The American Lumber Standard Committee (ALSC) Board of Review approved changes to design values for all grades and all sizes of visually-graded Southern Pine and Mixed Southern Pine lumber, with a recommended effective date of June 1, 2013 to allow for their orderly implementation. …
Many existing structures in North America experience ongoing moisture intrusion and resulting decay that significantly compromises the integrity of wood members. If left unmitigated, advanced decay in wood members supporting roofs, exterior walls, deck assemblies and floor systems can and does impair the capacity of these elements to support code-prescribed loads. …
A few weeks ago, I met with new employees of our firm to introduce our risk management program to them. It is one of my duties as the risk management director for our office. Because of the economic downturn, I had not had the opportunity to make this presentation for a while, and it felt good to be able to do one again. As I was preparing for this presentation, I had the opportunity to consider risk management and how it really requires that your firm have a culture of risk management. A culture of risk management is the first of CASE’s Ten Foundations of Risk Management. It is not something that can only be touched on occasionally, but must be a constant presence in the design process. …
A crossing of the Schuylkill River on the extension of Market (Formerly High) Street in Philadelphia had been a pressing need for many years when, in 1723, an act was passed entitled “An Act for establishing a ferry over the river Schuylkill, at the end of the High Street of Philadelphia.” In 1767, a bridge over the river at the Middle Ferry was first proposed. …
Bridge deflection and vibration data are often useful for structural health monitoring (SHM), load rating determination, change in use, or retrofitting. Deflection and vibration data are typically gathered through nondestructive testing (NDT) or nondestructive evaluation (NDE) methods. For most bridges, this means installing accelerometers, strain-gauges, linear variable differential transformer (LVDT), or string pot type instrumentation, which sometimes requires a temporary restriction of bridge use, and technicians must gain access to the bridge’s structural members which can involve fairly hazardous work, both to install the instruments and to remove them when the study is complete. …
The art of bridge design is a time-honored pursuit that, throughout the centuries, has undergone significant advances in engineering and technology as a result of mankind’s passion to conquer the challenges of any given crossing. It has evolved through the acceptance of well-established practices, codes and construction techniques. In fact, when new materials or methodologies are brought to the market, it often takes many years for the techniques to gain inclusion in the modern practice of bridge design. …
For most of us, our training as structural engineers has included significant attention toward transient seismic events. They can have such destructive potential as to occupy a major role in the geometry, design and detailing of our projects. For decades, prescriptive methods in codes have predicated design around a peak transient condition that presumably produces a peak base shear reaction and a peak rooftop displacement. These phenomena then become the basis of criteria for the seismic design. …
Structural Forum is intended to stimulate thoughtful dialogue and debate among structural engineers and other participants in the design and construction process. Any opinions expressed in Structural Forum are those of the author(s) and do not necessarily reflect the views of NCSEA, CASE, SEI, C3Ink, or the STRUCTURE® magazine Editorial Board.
A short time ago, I started working on a project that will be designed for construction in Europe. As such, I decided that I ought to know European construction law. …
T.Y. Lin International was an Outstanding Award Winner for the Harbor Drive Pedestrian Bridge project in the 2012 NCSEA Annual Excellence in Structural Engineering awards program (Category – New Bridge & Transportation Structures).
The Harbor Drive Pedestrian Bridge in San Diego, California, is located in the downtown area of the city near San Diego Bay. …
Disproportionate collapse of structures continues to be an exciting topic in structural engineering, given its public safety implications, philosophical aspects, technical challenges, and opportunities for designers to expand their technical skills while proposing unique solutions. Research is actively underway in the US and many other countries, in both university and government laboratories, and technical sessions on disproportionate collapse at recent Structures Congresses have been lively and well-attended. …