- Presenters:
- Stephen Lucy
- Duration:
- 49 Minutes
- Format:
- Audio and Video
- License:
- Access for 6 month(s) after purchase.
- Short Description:
- Dallas City Hall and Plaza are recognized by many due to the opening scenes of Dallas, the television show. What is less known is that the structure is a significant early example of bonded post-tensioned concrete which was utilized throughout the superstructure and two-story parking garage constructed beneath the plaza. Opened in 1977, the parking garage is a two-way bonded post-tensioned concrete slab with unreinforced drop panels supported by flared circular concrete columns. The garage covers two city blocks, extends under two adjacent multi-lane streets, and supports mature landscaping, pool, fountain, and up to 11’-0” of soil. In 2017, several square feet of a drop panel fell from the structure and subsequent observations found multiple locations of drop panel and column capital failures. A structural investigation including destructive and non-destructive testing, and analysis of the existing structure was undertaken to determine the cause of the failures.
- Price:
- $15.00 - $25.00
- Presenters:
- Robert M Cordova | Mr. Richard First
- Duration:
- 30 Minutes
- Format:
- Audio and Video
- License:
- Access for 6 month(s) after purchase.
- Short Description:
- The Ituango dam is an embankment dam that is currently under construction on the Cauca River in Colombia. The largest hydroelectric power plant in Colombia’s history. Three large diversion tunnels used to divert the water from the river around the construction site during construction collapsed as a result of heavy rainfalls. The nearly completed pump house had to be flooded to accommodate premature water build-up in the reservoir. These tunnels would need to be permanently sealed. “Pre-stoppers” would need to be constructed in place to serve as bulk heads between which would ultimately be excavated and back-filled with concrete to permanently seal the tunnels. Additional to standard anti-washout properties, the grout had to withstand swiftly flowing water and exhibit an extended working time at temperatures above 32 degrees C. A custom grout was developed for this application. In the end, hundreds of grout micropiles were tremied, consuming more than 1,650 tons of grout, to produce...
- Price:
- $15.00 - $25.00
- Presenters:
- Dr. Farhad Habibi, PhD | Justin Breg, PhD
- Duration:
- 36 Minutes
- Format:
- Audio and Video
- License:
- Access for 6 month(s) after purchase.
- Short Description:
- Alkali-Silica Reaction (ASR) can cause significant damage to concrete structures including bridges, roadways, airport runways, and nuclear power plants. When reactive aggregates are included in a mix, the presence of moisture initiates a reaction between the alkaline cement paste and reactive amorphous silica. The result is a gel that continues to dilate, which may cause cracks in the concrete mass. A research program was undertaken at the University of Toronto to investigate the effects of ASR on large-scale and small-scale concrete specimens. Several specimens were constructed using reactive (ASR) concrete and non-reactive (regular) concrete, and their short-term and long-term structural and mechanical behavior were compared. In this presentation, we will discuss the results of the research program, will offer best practices to minimize the risk of ASR in concrete during placement, and will propose several strategies for repair of structures that have been degraded due to ASR.
- Price:
- $15.00 - $25.00
- Presenters:
- John Zhang
- Duration:
- 45 Minutes
- Format:
- Audio and Video
- License:
- Access for 6 month(s) after purchase.
- Short Description:
- Shotcrete has been used widely for rehabilitation and retrofit of concrete structures. More and more large infrastructures, in particular, in the hydro power industry, is using shotcrete for major rehabilitation and retrofit. Recently, the US Army Corps of Engineers has been engaged in structural modifications to reinforced concrete draft tube exits from the turbines in the Ice Harbor Lock and Dam located on the Snake River, Washington. This presentation details the structural modification to the draft tube which was successfully completed using wet-mix shotcrete.
- Price:
- $15.00 - $25.00
- Presenters:
- Alfred Gardiner
- Duration:
- 34 Minutes
- Format:
- Audio and Video
- License:
- Access for 6 month(s) after purchase.
- Short Description:
- Two projects will be explored in this presentation. The first is a concrete structure which for 20 years was exposed to extreme heat. The second is a structure which was exposed to extreme vibrations. Both these structures were integral parts of manufacturing processes and required limited down time to repair. The questions needing to be answered were: what is the condition of the existing concrete and what are the repair options for these structures. We turned to non-destructive techniques to evaluate these structures. Non-destructive techniques can provide insight into structures when accompanied by experienced engineers and petrographic analysis. Repair options were provided at the end of our evaluation leading to reduced down time and well-planned repairs.
- Price:
- $15.00 - $25.00
- Bundle:
- Fall Conference Bundle
- Presenters:
- Billy D. James, P.E.
- Duration:
- 22 Minutes
- Format:
- Audio and Video
- License:
- Access for 6 month(s) after purchase.
- Short Description:
- Post-tensioned concrete is a strong and durable material for construction of exposed parking structures. These types of structures are also fire resistant, but they can be damaged depending upon the severity of the fire. The structure in this presentation suffered significant fire damage early in its construction. The presentation will cover the discovery and testing methods used to determine the extent of fire damage, and the design of the repairs that were instituted to restore strength and allow construction to continue.
- Price:
- $15.00 - $25.00
- Presenters:
- Mike Tracy
- Duration:
- 43 Minutes
- Format:
- Audio and Video
- License:
- Access for 6 month(s) after purchase.
- Short Description:
- Increasingly, the Construction Industry is being dramatically impacted globally by internal and external forces. These influences range from acute labor and skill shortages, demographic and urbanization shifts, as well as, the Industry’s conversion from analog-based processes to digital workflows. This presentation will overview ten significant trends which are uniquely affecting the Construction Industry, creating both new challenges and opportunities, while transforming the Construction Industry.
- Price:
- $15.00 - $25.00
- Bundle:
- Fall Conference Bundle
- Presenters:
- Anirudh Goel | Mr. Charles Hammond
- Duration:
- 28 Minutes
- Format:
- Audio and Video
- License:
- Access for 6 month(s) after purchase.
- Short Description:
- The presentation, through case studies, talks about emergency response services for structural issues encountered during construction of new design projects. Among other examples is an eleven story precast parking structure. The contractor observed significant diagonal faulted cracking of L-beams (supporting double-tee sections) near bearing locations, few days after pouring topping slab. In addition, inverted-tee girders were observed to be supported on cracked corbels at other locations. A quick turn around was required to mitigate any immediate life safety hazard posed by the structural distresses and buy time for thorough investigation, non-destructive testing, analyses, and repair design. Another example is a seven story precast parking structure. The structure was under construction and reportedly erected out of plumb. Poor concrete placing practices and poor weld detailing led to widespread cracking in multiple structural elements throughout the structure...
- Price:
- $15.00 - $25.00
- Bundle:
- Fall Conference Bundle
- Presenters:
- Mr. Scott M. Greenhaus
- Duration:
- 1 hour
- Format:
- Audio and Video
- License:
- Access for 6 month(s) after purchase.
- Short Description:
- The iconic construction hard hat, a symbol of pride for the construction worker, has changed very little in 50 years. Developments in the understanding of the causes and prevention of debilitating and often fatal head injuries is leading to a revolutionary change in the way we protect our people from head injuries on the jobsite. The classic hard hat is about to change forever. This presentation will focus on new technology available today to minimize the effects of falls and impacts to the head of the worker. We will also focus on new technologies, already in development, that can further provide protection from head injuries. Industry requirements (OSHA, ANSI) will be reviewed, and the application of worldwide standards (EN) will be discussed and applied to new helmet development and implementation.
- Price:
- $15.00 - $25.00
- Bundle:
- Fall Conference Bundle
- Presenters:
- Nate Rende
- Duration:
- 37 Minutes
- Format:
- Audio and Video
- License:
- Access for 6 month(s) after purchase.
- Short Description:
- Nondestructive testing is often used in conjunction with traditional methods to assess construction, material, or structural deficiencies in new construction. This presentation describes evaluation of unique delamination failures within below-grade, exterior walls of a new subway station. The walls were conventionally reinforced mass concrete cast against a soldier pile and lagging retention system. Shortly after construction, leakage at cracks and joints was observed and injection processes led to delamination of the interior surfaces. The assessment objectives were to determine the extent and cause of near-surface discontinuities and evaluate the structural integrity of the walls. Nondestructive testing included flaw detection using Impulse Response [structural mobility testing] and reinforcement locating using ground-penetrating radar. Sampling and petrographic examinations were conducted to correlate test results with distress conditions and evaluate the in-situ concrete.
- Price:
- $15.00 - $25.00
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