Editor’s Note

The February 2012 issue of the Practice Periodical on Structural Design and Construction contains four papers and a forum. These papers cover a diverse set of topics, each focusing on an interesting and informative practical area pertinent to design and construction. The variety of topics covered in this issue will appeal to a wide group of readers involved in structural and construction practices. In addition to these four papers, a forum is also included in this issue, covering a timely topic of particular interest to practicing engineers.

The forum in this issue is entitled “Hidden Brick Bond” and was prepared by John Springfield, a forum editor. It discusses the absence of headers in exterior brick walls in older buildings and the methods (or lack) of tying the separate wythes, such as brick veneer and concrete blocks. Fig. 1 shows a building without an exposed header and displaced bricks.

The first paper in this issue is entitled “Analytical Investigation of Potential Seismic Damage to a Skewed Bridge.” The paper was prepared by Piboon Apirakvorapinit of AON Insurance Company, and Jamshid Mohammadi and Jay Shen of the Illinois Institute of Technology. This paper examines the damage that occurred to a skewed bridge (the Pico-Lyons Bridge in Newhall, California) after the 1994 Northridge earthquake. A nonlinear finite-element method was used to further investigate the damage. The findings of this study, along with recommendations geared specifically to skewed bridges, are summarized in this paper. Fig. 2 shows the investigated Pico-Lyons skewed bridge with four girders and bearing locations at the center pier and the abutments.

The second paper, entitled “Seismic Base Isolation for Buildings in Regions of Low to Moderate Seismicity: Practical Alternative Design,” was prepared by A. B. M. Saiful Islam of the University of Malaya, Syed Ishtiaq Ahmad of Bangladesh University of Engineering and Technology, and Mohammed Jameel and Mohd Jumaat Zamin, also of the University of Malaya. This paper covers the design of seismic base isolators for a building located in Dhaka, Bangladesh. Analyses have been carried out for both isolated and nonisolated buildings, also considering buildings with different heights. Fig. 3 shows the base isolator used to isolate the superstructure from the substructure.

The third paper, “Laterally Loaded Reinforced Concrete Stiffened Plates: Analytical Investigations,” by Harvinder Singh of Guru Nanak Dev Engineering College, India, presents an analytical model used to predict the collapse load and corresponding failure mode of a stiffened rectangular reinforced concrete plate. Fig. 4 shows the stiffening beams and the yield lines.

Ali Akbar Gholampour and Mehdi Ghassemieh of the University of Tehran prepared the fourth paper in this issue. It is entitled “New Practical Approach to Nonlinear Dynamic Analysis of Structures: Refinement of Classical Newmark’s and Wilson’s Methods.” The paper proposes a new direct time integration method of nonlinear structural dynamic problems. The results obtained from this method are then compared with Wilson’s and Newmark’s methods. Fig. 5 shows a tower supporting a tank of mass $M$. This is one of the examples used in the paper to compare the results of the proposed method with other existing implicit methods

The Editorial Board thanks the authors of this issue’s papers. Readers are invited to submit comments or questions on any of these papers as discussions and are also invited to introduce their experience pertaining to the topics of these papers or present alternative opinions and views. Discussions or questions should be submitted as stipulated in the “General Information” section, which can be found at the front of this periodical.