categorized based on their stiffness, strength, and ductility. The suggested connections can be used in moment resisting precast concrete buildings based on the desired strength and ductility.

Analytical Models for Determining Rotational Capacity of Clip-Angle Connections under Seismic Loading

2014 ◽  
Vol 1025-1026 ◽  
pp. 979-986
Author(s):  
Jong Wan Hu ◽  
Hong Min Son
Keyword(s):  
Mathematical Models ◽  
Curve Fitting ◽  
Steel Frames ◽  
Seismic Loading ◽  
Full Scale ◽  
Analytical Models ◽  
Cyclic Loads ◽  
Structural System ◽  
Ductile Behavior ◽  
Partially Restrained

This paper explores rotational capacities and demands in thick top-and-seat (cleated) angle partially restrained connections subjected to monotonic and cyclic loads. The results of test on full-scale angle connections are described first, and are then compared to published curve-fitting models for these types of connections. The data indicates that the curve-fitting constants of some existing mathematical models cannot be extrapolated to thick angles. The results indicate that these connections are capable of providing very ductile behavior and constitute an ideal back-up structural system in steel frames.

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