Editor’s Note
Publication: Journal of Structural Engineering
Volume 136, Issue 2
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John W. van de Lindt
I would like to begin by introducing our newest member of the editorial board, John W. van de Lindt who will assist us in the review of papers in the area of wood structures. Dr. van de Lindt is an associate professor of structural engineering at Colorado State University where he teaches both undergraduate and graduate courses. He joined the department in 2004 after having been on the faculty at Michigan Tech from 2000 to 2004. His research program has two major thrusts, both related to improving the built environment by making structures and structural systems perform to the level expected by their occupants, government, and the public. He seeks to accomplish this through the development and test bed applications of performance-based engineering of building systems and bridges for earthquakes, hurricanes, and floods. Accomplishing this has necessitated coupling nonlinear dynamics, including stochastic approaches in both time and space, with structural reliability during extreme loading events such as earthquakes, hurricanes, and tsunamis. He has worked for the last decade at moving performance-based design for wood structures forward via committee and research activities and published numerous papers in those areas. Dr. van de Lindt currently serves as the coordinator for the Structural Engineering and Structural Mechanics (SESM) program at Colorado State University and formerly was the chair of the Technical Administrative Committee on Wood, which oversees the four national ASCE/SEI wood committees. He received his B.S. from California State University at Sacramento in 1993 and his M.S. and Ph.D. from Texas A&M University in 1995 and 1999, respectively. In addition to ASCE he is a member of EERI, CUREE, and NEES.
This Month in JSE
Structural Control
Weber et al. numerically investigate “Optimal Tuning of Amplitude Proportional Coulomb Friction Damper for Maximum Cable Damping” where the optimality criterion is maximum additional damping in the first vibration mode. It is shown that the friction force level has to be adjusted in proportion to cable amplitude at damper position, which is realized by amplitude feedback in real time.
“Modular High-Force Seismic Magneto-Rheological Fluid Damper” for seismic mitigation applications is introduced by Gordaninejad et al. The performance of the proposed large-scale magneto-rheological fluid (MRF) valve and the combined semiactive bypass MRF damper are examined through quasi-static and dynamic tests.
Structural Identification
A method for “Parametric Estimation for RC Flexural Members Based on Distributed Long-Gauge Fiber Optic Sensors” is examined by Li and Wu. An integrated strategy for long-term structural health monitoring is proposed to identify structural parameters such as curvature and average stiffness of RC flexural members.
Shock and Vibratory Effects
In “Air-Blast Effects on Structural Shapes of Finite Width,” Ballantyne et al. investigate the effect of finite flange width on blast loadings on structural components. The diffraction of a blast wave around the leading edges of a column cross section and the propagation of rarefaction waves from the leading edges to the column centerline results in a process called “clearing,” which is expected to lead to a more rapid reduction in reflected pressure than that of an infinite surface. Numerical simulations carried out by the writers indicate that peak reflected pressures are not changed by the “finiteness” of the section, although the reflected impulse can be substantially reduced by clearing.
Wind Effects
In “Tall Building Response Parameters: Sensitivity Study Based on Orthogonal Factorial Experiment Design Technique,” Filliben and Simiu demonstrate that wind load factors for tall buildings depend significantly upon uncertainties with respect to natural frequencies of vibration and damping ratios. Because this dependence is disregarded in the ASCE 7-05 Standard, wind load factors specified therein can lead to safety levels that are significantly lower for flexible buildings than for rigid buildings.
Analysis and Computation
“Parallel Axial-Flexural Hinge Model for Nonlinear Dynamic Progressive Collapse Analysis of Welded Steel Moment Frames” is proposed by Lee et al. A multilinear parallel point hinge model that captures the moment-axial tension interaction is used to develop a computationally efficient macro model for practical progressive collapse analysis. The response of ductile steel moment frames under a column-missing scenario is investigated using parametric nonlinear finite element analysis.
Metal and Composite Structures
In “Behavior of Hollow Tubular-Flange Girder Systems for Curved Bridges,” Donga and Sause present findings from an investigative study on an innovative curved highway bridge girder system. It is shown through numerical simulations that the increased torsional stiffness provided by the tubular flanges dramatically improves the structural behavior of the curved girders, resulting in substantially reduced deflection, cross-section rotation, and stress compared to conventional curved I-shaped steel plate girders.
Results of several composite beam tests incorporating trapezoidal steel decking are presented by Ernst et al. in “Correlation of Beam Tests with Pushout Tests in Steel-Concrete Composite Beams.” The experiments were especially designed to gain insight into the ductility of the shear connection when subject to the so-called “brittle” failure modes of the concrete slab observed in small-scale push-out tests, and to examine the suitability of novel reinforcing measures such as waveform reinforcement components or stud performance-enhancing devices.
The permissible “Moment Redistribution in Continuous Steel-Concrete Composite Beams with Compact Cross Section,” which satisfies the requirements of ultimate (collapse) and serviceability (crack width in slab) limit states. is evaluated by Gattesco et al. An extensive numerical parametric study was conducted to establish the moment redistribution domain that satisfies the rotation compatibility in critical sections due to rupture of the reinforcement or local buckling of the steel profile and the control of cracking.
Concrete Structures
In “Automated Finite-Element-Based Validation of Structures Designed by the Strut-and-Tie Method,” Park et al. present an integrated strut-and-tie method (STM) design and computational framework that overcomes some existing barriers to efficient design by the STM, particularly for nonductile and complex structures, as revealed by experiments in which some STM designed structures have exhibited poor performance at service load levels and/or not been able to support their calculated nominal design strength.
Wood Structures
Song and Lam present a study on the “Stability Capacity and Lateral Bracing Requirements of Wood Beam-Columns” subjected to biaxial eccentric compression loads. A numerical simulation model is developed to predict maximum compression load, midspan lateral deflection, and lateral bracing forces and validated against experimental data. A parametric study is carried out to investigate the adequacy of current methods to estimate bracing forces and requirements for different conditions.
Special Design Issues
A simplified methodology is developed by Frangi et al. for “Fire Design of Timber-Concrete Composite Slabs with Screwed Connections.” The effects of temperature on the mechanical properties of timber, concrete, and the connection are taken into account by the development of modification factors based on the results of an extensive experimental study on the fire behavior of the screwed connections. The behavior and modeling of the screwed connection subjected to fire loading is discussed followed by comparisons of the proposed methodology to results obtained from a full-scale fire test.
Discussion and Closure
The issue concludes with a discussion by Abbas Moustafa on the paper “Analytical Model of Ground Motion Pulses for the Design and Assessment of Seismic Protective Systems” by He and Agrawal, which appeared in the July 2008 issue of the Journal. The comments of the discusser are addressed in a closure by the original writers.
Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 136 • Issue 2 • February 2010
Pages: 121 - 122
Copyright
© 2010 ASCE.
History
Received: Nov 5, 2009
Accepted: Nov 6, 2009
Published online: Jan 15, 2010
Published in print: Feb 2010
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