As concrete structures begin to age and deteriorate, the need to understand corrosion behavior is pertinent to determining where a structure is in its life cycle. One of the most successful methods of determining the corrosion rate of embedded steels is the Linear Polarization Resistance (LPR) method. The results of this test method provide measurements of corrosion current (Icorr,) or corrosion penetration rates. …
Recent fatalities associated with failed structural building elements have generated discussion about actual causation and whether building code changes are required. These failures have also increased the demand for architectural and structural inspections on similar existing elements.
The authors are consultants who frequently forensically diagnose alleged construction defect claims. Clients are typically developers, designers, contractors, insurance agencies, attorneys, manufacturers or building owners. This background provides a unique perspective on the relative risk to the structural engineer. …
In 1838, an arsonist burned Lewis Wernwag’s Colossus Bridge (STRUCTURE, June 2014) over the Schuylkill River near Philadelphia. Its 340-foot main span was, at the time, the longest single span bridge in the United States. Charles Ellet, Jr. (STRUCTURE, October 2006) immediately proposed replacing it with a wire cable suspension bridge. By this time, several Finley Chain Bridges were built in the Philadelphia area as well as a short lived, long-but-extremely-narrow, pedestrian wire bridge across the Schuylkill River built by Josiah White and Erskine Hazard. …
In the design of concrete structures, where concrete slabs and walls are used as the environmental barrier, water leakage is a concern. In well consolidated, normal weight concrete, high pH components within the cement/gel paste react with iron on the steel surface and resist corrosion from actively occurring around the steel. This is called “passivation.” …
By definition, innovative means “tending to innovate or introduce something new or different”. Within the context of the International Building Code (IBC), Section 104.11 Alternative materials, design and methods of construction and equipment provides a mechanism for how building officials can approve innovative, new or alternative building materials, design and methods of construction that are not adequately addressed in the code. …
The April 2014 issue of STRUCTURE magazine featured an article in the Structural Failures column, titled Design Deficiencies in Edge Barrier Walls in Parking Structures, by Mohammad Iqbal, D.Sc., P.E., S.E., Esq. The article brought up important points related to the adequacy of upturned cast-in-place (CIP) concrete barrier walls supported on slab edges to withstand code-prescribed vehicle barrier loads in parking structures. …
Structural Engineering is an evolving field. Our profession continues to innovate with brilliant new technology, materials, and analysis methods, at an ever increasing pace. I can remember when I started as a junior structural engineer in 1983, the introduction of personal computers was just beginning to take place, along with the finite element method for structural analysis. This was a significant step forward from the previous generation of engineers who grew up on slide rules. After 33 years, I’m still learning. …
The American Concrete Institute (ACI) published the Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14) in the Fall of 2014. ACI 318-14 has been adopted by reference into the 2015 International Building Code (IBC). Adoption of the 2015 IBC by cities, counties, and states has been rather slow. However, major adoptions are scheduled to follow. …
Leslie E. Robertson Associates was an Outstanding Award Winner for the Columbia University Medical Center Graduate Education Building project in the 2015 NCSEA Annual Excellence in Structural Engineering awards program (Category – New Buildings $30M to $100M).
The Columbia University Medical and Graduate Education Building (CUMGEB) is a 100,000 square-foot, 15-story, state-of-the-art medical education facility, whose multifaceted goals include the linking of students and teachers, of interdisciplinary study and interactive learning, and of function and experience, all while providing an identity and focal point for Columbia University’s Washington Heights campus. …
I believe that the majority of Americans understand the need for some kind of building code to regulate construction. Millennia ago, Hammurabi gave us the “eye-for-an-eye” version of the building code. Since the Chicago fire of 1871 and the San Francisco earthquake of 1906, there have been building codes in America. …