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Prestressed Concrete Bridge Girders

Part 2

This is the second of two articles discussing high-level design considerations of prestressed concrete girders. Part 1 (STRUCTURE, January 2021) provided an overview of the post-tensioning and pretensioning processes, described the common materials used in constructing prestressed bridge girders and discussed the time-dependent prestress losses inherent in their design. The discussion continues in Part 2 with fundamental design considerations for internal stress distributions within prestressed concrete girders and the methodology for application.

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Apr, 2021 By Dustin Black In Structural Rehabilitation Comments 0

Underwater Weld Repairs

Due to damage or deterioration, structures, infrastructures, and even vehicles may require in-situ repairs and modifications. This is true for structures that are on land but also for those underwater. Piers in ports deteriorate or get damaged by impact or operations over time, and ships and vessels require maintenance and repairs below the waterline.

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Apr, 2021 By Uwe W. Aschemeier, Axel Mutzeck, Kevin S. Peters and Jarrad A. Schmerl In Structural Repair Comments 0

Which Post-Tensioning Tendon?

Which End to Stress First?

In post-tensioned floors, tendons are stressed after cast concrete gains adequate strength. The stressing operation is monitored to ensure that tendons receive their design-intended force.

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Apr, 2021 By Bijan O. Aalami, S.E., Ph.D., C.Eng. In Construction Issues Comments 2

Error Checking and the Black Box

Part 1

The “black box.” We have all heard the phrase, maybe to the point of nauseum. By necessity, as code requirements continue their evolution into ever-increasing complexity, we depend more and more on software to do the calculations that some of us and our predecessors used to do by hand. Not only can the intimate knowledge of how to run the calculation be lost in this trade-off, that move from pencil, paper, and calculator (or slide rule!) to computer software, the old-fashioned “gut feeling” can be lost as well. Unfortunately, these essential tools of the wise engineer are quickly disappearing from our profession.

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Apr, 2021 By Scott N. Jones, S.E. In Engineer's Notebook Comments 2

Reducing Potential Liability in Emergency Response

Architects and engineers have become more reluctant to render services over the last 20+ years in response to disaster emergencies out of fear of liability exposure. Before doing so, A/E professionals should ensure that their actions do not present a liability disaster to themselves and their firms. This article briefly reviews lessons learned in the aftermath of emergency responses by the A/E community and addresses ways that A/E professionals can manage risk to continue providing vital emergency response services.

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Apr, 2021 By Melissa T. Billig, Esq. and Maurizio Anglani, Esq. In InSights Comments 0

A Few Things Young Engineers Should Know!

Having graduated from college into my first job as an engineer a mere 45 years ago, I experienced the things I write about here. Although not easy, I am happy to say that I still love to come in to work and perform engineering. I have worked for four Companies over my career, all good Companies. I started with an ENR Top 10 Engineering firm and have moved to smaller and, for me, more intimate Companies each time I took a new position. I felt that by working for smaller companies, my contributions would have more impact on my clients. Here are a few things that served me well as I began my career and have held up as I advise young engineers on traditional structural engineering career paths. This article was initially prepared and delivered to Dr. Joseph M. Plecnik’s Professional Practices Class (CE481) at California State University, Long Beach, in March 2007 and has been updated for publication here. Dr. Plecnik was the author’s favorite Professor at CSULB.

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Apr, 2021 By Steven G. Provenghi, S.E., M.ASCE In Structural Forum Comments 0

Design Strategies for 3-D Volumetric Construction for Concrete

Three-dimensional (3-D) volumetric construction is also known as concrete modular construction or Prefabricated Prefinished Volumetric Construction (PPVC). This construction method involves the stacking of rectangular factory-finished modular components on-site to form a complete building, similar to Lego® bricks. Joints are typically grouted with special interfacing details. To achieve speed and high productivity, the components have to be substantially completed with minimal site work. This article looks at some of the key design considerations and strategies that designers need to think about when using this type of construction method.

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Apr, 2021 By Hee Yang Ng, MIStructE, C.Eng, P.E. In Structural Design Comments 0

Creating an Icon

The Dublin Link Pedestrian Bridge

The Dublin Link was designed to create an iconic destination for Dublin, Ohio, activate the Scioto River corridor, and literally tie together the Eastern and Western sides of the city. The formal aesthetic and structural methods were developed simultaneously to create a single coherent vision. The resulting bridge is the longest single-sided suspension S-curve bridge in the world. It is supported by an expressive central pylon that the bridge deck passes through, conceptualized as the gateway between the historic town center and the newly developed mixed-use district on the East bank. The form and arrangement of the tower and bridge cross-section were developed through theoretical stress-shaping and refined through digitally-driven optimization.

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Apr, 2021 By STRUCTURE magazine In Spotlight Comments 0

Learning and Leading into the Future

Wow! COVID-19 and the challenges of 2020 have come out for an encore at the start of 2021. (I am writing this in January for publication in March.) Hopefully, this will be the only encore, and we will soon realize widespread vaccination against COVID-19 for movement toward a new normal for our businesses and livelihoods. …

Mar, 2021 By Joseph G. DiPompeo, P.E., F.SEI, F.ASCE In Editorial Comments 1

The Economics of Seismic Strengthening

Reconsidering Costs in Areas of Lower Seismicity

The economics of reducing seismic risk has generally received less attention in regions of lower seismicity than in higher-risk regions of the country. Though less heralded, the subject is important: what investment in risk reduction is appropriate to the extant risk? …

Mar, 2021 By Terrence F. Paret, Gwenyth R. Searer, Kari Klaboe, P.E., S.E. and Hayley Proctor, P.E. In Structural Economics Comments 0

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Part 2

Which End to Stress First?

Part 1

The Dublin Link Pedestrian Bridge

Reconsidering Costs in Areas of Lower Seismicity