Editor’s Note

The opening paper in this issue by Fafitis proposes a new method for “Nonlinear Truss Analysis by One Matrix Inversion.” Nonlinearities arising from various sources are handled by iterations involving only multiplications of the banded matrix with a transformed force vector. Load increments may be nonproportional and the method can be used in pushover and quasistatic cyclic analysis. Asta and Zona present “Finite-Element Model for Externally Prestressed Composite Beams with Deformable Connection.” The formulation describes the behavior of steel-concrete composite beams with deformable shear connections and cables, which can have general paths and slip without friction at the deviators. Simulations of a numerical implementation of the model is shown to compare well with experimental results. The modeling of the inelastic behavior of beams with composite slabs in steel moment frames is the subject of the next paper, “Composite Beam Element for Nonlinear Seismic Analysis of Steel Frames,” by Kim and Engelhardt. The single-component series hinge-type model is validated with findings from experimental testing.

The next group of papers deals with seismic effects on structures. Sweedan and El Damatty utilize a coupled finite-boundary element formulation to develop “Equivalent Models of Pure Conical Tanks under Vertical Ground Excitation.” Normal forces on the wall as well as on the base of the conical vessel are computed, and variations of these parameters with geometric properties of the vessel are organized in chart form. The capabilities of semiactive control systems are investigated by Yoshida and Dyke in “Response Control of Full-Scale Irregular Buildings Using MR Dampers.” Genetic algorithms are used to effectively place control devices on two full-scale model buildings, and semiactive control systems are compared to ideal active and passive control systems through numerical simulations. “Comparative Study on Vibration Control of a Scaled Bridge Using Fail-Safe MR Fluid Dampers” is presented by Liu et al. It is experimentally demonstrated that the semiactive control system can reduce relative deck displacement without affecting the absolute deck acceleration.

Equations commonly used to estimate short-term deflections are evaluated by Bischoff in “Reevaluation of Deflection Prediction for Concrete Beams Reinforced with Steel and FRP Bars.” An alternative expression that incorporates a tension-stiffening model is developed and is shown to work for both steel and FRP bars. Qian et al. investigate the plastic yield behavior of material with microvoids in “Simulation of Ductile Fracture of CHS Joints using the Gurson Model.” The effect of void growth and nucleation are observed to be more prominent in the axial tensile mode than the shear mode. The K-joint is found to be less sensitive to the variation of nucleation parameters as compared to X- and T-joints.

An approach for “Modeling Wood Walls Subjected to Combined Transverse and Axial Loads” is developed by Bulleit et al. Monte Carlo simulation is used in sensitivity studies of the transverse ramp-load behavior of walls under various levels of axial load, and the model is shown to capture the range of possible behavior of stud walls. Doudak et al. report on findings from “Monitoring Structural Response of a Wooden Light-Frame Industrial Shed Building to Environmental Loads.” Measured response confirms theoretical expectations that composite action and load sharing are important mechanisms for light-frame buildings. An experimental investigation on the translational behavior of timber joints is described by Porteous and Kermani in “Fully Overlapping Nailed Joints with Steel Gussets in Timber Structures.” The results are used to develop an empirical load-displacement model enveloping response states up to failure of the joint.

Wind tunnel tests to determine the shape and vibration coefficient are presented by Yue et al. in “Wind Load on Integral-Lift Scaffolds for Tall Building Construction.” Random vibration theory is utilized to develop formulae for predicting wind vibration coefficients during erection and dismantling of integral-lift scaffolds. Gust factors for over-land and over-water cases are examined by Vickery and Skerlj in “Hurricane Gust Factors Revisited.” Findings from the study indicate that in most cases hurricane gust factors can be described using models developed for standard neutral boundary layer flow conditions. Liu and Frangopol propose a “Multiobjective Maintenance Planning Optimization for Deteriorating Bridges Considering Condition, Safety, and Life-Cycle Cost.” A genetic algorithm is utilized as the search engine to identify alternative maintenance scenarios that exhibits an optimized trade-off among conflicting objectives.

This issue also includes two technical notes. The first describes a study by Estes and Frangopol to compare “Load Rating Versus Reliability Analysis” on a highway bridge. Advantages and concerns with both approaches are discussed. The second technical note reports on the “Improvement and Assessment of Neural Networks for Structural Response Prediction and Control.” Authored by Brown et al., this work proposes an improved approach wherein the Levenberg–Marquardt algorithm is used to train the neural network and a single neural network is used for more than one performance variable simultaneously. The issue concludes with Mottram’s “Discussion of ‘Local Buckling of Fiber-Reinforced Plastic Composite Structural Members with Open and Closed Cross Sections’ by Laszlo P. Kollar.” The original paper appeared in the November 2003 issue of the Journal. Equations developed and published by the discusser are outlined and compared to those presented in the original paper. The author of the original paper provides closure to the discussion by commenting on the applicability of the different equations.

Aristizabal-Ochoa, J. D., (2005). “Static stability of beam-columns under combined conservative and nonconservative end forces: effects of semi-rigid connections.” J. Eng. Mech., 131(5).

Asteris, P. G., and Syrmakezis, C. A., (2005). “Strength of unreinforced masonry walls under concentrated compression loads.” Pract. Period. Struct. Des. Constr., 10(2).

El-Tawil, S., Severino, E., and Fonseca, P., (2005). “Vehicle collision with bridge piers.” J. Bridge Eng., 10(3).

Kim, S. B., Spencer, B. F. Jr., and Yun, C.-B., (2005). “Frequency domain identification of MIMO systems considering physical relationships between measured variables.” J. Eng. Mech., 131(5).

Kuang, J. S., and Li, S., (2005). “Interaction-based design formulas for transfer beams: A box foundation analogy.” Pract. Period. Struct. Des. Constr., 10(2).

Li, J., Su, M., and Fan, L., (2005). “Vibration control of railway bridges under high-speed trains using multiple tuned mass dampers.” J. Bridge Eng., 10(3).

McDaniel, C. C., and Seible, F., (2005). “Influence of inelastic tower links on cable-supported bridge response.” J. Bridge Eng., 10(3).

Nair, Z., Aparna, K. M., Khandagale, R. S., and Gopalan, T. V., (2005). “Failure of $220\mathrm{kV}$ double circuit transmission line tower due to lightning.” J. Perform. Constr. Facil., 19(2).

Nguyen, T. X., Kim, B.-W., Jung, H.-J., and Lee, I.-W., (2005). “Improvement of eigensolution method for nonproportionally damped systems by step length.” J. Eng. Mech., 131(5).

Pearson, C., and Delatte, N., (2005). “Ronan Point apartment tower collapse and its effect on building codes.” J. Perform. Constr. Facil., 19(2).

Pisani, M. A., (2005). “Geometric nonlinearity and length of external tendons.” J. Bridge Eng., 10(3).

Pourzeynali, S., and Datta, T. K., (2005). “Reliability analysis of suspension bridges against fatigue failure from the gusting of wind.” J. Bridge Eng., 10(3).