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Port of Valdez Marine Terminal Condition Assessment and Cost Analysis

This project involved the condition survey and life-cycle assessment of the three process facilities related to the ballast water treatment at the Valdez Marine Terminal located in Valdez, Alaska. CA conducted an on-site condition survey of the Gravity Separator Tanks, the Dissolved Air Flotation Facility, and the Biological Treatment Tanks, all of which exhibited evidence of significant deterioration. The condition assessment study included documentation of the distress present in the concrete substructures and structural steel superstructures of the three facilities including concrete non-destructive testing and concrete sampling. Concrete samples for chloride ion content testing, petrographic analysis, and corrosion testing were extracted and existing data from in-place cathodic protection systems was evaluated. Recommendations for structural repair and remediation related to the present condition and future serviceability of the facilities were prepared and a rehabilitation construction cost analysis was presented.

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Steel Frame Structure

CA’s investigation consisted of determining the cause(s) of the alleged distress and excessive movement in the storage yard overhead crane system at two of the facilities in Ghent, Kentucky and Decatur, Alabama. A comprehensive condition assessment, geotechnical exploration, surveying, and structural analysis of the structure were performed including a review of the structural design, foundation design, erection sequence, and construction documents. CA’s investigation determined the cause of the distress and led to the development of alternatives for the remediation of the facility for its intended use.

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Concrete Materials Consulting for San Juan’s Rapid Urban Train System

This $1.7 billion, 17.3 km mass transit system aimed to alleviate the traffic congestion in San Juan, the most densely populated city in Puerto Rico. It included both underground and elevated rail sections and multiple stations. Tunneling was performed below the water table near the ocean in a Zone IV seismic area. Some of the major challenges involved the casting of massive concrete sections underground as well as the design of precast concrete tunnel sections with special concrete mixtures, all of which were attained with innovative use of admixtures and supplementary cementitious materials as well as optimized concrete production techniques. CA provided consulting services regarding the conformance with specifications, concrete mixture proportions, concrete production, placement of concrete, curing techniques, concrete durability, quality control, and quality assurance during construction. In addition, the structural strengthening of the columns supporting the elevated sections of the rail to meet seismic Category IV design criteria in portions of the structure already built posed a major challenge, which was addressed with novel and innovative methodologies including, but not limited to, fiber reinforced polymer wrapping.

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Tilt-Up Construction Collapse Failure Analysis

A two story, tilt-up construction commercial building consisting of 35 – 45 ft. tall panels supported on reinforced concrete piers and framed at roof level by steel joists experienced a collapse failure during the erection process of the tilt-up panels. Two of the panels collapsed crushing the control unit of the lifting crane during the preparation for the erection of an adjacent panel. CA performed, among other tasks, a detailed condition survey of the collapsed panels and the bracing elements including anchors and embeds, and core sampling of the concrete piers and structural slab. CA also performed a forensic structural analysis of the in-place panels, piers, and slab with respect to the support and bracing conditions. CA determined the cause of the failure, developed recommendations for remediation, and provided quality control procedures to complete the remainder of the project.

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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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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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Concrete Rehabilitation with Fiber-Reinforced Composites at an Air Force Base

Kelly Air Force Base (KAFB), the oldest military airfield in the United States, is the home of the Air Logistics Center and the Air Force Electronic Security Command in San Antonio, Texas. The building housing the Air Force Electronic Security Command exhibited distress in the concrete flat slab which resulted in concerns regarding its performance and adequacy for its intended use. CA performed a building condition assessment, identified the cause of distress, and replicated the in-place conditions in a finite element model of the building. The results from the structural analysis were further used to locate the problem areas in the building and they were confirmed by comparing the model predicted distress to the observed distress in the structure. CA designed a fiber reinforced composite repair system for the rehabilitation of the concrete structure.

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Structural Evaluation and Testing of a Parking Structure

Work performed on a parking structure located in Plano, Texas, encompassed a two phase investigation. Phase I consisted of investigating the cause of cracking occurring in the precast, prestressed double tee beams which resulted in the repair or replacement of several double tees. The forensic structural engineering investigation included a condition assessment of the parking garage structure, evaluation of the double tees removed from the structure, sampling of the concrete, non-destructive testing, petrographic examination, and analytical testing. Phase II consisted of investigating the cause of distress in the architectural precast concrete elements by performing a condition assessment and evaluation of the architectural precast elements in-place. It involved determining the adequacy of the erection details, connections, and the overall structural integrity of the precast architectural members.  CA’s forensic consulting work on this project involved performing a structural analysis, sampling, testing, and petrographic examination of the concrete, the review of concrete production and construction practices, and the development of recommendations for rehabilitation and maintenance of the parking garage structure.