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Structural Modeling of Stormceptors

The project consisted of the evaluation of as-built, cast-in-place, reinforced concrete for bottom tank sections of stormceptors at a highway bridge construction site in Puerto Rico. Quality control cylinders of the concrete from the vertical walls, base, and floor of the tank sections were tested and indicated low compressive strengths which caused concern for the structures’ ability to resist the design loading conditions. CA performed an investigation of the design and as-built condition of the stormceptors which included, among others things, a review of product data sheets, construction related plans and drawings, applicable industry standards, and conducting a finite element structural analysis that modeled each structure’s geometry under different load conditions. By conducting finite element structural analysis, CA was able to compare each structure’s load carrying capacity with that required for design, for both flexure and shear. CA’s investigation concluded that the as-built structural capacity was sufficient considering the lowest compressive strength in each stormceptor.

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Corrosion of Steel Chimney

The owners of a steel smokestack expressed concerns over the amount of steel corrosion and resulting loss of cross sectional area as well as concerns over the large amount of cracking in the smokestack’s cast-in-place concrete foundation. CA investigated the structural integrity of the concrete foundation and smokestack and provided recommendations for their repair and remediation. CA performed an assessment of the condition of the concrete foundation and smokestack including site inspection, non-destructive testing services such as ground penetrating radar scanning and ultrasonic thickness scanning, concrete coring, petrographic examination, and structural analysis and design. CA’s investigation determined that the smokestack had lost close to 40% of its cross section in certain areas. Based on the investigation, CA developed recommendations for restoring the structural integrity of the smokestack by remediating the wall thickness in several areas and repairing the concrete cracking.

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Litigation Support for Masonry Brick Screenwalls

This project consisted of conducting an investigation into the cause(s) of the observed deterioration of brick perimeter screenwalls in North Texas. The brick masonry units were imported into the United States. Distress observed included cracking, crumbling, deterioration, fading color, and warping. Among the areas investigated were the manufacturing processes, quality control, and adequacy of the specification requirements for the masonry units for their intended purpose. Findings from testing performed indicated that the masonry units did not meet the requirements for durability in a North Texas environment. Among other causes, the firing process during manufacturing most likely affected the durability and performance of the brick in service. CA served as an expert witness, indicating that lack of understanding, confusion, and relaxed implementation of the industry standards for materials in the masonry structures contributed to problems in certifying the quality of the bricks.

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Construction Consulting for the San Roque Dam and Reservoir

Located in the Island of Luzon on the Agno River, approximately 200 km from Manila in the Philippines, this dam and reservoir project intended to produce non-polluting, hydroelectric power, provide water irrigation, reduce downstream flooding, and improve water quality in the San Roque River. The project included a 200-meter-high rock fill dam to be the twelfth highest embankment dam in the world. CA provided construction troubleshooting services and recommendations for concrete mixture proportions, concrete production, and concrete placement and finishing for the casting of mass concrete sections utilizing high performance concrete for the concrete spillway and tunnel sections. Among the challenges being faced was the production of concrete to be placed on very steep slopes and long tunnel sections while achieving a smooth finish with reduced cracking to resist the forces of high water flows. CA was also involved in developing repair recommendations for the rehabilitation of some of the concrete already in place.

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Forensic Pavement Analysis of a Parking Lot

The forensic investigation for this project consisted of sampling, testing, and evaluating the pavement structure including base, sub-base, and natural soil materials, and determining the cause(s) of the observed distress of the parking lot at the Redstone Golf Course in Humble, Texas. Distress in the parking lot was mainly in the form of cracking with isolated heaving and bulging at several locations. CA performed a detailed condition assessment including coring and excavations to sample, document, and evaluate the pavement system. Destructive testing included petrographic examination and chemical and mineralogical analysis of the different materials comprising the pavement system, natural soil, stabilized subgrade, and selected materials. Further, CA’s forensic investigation included, among other things, evaluating the construction practices, quality control testing, and the overall drainage and landscaping design for the site.

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NDT Services at a Distribution Center Concrete Pavement Parking Lot

CA conducted an investigation to determine the cause(s) of the distress in the exterior concrete pavement at a distribution center facility in Houston, Texas. The investigation consisted of a comprehensive assessment of the structural integrity of the pavement using destructive and non-destructive testing evaluation techniques as well as the excavation of pits for geotechnical exploration and testing in order to evaluate the as-built soil stabilization methods. Non-destructive testing services provided on this project included ground penetrating radar scanning and relative elevation surveying. Other activities included the evaluation of the original concrete pavement design and assumptions, performance of a life cycle analysis, performance of service life calculations given the actual usage of the pavement, and review of construction related issues. CA also developed recommendations for the repair and remediation of the concrete pavement system.

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Forensic Engineering Investigation of Precast / Prestressed Railroad Ties

CA conducted an extensive forensic engineering investigation into the cause of premature distress of thousands of precast/prestressed concrete railroad ties in service along numerous railroad lines primarily in the northern part of the United States. The forensic investigation included performing a comprehensive condition survey to characterize and assess the extent of the distress, sampling and testing to determine the internal distress mechanism causing the early deterioration of the railroad ties, and identifying the factors affecting the progress of the distress mechanism. The investigation included a detailed review and evaluation of the concrete production, materials, mixture proportions, quality control and curing practices, effect of the distress on the structural adequacy of the ties, distress documentation, non-destructive evaluation, mineralogical and chemical analysis of alkali aggregate reaction, and petrographic examination, among others. This investigation included several potential distress mechanisms including delayed ettringite formation (DEF), alkali-silica reaction (ASR), and freeze-thaw damage.

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Seismic Analysis and Design Review of a Power Plant Chimney

A 460 ft. tall reinforced concrete chimney for a power plant was designed under strict loading parameters including the effects of seismic forces. CA was asked to review the design of the chimney to assure it had been designed for the appropriate loads including seismic, wind, and dead loads. CA performed a finite element analysis of the chimney to determine the in-service stresses experienced by the chimney for various load combinations. Furthermore, CA reviewed the original and as-built plans and drawings, original design calculations, and analyzed the design procedure. CA determined the appropriate design procedure and loading conditions and assessed the addition of structural fiber reinforced polymer reinforcement to the as-built structure to provide supplemental stability and capacity.

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Repair and Rehabilitation of a Post-Tensioned Parking Garage

A two story, cast-in-place post-tensioned concrete parking garage cut into the side of a slope provided a parking area and structural support for a major grocery store. The second floor of the parking garage was level with the surface parking area adjacent to and in front of the grocery store. Issues investigated were related to water intrusion, concrete cracking, foundation performance, retaining wing wall movement, loss of subgrade support, jointing, construction defects, moisture management, and performance of the post-tensioned beams.  These issues were investigated to determine any possible impacts on the long-term performance of the structure. CA performed, among other things, a detailed condition assessment of the structure, review of construction related documents, drawings, and plans, and a structural analysis and evaluation of the post-tensioned structure. CA successfully determined the causes of the concerns and developed recommendations for repair and rehabilitation of the structure to restore its performance.

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Construction Defects at a Multifamily Residential Building

CA performed a forensic engineering investigation of 15 buildings in a multifamily residential complex to investigate alleged construction defects. Among the many concerns investigated were the construction of the roofs, exterior walls, floors, building envelope related problems, air quality issues including moisture penetration and mold growth, and water induced deterioration of building materials. The overall investigation included, among other things, performing a survey to assess the existing condition of the structures, water testing at selected locations in the envelope of the buildings including exterior walls and balconies, testing of the HVAC systems, air quality testing for mold, material sampling, and moisture content determinations of building exterior areas.