Editor’s Note

The leadoff paper by Chi et al. proposes a measure for “Prediction of Ductile Fracture in Steel Connections Using SMCS Criterion.” The accuracy of the criterion is demonstrated for specimens with a range of triaxial constraint conditions including both sharp-crack fracture specimens and blunt-notch specimens. David Duerr discusses theoretical and experimental studies over the past $65\text{years}$ in “Pinned Connection Strength and Behavior.” A single consistent set of equations for both elastic stress and ultimate strength are developed. Results from two full-scale tests are reported by Driver et al. in “Shear Behavior of Corrugated Web Bridge Girders.” The authors contend that previously proposed equations based on plate buckling theories can overestimate the shear strength of corrugated web girders due to the influence of initial geometric imperfections. “Design of Slender Angle Section Beam-Columns by the Direct Strength Method” is presented by Rasmussen, which involves the determination of the local buckling strength under combined bending and compression. The behavior of “Complex Edge Stiffeners for Thin-Walled Members” is investigated by Schafer et al. Nonlinear finite-element analysis is used to examine the postbuckling and ultimate strength regime of complex stiffeners, which are shown to provide improved performance over simple stiffeners. Simplified equations and practical assessment charts are developed by Seracino et al. in “Partial Interaction Shear Flow Forces in Continuous Composite Steel-Concrete Beams.” The approach is compatible with the tiered assessment approach previously developed for simply supported beams and is shown to be applicable to continuous beams with any number of spans, varying span lengths, and varying connector distribution or cross-section. The final paper in this section deals with the use of adhesively bonded fiber-reinforced polymers (FRP) in metal structures. Authored by Wendel Sebastian, “Performance Implications of Imperfectly Plastic Material in Metallic Structures with Nonmetallic Reinforcement” suggests that robust prediction of performance requires accurate constitute models for the metal.

A new method that overcomes the problems with nonobjective response caused by strain-softening behavior is proposed by Scott and Fenves in “Plastic Hinge Integration Methods for Force-Based Beam-Column Elements.” Derived from the Gauss-Radau quadrature rule, deformations are integrated over the specified plastic hinge length at the ends of the element and are shown to reduce to the exact solution for linear problems. The presented examples show that the proposed method is a straightforward means of incorporating a physically meaningful plastic hinge length in simulating the strain-softening response of frame structures. Wang et al. derive an analytical expression for the thickness variation of submerged domes in “Membrane Analysis and Minimum Weight Design of Submerged Spherical Domes.” By adopting a uniform strength design governed by the Tresca yield criterion, it is demonstrated that there exists an optimal subtended angle wherein a minimum dome weight is achieved.

Terje Haukaas presents a novel event-based strategy for “Efficient Computation of Response Sensitivities for Inelastic Structures,” whereby sensitivities of the final response are obtained more efficiently than by the ordinary direct differentiation method. Numerical examples validate the efficiency of the development. The structural reliabilities of a series of steel frames designed by both LRFD and advanced analysis methods are compared by Buonopane and Schafer in “Reliability of Steel Frames Designed with Advanced Analysis.” Findings from the study indicate that LRFD methods successfully enforce the target reliability on first plastic hinging while advanced analysis methods results in acceptable reliabilities against plastic collapse but relatively large probabilities of plastic hinging at service load levels.

A multicriteria optimization method for performance-based seismic design is proposed by Xu et al. in “Seismic Design Optimization of Steel Building Frameworks.” The overall objective is to achieve minimum structural weight and uniform plastic ductility demand while satisfying displacement and strength constraints corresponding to desired performance levels. Pushover analysis is employed to establish plastic behavior under equivalent-static seismic loading. Damage is defined in terms of ductility demand, which in turn is associated with the coefficient of variation of interstory drift. Numerical examples are presented to verify the approach.

The dynamic response of porcelain bushings mounted on transformer tanks is investigated by Filiatrault and Matt in “Seismic Response of High-Voltage Electrical Transformer-Bushing Systems.” It is shown that large amplification can occur when the fundamental frequency of the porcelain bushing is tuned with the fundamental frequency of the transformer tank. Burton et al. characterize the biodynamic human body vibration response occurring during low-frequency, constant amplitude sinusoidal accelerations in “Frequency Dependence of Human Response to Wind-Induced Building Motion.” The human body vibration is found to be frequency dependent in the range of $0.15\text{to}1.00\mathrm{Hz}$ , with implications for visual perception of motion through parallax shift. The study calls for more refined occupant comfort criteria for tall building motion.

Ritdumrongkul and Fujino demonstrate that a piezoeceramic (PZT) patch can be used simultaneously as an actuator and a damage sensor in “Identification of the Location and Level of Damage in Multiple-Bolted-Joint Structures by PZT Actuator Sensors.” The measurement of the electrical impedance of the PZT patch provides a basis for identifying changes in the structural properties. Validation of the proposed idea is achieved through laboratory experiments and numerical simulations.

A strain energy method is used by Wadud and Ahmad to develop “Design Charts for Helicoidal Stair Slabs with Landing at Midspan.” Different geometric parameters have been considered and nondimensional parameters are used to derive design charts for use by practicing engineers. A parametric study by the authors reveals that the presence of a landing significantly effects the maximum vertical moment and torsion, and the landing span influences the distribution of vertical moment, torsion, and vertical shear along the span.

This issue also includes two discussions on previously published papers. The first discussion by David Brosnan on a paper by Chiewanichakorn et al. that appeared in the December 2004 issue of the journal takes issue with conclusions reached by the authors on the effective width of composite bridge girder sections. The next discussion concerns the paper “Evaluation of Fire Endurance of Concrete Slabs Reinforced with Fiber-Reinforced Polymer Bars” that appeared in the January 2005 issue. William Gamble raises questions on the bond strength of FRP reinforcement in addition to pointing to an error and possible omissions in the paper. The authors of the original papers offer their opinions and provide clarification to the issues raised by the discussers.

Mu., B., et al. (2006). “FE analysis of complex bridge system with FRP composite deck.” J. Compos. Constr., 10(1).

Chaallal, O., et al. (2006). “Circular columns confined with FRP: Experimental versus predictions of models and guidelines.” J. Compos. Constr., 10(1).

Tastani, S. P., et al. (2006). “Limitations of FRP-jacketing in confining old-type RC members in axial compression.” J. Compos. Constr., 10(1).

Barr, P. J., et al. (2006). “Long-term structural health monitoring of the San Ysidro Bridge.” J. Perform. Constr. Facil., 20(1).

Setareh, M., et al. (2006). “Pendulum tuned mass dampers for floor vibration control.” J. Perform. Constr. Facil., 20(1).

Pearson, C., and Delatte, N. (2006). “The collapse of the Quebec Bridge, 1907.” J. Perform. Constr. Facil., 20(1).

Yoshihara, H., and Kawasaki, T. (2006). “Failure behavior of spruce wood under bending-shear combined stress field.” J. Mater. Civ. Eng., 18(1).