scholarly journals MACRO-ELEMENT MODEL OF A STEEL MOMENT FRAME SUBJECTED TO FIRE-INDUCED COLUMN LOSS

2016 ◽  
Author(s):  
Ha Nguyen ◽  
Ann E. Jeffers ◽  
Venkatesh Kodur
Keyword(s):  
Progressive Collapse ◽  
Experimental Tests ◽  
Element Model ◽  
Fe Model ◽  
Structural System ◽  
Moment Frame ◽  
Moment Connections ◽  
Steel Moment Frame ◽  
Collapse Mechanisms ◽  
Macro Element

A progressive collapse mitigation strategy is to ensure load redistribution when a column fails due to fire. The study seeks to understand whether welded unreinforced flange-bolted web (WUF-B) moment connections can effectively redistribute loads in a structural system subjected to fire when a critical column is lost. A component (or macro-element) model was derived to simulate the WUF-B connection and validated against experimental tests and high-resolution finite element (FE) models of subassemblies at room temperature and at elevated temperature. The component model was then utilized in a 2D macro FE model of a ten-story steel-framed building subjected to the loss of a column during long fire exposure. This paper presents the collapse mechanisms and quantifies structural performance based on acceptance criteria. A parametric study on location of column loss and fire occurrence is also included.

Computational simulation of steel moment frame to resist progressive collapse in fire

2016 ◽  
Vol 7 (4) ◽  
pp. 286-305 ◽  
Author(s):  
Ha Nguyen ◽  
Ann E. Jeffers ◽  
Venkatesh Kodur
Keyword(s):  
Experimental Data ◽  
Large Scale ◽  
Progressive Collapse ◽  
Computational Simulation ◽  
Three Dimensional ◽  
Fe Model ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Fixed Temperature ◽  
Content Type

Purpose This paper aims to address a need for improving the structural resilience to multi-hazard threats including fire and progressive collapse caused by the loss of a column. Design/methodology/approach The focus is on a steel moment frame that uses welded-unreinforced flange-bolted web connections between the beams and columns. A three-dimensional finite element (FE) model was created in ABAQUS with temperature-dependent properties for steel based on the Eurocode. The model was validated against experimental data at ambient and elevated temperature. Findings The failure mechanisms in the FE model were consistent with experimental observations. Two scenarios were considered: fixed load with increasing temperature (i.e. simulating column failure prior to fire) and fixed temperature with increasing load (i.e. simulating column failure during fire). Originality/value A macro element (or component-based) model was also introduced and validated against the FE model and the experimental data, offering the possibility of analyzing large-scale structural systems with reasonable accuracy and improved computational efficiency.

Relative Performance of Kobe and Northridge WSMF Buildings

2006 ◽  
Vol 22 (4) ◽  
pp. 1081-1101 ◽  
Author(s):  
Bruce F. Maison ◽  
Kazuhiko Kasai ◽  
Yoji Ooki
Keyword(s):  
Los Angeles ◽  
The United States ◽  
Office Building ◽  
Superior Performance ◽  
Moment Frame ◽  
Moment Connections ◽  
Steel Moment Frame ◽  
Welded Steel ◽  
The Difference ◽  
Seismic Behaviors

Seismic behaviors of a five-story welded steel moment-frame (WSMF) office building in Kobe, Japan, and a six-story WSMF office building in Northridge, California, are compared. Both experienced earthquake damage (1995 Kobe and 1994 Northridge earthquakes, respectively). Computer models of the buildings are formulated, having the ability to simulate damage in terms of fractured moment connections. Analyses are conducted to assess building response during the earthquakes. The calibrated models are then analyzed using a suite of earthquake records to compare building performance under consistent demands. The Kobe building is found to be more rugged than the Northridge building. Analysis suggests it would experience much less damage than the Northridge building from shaking equivalent to 2,500-year earthquake for a generic Los Angeles site. Superior performance of the Kobe building is attributed to its relatively greater stiffness and strength. The results provide insight into the difference in seismic fragility expected for this class of mid-rise WSMF buildings in Japan and the United States.

Design and Fatigue Life Analysis of a Motorcycle Frame

2014 ◽  
Author(s):  
Massimiliano Gobbi ◽  
Giorgio Previati ◽  
Giampiero Mastinu
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Finite Element Model ◽  
Experimental Tests ◽  
Element Model ◽  
Fe Model ◽  
Static Test ◽  
Weld Toe ◽  
Fatigue Life Analysis ◽  
Motorcycle Frame

An off-road motorcycle frame has been analyzed and modified to optimize its fatigue life. The fatigue life of the frame is very important to define the service life of the motorcycle. The strain levels on key parts of the frame were collected during experimental tests. It has been possible to locate the areas where the maximum stress level is reached. A finite element (FE) model of the frame has been developed and used for estimating its fatigue life. Static test bench results have been used to validate the FE model. The accuracy of the finite element model is good, the errors are always below 5% with respect to measured data. The mission profile of the motorcycle is dominated by off-road use, with stress levels close to yield point, so a strain-life approach has been applied for estimating the fatigue life of the frame. Particular attention has been paid to the analysis of the welded connections. A shell and a 3D FE model have been combined to simulate the stress histories at the welds. Two reference maneuvers have been considered as loading conditions. The computed stresses have been used to assess the life of the frame according to the notch stress approach (Radaj & Seeger). The method correlates the stress range in a idealized notch, characterized by a fictitious radius in the weld toe or root, to the fatigue life by using a single S-N curve. New technical frame layouts have been proposed and verified by means of the developed finite element model. The considered approach allows to speed up the design process and to reduce the testing phase.

Vibration-Based Seismic Damage Identification in Buildings

2005 ◽  
Vol 293-294 ◽  
pp. 727-734
Author(s):  
José L. Zapico ◽  
María P. González
Keyword(s):  
Natural Frequencies ◽  
Damage Identification ◽  
Element Model ◽  
Seismic Damage ◽  
Frame Structure ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Data Errors ◽  
Simplified Finite Element Model ◽  
Storey Building

This article deals with a method for seismic damage identification in buildings with steel moment-frame structure. The damage identification is based on artificial neural networks and natural frequencies. A simplified finite element model is used to obtain the data needed for training the nets. The method is simulated on a four-storey building under conditions as close as possible to reality. The robustness of the method and its sensitivity to the variations of the mass with time and the influence of the data errors is addressed. The statistical analysis of the results is successful, but it reveals that the predictions are quite sensitive to the data errors.

Insight Into the Design of Blast-Mitigating Floor Mats Using Design of Experiments

2019 ◽  
Author(s):  
Hisham Kamel
Keyword(s):  
Design Of Experiments ◽  
Computational Study ◽  
Close Contact ◽  
Dynamic Performance ◽  
Experimental Tests ◽  
Element Model ◽  
Influential Factor ◽  
Fe Model ◽  
Energy Absorbing ◽  
Insight Into

Abstract Recently, Improvised explosive devices (IEDs) have evolved into a major and significant threat inflicting substantial human casualties and property damage. The majority of injuries are to the lower extremities since they are in close contact to vehicle floor. Floor mats have been developed to mitigate the effects of IEDs blasts. This paper reports a computational study on the energy absorbing behavior of a novel commercial floor mat — Skydex — for foot protection. The design of experiments (DOE) approach was applied to investigate the effect of shape variations on the dynamic performance of a finite element model of Skydex. The FE model was verified using experimental tests on samples produced using 3D printing technique. The DOE approach revealed significant insight into the design of Skydex. It confirmed that shape variables have strong effect on the amount of energy absorbed and the transmitted load. DOE specifically identified the radius of the mid-section of Skydex as the most influential factor in controlling the mode of deformation under compression. In addition, it uncovered the interaction effect between the radius of curvatures of the two hemispheres and upper and lower radii. Finally, DOE revealed the bi-trade-off relations between energy absorbed, transmitted load and mass. These were shown in meaningful and helpful plots which will help the development of Skydex design.

Manhattan West: Converting Site Challenges into Design Opportunities

2019 ◽  
Author(s):  
Preetam Biswas ◽  
Georgi I. Petrov ◽  
Yunlu Shen ◽  
Samuel Wilson ◽  
Charles Besjak
Keyword(s):  
New York ◽  
Structural System ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Concrete Core ◽  
The Core ◽  
Steel Core ◽  
Train Tracks ◽  
Penn Station ◽  
Structural Solutions

<p>As cities worldwide are increasing in density, building departments and municipalities are allowing construction using the air‐rights above transportation infrastructure to maximize use of valuable real estate. One Manhattan West (1MW) and Two Manhattan West (2MW) are supertall office towers recently designed and engineered by Skidmore, Owings &amp; Merrill (SOM) that rise above the underground train approach to New York City’s Penn Station. Although the towers are neighbors and have a similar program, they are undercut by the train tracks in different ways. The disparate below ground conditions result in two distinct structural solutions.</p><p>The structural system of 1MW is a concrete core and a perimeter steel moment frame. The site conditions prevent the perimeter of the 304‐meter‐tall tower from reaching the foundation. This challenge is addressed by transferring the perimeter to the core above the ground, thus making 1MW one of the slenderest structures in New York City. The structural system of 2MW consists of a central braced steel core with outrigger and belt trusses and a perimeter steel moment frame. Here the perimeter reaches the foundation with a few lateral transfers however only half of the core reaches terra firma. This paper presents a side‐by‐side comparison of the structural solutions for the two towers.</p>

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