After only six years of service, a 6-foot long narrow piece of concrete spalled off an exposed slab edge of a 680-foot tall high-rise in Texas, and fell 160 feet to the podium below. The spall was attributed to premature corrosion at the drip edge. The building featured approximately 9,200 feet of exposed slab edge over its height. Given the potential risk to safety and property of additional concrete spalls, the Owner requested forensic investigations, which (1) identified other areas with signs of similar distress and (2) determined the underlying problem of low reinforcement cover at the drip edge was pervasive. In response, repair options were developed to address the problem and restore intended durability. Given the building height, difficult exterior-only access, downtown environment, and post-tensioning anchors along the slab edge, the repair design and construction both had unique challenges to consider and overcome.
Using Unmanned Aerial Vehicles and Systems (aka UAVs aka Drones) continues to be a hot topic for engineers and designers. Within the past 10 years, we have seen technology change how we live, work, play and learn. These advances in technology have enabled humans to be more efficient as well as socially and environmentally conscious and connected. Advances in engineering technology and efficiency have expanded structural engineer’s roles in inspection services. This presentation will highlight drone utilization for exterior surveys and inspection, impact on the built environment, and how drones will continue to influence in the future. This includes areas that are too dangerous for humans or structures where rigging can be difficult or impossible as well as the cost benefits of using a drone. The presentation will also delve into the effectiveness and appropriate applications of drone usage, specifically for hands-on applications.
The application of nondestructive testing and evaluation for detecting existing defects and anomalies in concrete structures will be presented. Proper inspection and assessment is an integral part of a successful repair and rehabilitation. A well-defined inspection will help asset owners and their consultants in identifying the location and extent of existing defects, and enabling them in selecting proper repair materials and optimizing the area that needs rehabilitation. Moreover, NDT methods can help identify potential defects that are not visible to the naked eye, such as early-stage delamination, corrosion, and other durability related issues. In this presentation, several cases in Canada will be demonstrated, where the results of nondestructive testing and evaluation have been used to help consultants and contractors with cost-effective and reliable repair planning. Applications of ground penetrating radar, ultrasonic pulse echo tomography, seismic tomography, will be discussed.
The general sentiment around construction and modern technology is that the industry has been slow to embrace it. While this is true of the past, the current and future construction industry is all about modern technology. Not only does technology help to make the industry safer (something that has been a struggle for a very long time), but it is helping contractors to take back control of their budgets, to make smarter choices about project planning and equipment and is, consequently, pushing the green-construction trend forward. The purpose of this presentation is to provide a summary on the current technologies being used in the construction industry with a focus on concrete and to dig even further as to how these can be applied to repair projects. It will provide case studies on how using technology to bring ambient and concrete temperature, relative humidity and strength (among other) data online can help contractors be more efficient.
On August 9, 2019, Tyson Foods' Holcomb, Kansas beef plant experienced the first large fire in the meat processing industry in nearly 20 years. The long-burning fire precipitated the collapse of a portion of the high roof over the mechanical mezzanine, which housed equipment for numerous critical plant processes. This took portions of the plant, the second largest in the United States, out of operation for months. The pressures of substantial business interruption costs, as well as the market consequences for cattle feeders from the Southern Plains region, necessitated a rapid response. This presentation highlights the investigation into the extent of damage to precast members, including visual inspection, nondestructive and laboratory evaluations, testing, simulation, and analyses. Based on this investigation, members were identified for repair or removal and replacement.
Richard Miller Treatment Plant is a 240 mgd cap. potable water treatment facility located in the California area of the Cincinnati, Ohio, US. After installing an advanced ultraviolet (UV) disinfection treatment system in 2013, GCWW became the largest water utility in North America to use UV light following sand filtration and granular activated carbon. The concrete filter gallery building was originally constructed in 1907 with 26 filters, with a 14-filter addition in 1937 and 7 filters added in 1964. After over 110 years of service, the structures started showing significant signs of deterioration, most commonly concrete spalling and reinforcing steel corrosion. This case study will highlight the methods used to evaluate the structures that involved conventional methods such as sounding, crack mapping, chemical and petrographic examinations, along with technology such as Half-Cell Potential/ICOR, Impact-Echo, Ground Penetrating Radar, and UAS (Drone) services.
The prestressed beams in the Hampton Roads Bridge Tunnel Approach Spans were fabricated in about 1960 (west bound lane) and 1970 (east bound lane). The spans are 50-ft and 75-ft, respectively. The brackish water environment caused corrosion and failure of the bottom strands and deterioration and spalling of the cover concrete in many beams. A project in 2018 strengthened 30 of the more deteriorated beams as an alternative to posting or replacing the bridges. Carbon fiber composite wrap (CFCW) and external post-tensioning (PT) were used to strengthen the beams. Prior to construction, a PT mockup was done with one 50-ft (flexible filler) and one 75-ft (grout) beam to demonstrate that the contractor had the materials, equipment and staff to successfully do the external PT. This presentation describes the project’s mockups and construction and the anticipated increase in strength to be obtained from application of the CFCW and external PT.
Technology is not limited to innovative materials or equipment on a jobsite. Digital technology is changing how teams operate and is dramatically increasing efficiency and effectiveness. Cloud-based project management software allows key stakeholders to consolidate project data on to one mobile platform for easy collaboration. The entire project team, from general contractors, specialty contractors, owners, architects, engineers, conservators, and others can exchange data and documents with the tap of a screen. Communication between the field and the office is streamlined where everyone has access to real-time project details. This helps avoid duplicate entry errors and rework because teams built from an outdated drawing. In addition to drawings and details, project management software brings contracts, submittals, RFIs, billings, safety reporting, meeting minutes, photos, and financial reporting into one platform.
Arrowhead Stadium originally opened in 1972 and is known to be the home to the Super Bowl Champions Kansas City Chiefs. Renovations of the stadium completed in 2010 included adding luxury suites on the club level of the stadium. This meant that the upper seating bowl not only had to seat more than 34,000 Chief fans but also act as a "roof" for the new luxury suites. The upper seating bowl comprises L-shaped precast concrete seating risers spanning from cast-in-place concrete raker beams and is divided by sixteen expansion joints. In 2018, the planning for the upper seating bowl waterproofing program began. The goal for the repair project was to implement waterproofing upgrades to protect the concrete for the next 10 years. To add to the challenge of a large-scale waterproofing and structural repair project, the construction efforts had to include coordination with simultaneous seat replacement to be completed in a single off-season.
This presentation will look at how technology is used to perform condition assessments at height and in places with difficult access utilizing a virtual toolbox that includes a wide range of instruments and tools for non-destructive evaluation and testing, and a fleet of drones, each of which has a different use. The presentation will discuss how to use drones and tools at height; how the industry is using drones in new ways; and how some municipalities are changing policies to adapt, especially with regard to facade inspections.