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Structural Engineering Consulting: Expressway Concrete Bridge

The project involved converting a section of a concrete pavement highway in Puerto Rico with two lanes of traffic in each direction into an expressway concrete bridge requiring three lanes in each direction. CA’s structural engineering consulting services included evaluating the structural adequacy of the as-built cast-in-place concrete bridge foundations to resist the design loading conditions. CA performed a detailed structural analysis of the bridge foundations using both traditional beam theory and strut-and-tie modeling.  CA conducted an investigation that included, among other things, a review and interpretation of specifications, plans and construction drawings, concrete cylinder and core strength test reports, and applicable industry standards. Further, CA developed recommendations to improve the durability of the concrete foundation and to ensure the service life of the bridge structure in service.

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Moisture Induced Corrosion of Precast Double-Tee Roof

CA performed an initial investigation to determine the cause(s) of the observed distress in a roof of a parking garage structure consisting of precast double-tee girders in a hotel located in Laredo, Texas. CA performed an initial condition assessment and developed recommendations for a comprehensive investigation to determine a remediation procedure for the observed distress, which was indicative of distress caused by moisture intrusion. CA’s recommendations for a comprehensive investigation included determining the cause of the moisture intrusion, performing repairs to eliminate additional moisture intrusion, and assessing the extent of damage affecting the integrity of structural members with rebar corrosion and loss of concrete section.

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Apartment Complex Parking Lot Pavement Assessment

CA was retained to investigate the cause(s) of the distress observed in the concrete pavement parking lots at a complex in Murphy, Texas. The complex was comprised of four buildings and each had one or two concrete pavement parking lots surrounding it that were connected with inner drives throughout the complex. The parking lots consisted of both heavy and regular duty pavements. CA’s site visits consisted of performing a detailed survey of the cracked areas in the pavement including photo documentation, collection of concrete cores and soil samples, and observation of the demolition of selected areas of pavement. The results from the forensic examination of the concrete cores, soil samples, and construction records provided the necessary data for CA’s expert opinions regarding concrete repair methods for the pavement areas.

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Condition Assessment and Repair Recommendations for a Residential Building

A 14 story residential building constructed in the 1970s consisted of a cast-in-place concrete beam and slab framing system with CMU walls and a brick façade. CA’s investigation focused on evaluating the condition and structural adequacy of several of the building’s elements, including the concrete walkways, stairwells, and precast panels attached to the building’s balconies and stairwells. CA performed, among other things, a detailed condition survey and visual examination of the various structural elements, a review of the drawings and plans, and an evaluation of the materials utilized in previous repairs. CA provided the client with concrete repair recommendations, including, but not limited to repair methods, guidelines, and selection of the appropriate repair materials.

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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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Regional Health Science Center Cracked Concrete Repair

The Regional Academic Health Center is an extension of University of Texas at San Antonio Medical School located in Harlingen, Texas. During the construction of the first floor cast-in-place reinforced concrete elevated slab, significant cracking of the structural members occurred. CA was retained to investigate the cracked floor system and to determine whether remedial action was necessary. CA’s investigation consisted of a condition assessment and structural analysis of the floor system. CA determined the cracks to be cosmetic in nature and not structural. CA developed a concrete crack repair remediation plan consisting of sealing the cracks using a high molecular weight methacrylate. CA was responsible for supervising the concrete restoration services and verifying the performance of the repair.

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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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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.