EDITOR’S NOTE

This issue starts with a group of papers on masonry construction. Other papers and technical notes in the issue address a variety of topics, including the reliability of reinforced concrete structures, fiber-reinforced concrete and cementitious composites, structural analysis and behavior, behavior of cold formed steel members, optimization, and timber structures.

The issue opens with two companion papers titled “Dynamic Behavior of a Medieval Masonry Bell Tower: Parts I and II” by Bennati et al. The authors report on the results of an ongoing research project investigating the dynamic response of the bell tower of the Cathedral of San Miniato in Pisa, Italy. The papers describe experiments that were performed to characterize the dynamic behavior of the tower, its bells, and the interaction among them. Analytical and numerical models are used to interpret and complement the experimental results.

In “Dry Joint Stone Masonry Walls Subjected to In-Plane Combined Loading,” Lourenco et al. present the results of experimental research on the structural behavior of dry joint masonry walls subjected to in-plane combined compressive and shear loading. The authors describe and comment on the relationship between the observed structural response and the results of numerical modeling. A simplified diagonal strut model is proposed on the basis of the data developed in the research.

Two papers focus on corrosion of reinforced concrete (RC) structures. The first paper “Time Dependent Reliability Method to Assess the Serviceability of Corrosion-Affected Concrete Structures,” written by Li et al., describes a performance-based methodology for serviceability assessment of corrosion-affected RC structures. An advantage of the developed method is that it utilizes parameters that are commonly used by design engineers and asset managers. The authors assert that time-dependent serviceability methods such as the proposed technique serve as a useful tool for managing inventories of corrosion-vulnerable concrete structures. The second paper on corrosion is by Vu and Stewart and is titled “Predicting the Likelihood and Extent of RC Corrosion-Induced Cracking.” In the paper, the authors describe a two-dimensional time-dependent reliability model to predict corrosion-induced cracking as a function of concrete cover, compressive strength of concrete, and surface chloride concentration. The model, which is suitable for predicting crack widths up to 1 mm, is applied to a typical RC bridge deck. The authors suggest that when combined with life-cycle cost analysis, the proposed model can serve as a useful tool to predict future repair costs and to determine optimal maintenance strategies.

In “Bond-Slip in Reinforced Concrete Elements,” Luccioni et al. propose a bond-slip model for reinforced concrete. The model is formulated within the framework of plasticity theory and the theory of mixtures. In the proposed model, an RC structure is considered to consist of a matrix (i.e., concrete) and fibers (i.e., rebars), whose response is modified to account for the relative displacement between the two phases. The authors use a previously proposed elastoplastic model to describe the interface between steel and concrete. The formulation accounts for the effect of confinement pressure, surface pattern of rebars, and dilation of the adhesion zone and associated cracking. The model is particularly advantageous for macroscale analyses, since explicit discretization of rebars and the interface is not required. The authors validate the model through comparisons with experimental data. A second paper dealing with bond in concrete structures is “Splitting Bond Capacities of Concrete Element Reinforced with Continuous Fiber” by Iihoshi et al. Unlike the previous paper, which dealt with reinforced concrete, this paper addresses concrete structures reinforced with steel rebars and continuous polyacetal fibers (PAF) that are at the same time externally wrapped with PAF to improve confinement. On the basis of an experimental investigation, the authors indicate that the bond capacity improves because of the presence of PAF. An equation for predicting behavior as a function of the quantity of PAF is proposed.

In “Investigation of Infill Panels Made from Engineered Cementitious Composites for Seismic Strengthening and Retrofit,” Kesner and Billington describe a retrofit strategy for critical facilities that uses an infill system consisting of ductile engineered cementitious composites (ECC). The authors conducted finite element simulations to determine the optimum geometry of the infill panels. A series of structural scale tests were conducted by using the developed geometry. The tests demonstrate the potential of the infill system as a retrofit scheme and show that different levels of infill panel strength and stiffness can be achieved by varying the ECC mix design and the amount of steel reinforcement in the panel.

Transitioning from concrete-related papers to steel papers is “Numerical Analysis of Composite Steel-Concrete Columns of Arbitrary Cross-Section” by Marques de Sousa and Caldas. The authors present a numerical formulation for nonlinear analysis of slender composite columns of generic cross sections subjected to axial force and biaxial bending. The cross section is treated as a number of closed polygonal loops, each with its own stress-strain relation and embedded reinforcement. Displacement-based beam-column elements are used to represent member behavior. The proposed model is validated against existing experimental data and is shown to perform well. In “Flexural-Torsional Buckling of Columns with Oblique Eccentric Restraints,” Trahair and Rasmussen discuss elastic flexural-torsional buckling of eccentrically loaded columns with oblique eccentric restraints, which can resist various combinations of deflection, flexural rotation, twist rotation, and warping. Buckling of a column with such restraints involves biaxial bending and torsion. The authors discuss the nature of oblique restraints, summarize finite element analyses that they conducted, present examples of behavior, and demonstrate the design of columns with oblique eccentric restraints. The last paper on steel structures is “Behavior of Cold-Formed High Strength Stainless Steel Sections” by Young and Lui. The authors conducted tests on square and rectangular stub-length specimens that were cold-rolled from flat strips of duplex and high-strength austenitic stainless steel. Measured stress-strain response, residual stresses, and geometric imperfection data are presented; and the strengths of the stub columns are compared with the design strengths predicted by several specifications.

In “Optimization Methodology for Damper Configuration Based on Building Performance Indices,” Liu et al. present a design methodology to optimize placement of energy dissipation devices on the basis of building performance objectives. The proposed strategy combines engineering knowledge and an iterative approach to optimize the configuration. The optimization strategy involves minimizing various commonly used performance indexes. By using two case study buildings, the proposed method is compared with other techniques and is shown to be capable of effectively reaching an optimal configuration.

The last two papers deal with timber structures. In “Modeling Timber Moment Connection under Reversed Cyclic Loading,” Chui and Li address the behavior of moment-resisting timber connections containing mechanical fasteners. a previously developed single-fastener finite element model was used to develope a model to predict the moment-rotation behavior of timber connection containing several fasteners subjected to reversed cyclic loading. The model is validated through comparisons with test data and is shown to perform well. In the last paper, “Fragility Analysis for Performance-Based Seismic Design of Engineered Wood Shearwalls,” Kim and Rosowsky investigate the application of fragility techniques to the seismic design of engineered woodframe shear walls. The authors treat woodframe shear walls as isolated subassemblies and use nonlinear dynamic time history analysis to investigate seismic performance. On the basis of their studies, the authors found that wood shear walls designed to meet 1997 UBC requirements exhibit similar levels of performance for all nailing schedules addressed in the code. They indicate that the fragility procedure that they developed offers an approach for evaluating the response modification factor $\left(R\right)$ for wood shear walls acting as part of a complete structure. Furthermore, the authors suggest that the methodology that they propose can serve as a basis for developing future performance-based seismic design specifications for engineered woodframe shear walls.

The issue concludes with two technical notes. The first article is “Empirical Punching Shear Failure Theory for Oriented Strand Boards: Preliminary Study” by Thomas and Noldred. The authors use punching strength models for concrete to develop empirical equations for the punching strength of oriented strand boards. The proposed punching model appears to correlate reasonably well with experimental results for the prototypes discussed in the paper. The authors indicate that additional tests are needed to develop generally applicable models. The second technical note is titled “Assessment of Shear Deformations on the Seismic Response of Asymmetric Shear Wall Buildings” and is by Tena-Colunga and Perez-Osornio. In the note, the authors assert that analysis of shear wall systems should include the effect of shear deformations in addition to flexural deformations. They show that for specific situations, considering the wall shear flexibility influences important design variables and affects the relative distribution of shear forces.