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.
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...
This video will illustrate an example of how various sections of ACI 562 are applied in the execution of a complex repair project, the repurposing of a historic train deck into a transportation hub for light rail trains and busses. Methods of evaluation and analysis, as guided by ACI 562, will be presented with a discussion of how these provisions lead to various repair approaches presented to the owner.
This video will discuss how the requirements of ACI 562-16 are used in the evaluation and repair of parking structures. It will take participants through a representative garage project, utilizing Design Example 1 from the Guide to the Use of ACI 562 as the basis. Evaluation and design considerations will be discussed relative to the Repair Code as well as QA/QC and the Engineers' Role during construction.
This video will illustrate an example of how various sections of ACI 562 are applied in the execution of a Precast/Prestressed Double-Tee repair project. Methods of evaluation and analysis, as guided by ACI 562, will be presented with a discussion of how these provisions can lead to various repair approaches.
Codes and standards are developed for use by design professionals; however, the use of codes and standards significantly impacts Owners and Contractors. The ACI 562 code was motivated by the poor performance of repaired concrete structures, specifically premature failure of repairs and limited durability of repaired structures. Development of the code was intended to benefit owners and contractors by improving performance and perceptions regarding repairs to existing structures.
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.
The case-histories based presentation will focus on the use of nondestructive evaluation (NDE) methods to detect flaws and damage in concrete construction. Case histories will be presented for detection and mapping of flaws and damage in concrete such as cracking, delamination, honeycomb, void, corrosion, fire damage, alkali-silica reaction and low strength concrete. The case histories for the concrete structures are anticipated to include parking structures, bridges, buildings and dams. NDE methods will include sonic/ultrasonic, infrared thermography, radar and corrosion technologies where the results in many cases were confirmed by coring. The use of some of the NDE methods for QA of concrete repairs such as epoxy injection and patching will also be discussed.
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.
Concrete is the most widely used construction material and can be durable for hundreds of years; however, the main cause of concrete deterioration is from corrosion of reinforcing steel. Steel is thermodynamically unstable and will eventually oxidize to a lower energy state. The rate of deterioration in new and existing structures can be modeled to predict the service life based on the severity of the service environment, the concrete quality, the ingress of deleterious materials, and other factors to various degrees of success. This presentation will provide an overview of many of the service life models currently in use and provide an evaluation protocol for their application related to both new and existing structures.