Editor’s Note

The issue begins with a two-part paper by Carden et al. that examines the seismic response of girder bridges with two different types of cross braces. The first paper investigates the “Seismic Performance of Steel Girder Bridges with Ductile Cross Frames Using Single Angle X-Braces.” Large-scale, reversed static load, and shake-table experiments demonstrated that the cross frames are able to accommodate large drifts and act as effective structural fuses. In the second paper, the writers compare the performance of buckling-restrained braces (BRBs) against the response of X-braces presented in the previous paper. Shake-table testing of a large-scale bridge model with BRBs using both pin-ended and fixed-end connections is carried out. The pin-ended connections are reported to be more effective and the maximum cross frame displacements are shown to be consistently smaller for the same level of shear than those in X-braces for the same level of shear.

Zhang and Ricles describe results from an “Experimental Evaluation of Reduced Beam Section Connections to Deep Columns.” Specimens having a composite floor slab or no floor slab and a supplemental lateral brace at the RBS were able to satisfy AISC seismic-connection qualification criteria. A follow-on paper presents a parametric study on the “Seismic Behavior of Reduced Beam Section Moment Connections to Deep Columns.” Calibrated finite element models of the connections in special moment frames were analyzed under inelastic monotonic and cyclic loading. An RBS connection to a deep column is shown to have less potential for ductile fracture in the connection region than a welded unreinforced flange connection, whereas the potential for fracture increases when the column section properties are reduced.

A two-part paper investigating the “Static Strength of Cracked Square Hollow Section T Joints under Axial Loads” is presented by Lie et al. The first paper reports on a series of full-scale tests in which crack propagation and crack mouth opening displacements were monitored during the testing. Results indicate that provisions in the British Standards provide an adequate procedure for assessing cracked square-to-square hollow section T joints. The second paper proposes a numerical model for automatic mesh generation of the SHS T joint region. Following validation of the model with experimental data, a parametric study is carried out to estimate plastic collapse loads for different geometric configurations. The yield line theory provides reasonable predictions when the brace-to-chord width ratio is less than 0.8.

The influence of a range of variables on the effective stiffness $EI$ is examined by Tikka and Mirza in “Nonlinear Equation for Flexural Stiffness of Slender Composite Columns in Major Axis Bending.” A new equation for the effective stiffness of slender composite columns is proposed and demonstrated to be more reliable than the current expression in ACI-318 provisions. “Experimental In-Plane Shear Strength Investigation of Reinforced Concrete Masonry Walls” is described by Voon and Ingham. Test results indicate that masonry shear strength increases with the magnitude of the applied compressive stress and the amount of shear reinforcement but that it decreases with increasing wall aspect ratio. An improvement in performance is achieved by uniformly distributing the shear reinforcement up the height of the walls.

Peter Ellegaard discusses the analysis of timber trusses in “Finite-Element Modeling of Timber Joints with Punched Metal Plate Fasteners.” The model incorporates semirigid and nonlinear behavior of the joints and contact between timber beams. The results from experimental tests with two types of nail plate joints are compared with theoretical predictions. The model reasonably estimates joint behavior only at lower load levels. The results of linear static analysis for “Time-Dependent Behavior of Posttensioned Wood Howe Bridges” are reported by Gasparini et al. A linear viscoelastic analysis is formulated. It uses a standard linear solid constitutive model and predicts the time-dependent behavior of the Pine Bluff Bridge in Indiana. First-order reliability analyses are carried out by Bulleit to assess the “Reliability of Steel Doweled Wood Connections Designed to ASCE 16-95.” The study concludes that designs to ASCE 16-95 do not consistently exhibit reliability across the range of possible designs. Consistency is increased by utilizing the full set of yield equations rather than the simplified set given in ASCE.

Atahan uses commercial software to analyze and improve the crash test behavior of New York Department of Transportation portable concrete barriers in “Finite Element Crash Test Simulation of New York Portable Concrete Barrier with I-Shaped Connector.” A finite element representation of a full-scale crash test is developed and validated with observed response. An improved concrete barrier is developed by using adequate welding details and is analytically shown to be successful in containing and redirecting the impacting vehicle in a stable manner.

A nonlinear model that predicts load-deflection response and axial-flexure interaction curves is presented by Mandal and Fam in “Modeling of Prestressed Concrete-Filled Circular Composite Tubes Subjected to Bending and Axial Loads.” The model is verified by using experimental results and is then used in a parametric study to evaluate the effects of prestress level, amount and material type of prestressed reinforcement, and thickness and laminate structure of the tube.

The safety of pile foundations is evaluated by Tonon in “Interaction Diagram and Load Effects for Vertical Pile Groups with Application to the AASHTO-LRFD.” Convex analysis and computational geometry are used to evaluate load effects, and expressions are derived for assessing when the methods of computational geometry are efficient compared with considering all load combinations. A numerical example is presented to demonstrate the application of the procedure.

“Observations on the Reliability of Alternative Multiple-Mode Pushover Analysis Methods” by Tjhin et al. compares estimates of response quantities determined with the alternative pushover methods for five buildings subjected to suites of scaled ground motions. The writers point to numerous discrepancies between pushover procedures and nonlinear time-history estimates and conclude that the robustness of nonlinear static procedures is questionable. A “Hysteretic Model of Stiffened Shear Panel Dampers” is proposed by Chen et al. as a passive energy dissipating device (PEDD) for buildings and bridges. A series of steel shear panels with one-, two-, or three-way stiffeners was analyzed by using commercial finite element software in which the web slenderness was the primary system variable. A simplified bilinear model for the PEDD is recommended. The final technical note, by Thomas and Noldred proposes an “Empirical Punching Shear Failure Theory for Oriented Strand Board: Preliminary Study.” A hypothetical shear perimeter that is a distance equal to the thickness away from the boundary of the loaded area is shown to enable reasonable prediction of the shear capacity of oriented stand board.

Also included in this issue is a discussion by Sissakis and Sheikh on the paper “Punching Shear Strengthening of Reinforced Concrete Flat Plates Using Carbon Fiber Reinforced Polymers.” The original article was published in September 2003. The discussers offer additional information on FRP strengthening of two-way slabs that was completed at the University of Toronto. The original writers point out salient differences between the research conducted at Texas and the data generated at Toronto although the overall efficiency of both retrofitting approaches was comparable.

Berglund, E. M., and Schultz, A. E. (2006). “Girder differential deflection and distortion-induced fatigue in skewed steel bridges.” J. Bridge Eng., 11(2).

Chou, C. C., Uang, C.-M., and Seible, F. (2006). “Experimental evaluation of compressive behavior of orthotropic steel plates for the new San Francisco–Oakland Bay Bridge.” J. Bridge Eng., 11(2).

Christenson, R. E., Spenser, B. F., Jr., and Johnson, E. A. (2006). “Experimental verification of smart cable damping.” J. Eng. Mech., 132(3).

Dai, H., and Gasparini, D. A. (2006). “Dynamic behavior of nonlinear cable system.” J. Eng. Mech., 132(3).

Ma, G.-W., Liu, Y., and Li, Q. (2006). “Numerical simulations of dynamic instability of elastic-plastic beams.” J. Eng. Mech., 132(3).

Nevling, D., Linzell, D. G., and Laman, J. A. (2006). “Examination of level of analysis accuracy for curved I-girder bridges through comparisons to field data.” J. Bridge Eng., 11(2).

Xiao, Y., Wu, H., Yaprak, K., Martin, G. R., and Mander, J. B. (2006). “Experimental studies on seismic behavior of steel pile-to-pile-cap connections.” J. Bridge Eng., 11(2).