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Causes and Ramifications of Distress in Post-Tensioned Multimodal Transit Facility

Carrasquillo Associates (CA) was retained in 2016 to investigate distress in a multimodal transportation hub located in the northeast United States.  The cast-in-place structure consisted of a slab on ground and two elevated slabs supported by a concrete frame. The elevated slabs as well as the concrete beams and girders were post-tensioned (PT). CA investigated concerns related to cracking in the concrete slab and frame, reinforcement cover, and concrete durability. As part of the investigation, CA made a site visit to the structure and also reviewed numerous documents including, among others, design drawings, specifications, photographs, shop drawings, expert reports, testing reports, and communications between parties. CA’s investigation helped to identify the causes and ramifications of the observed distress which allowed the parties to come to an agreement regarding the damages.

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Crane Rail Wear and Misalignment

Carrasquillo Associates (CA) was retained in 2014 to investigate unusual wear on crane rails in a steel processing plant in Pennsylvania. CA conducted an on-site investigation to measure the severity of the crane rail wear and to determine its cause. Custom crane rail measuring devices were fabricated at a machine shop in Austin, TX for this purpose. In addition, CA reviewed numerous surveying reports to verify dimensional compliance between laser surveys, project specifications and industry standards. Life cycle estimates of the crane rails were made based on the information collected during the site visit and research conducted by the US DOT.

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Bridge Construction Investigation and Structure Analysis

The project consisted of an approximately 222 ft. long bridge with concrete piers comprised of two spans supported by eight (8) girders in Colorado.  CA was retained to determine the cause(s) of the failure of several hanger brackets installed to support the overhang formwork supporting the reinforced concrete deck.  The failure occurred during placement of the concrete deck and was isolated to a series of three (3) hangers.  CA’s investigation included review of construction related documents, photos, expert reports, deposition testimony, and relevant industry standards and literature.  In addition, CA performed a structural analysis of the assembly overhang formwork as designed and a finite element analysis of the hanger assembly to determine the effects of installation and fabrication variations.  CA determined the effects of variation in installation and fabrication on the ultimate capacity of the hangers and provided the client with a description of the failure mechanism.

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Alkali-Silica Reaction (ASR) in Pier Structure

Carrasquillo Associates (CA) was retained in 2012 to investigate concerns about the structural integrity and long term performance of a pier structure in Honduras and to determine the deterioration mechanisms affecting the durability, the structural safety and useful life of the structure. The investigation into the structure included visual inspection, crack monitoring, concrete sampling, petrographic examination, chloride testing, structural analysis, and half-cell testing among other items. Based on the testing performed, the internal concrete expansion damage mechanism was identified and the remaining service life of the structural performance of the structure was assessed. Further, several alternatives for restoring the service life and the facility were evaluated. This allowed the client to better understand the cause of the distress that was being observed and what needed to be done to allow the structure to continue to operate safely moving forward.

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Structural Analysis & Investigation of Retaining Wall Failure in Houston

CA was retained to investigate the failure of a retaining wall at a refinery in Houston, Texas, assess the original design and structural adequacy of the wall for its intended purpose, and to determine the cause(s) of the failure. CA’s investigation consisted of reviewing and evaluating construction related documents, including plans and drawings, contract documents, review of legal documents and correspondence, review of expert reports submitted by all parties, review of structural plans and a structural analysis of the structure.

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Concrete Materials Consulting & Structural Analysis for Christopher Columbus Statue in Puerto Rico

Located atop a hillside on the northern shores in the city of Arecibo, Puerto Rico, a Christopher Columbus Statue is being erected and is projected to be completed by late summer of 2015. The Statue consists of over 2,000 exterior pieces of copper and bronze connected to an interior structural steel frame for a total weight of over 600 tons. The structure was originaly designed by Russian sculptor Zurab Tsereteli in 1991 to commemorate the 500th anniversary of Columbus’ 1492 arrival to the Western Hemisphere. CESG’s contribution to the project included consulting services in regards to the mat concrete foundation consisting of the structural design, project specifications’ development, material condition assessments, and construction management. In addition, CESG’s project involvement also included the development of the concrete mixture proportions, concrete placement sequencing, quality control, temperature and maturity monitoring, and implementation of early age protection to the mass concrete elements. Over 1,500 cubic yards of concrete were placed in approximately 8 hours of which all concrete loads were accepted, there was no evidence of cracking with in the mat foundation mass concrete elements, and all the concrete compression strength tests exceeding the 28-day specified design strength in 7 days.

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Tennis Court Complex Forensic Engineering Investigation

CA was retained to perform a structural investigation and determine the cause(s) of the distress in two tennis court facilities located at a junior high school and high school in South Texas. To accommodate construction on expansive soil conditions, the structural system of the tennis courts was comprised of precast concrete hollow core planks (HCP) with a 3 inch concrete topping slab supported by cast-in-place reinforced concrete piers. Shortly after construction the owner noticed distress in the form of cracking and spalling along joints in the playing surface of the tennis courts. It was determined that the cracking was reflective cracking propagating from the longitudinal and transverse joints between HCPs which also resulted in localized spalling of the topping slab. CA’s investigation into the problem consisted of, among others, review and evaluation of construction related documents, review of third party repair options, review of expert reports, review of plans and drawings, detailed condition survey and elevation surveys, exploratory coring to assess the details of the jointing between HPCs, structural analysis of the tennis court system, design of a repair alternative, as well as several site visits to the structures. Through the forensic engineering investigation, CA was able to determine the cause(s) of the distress and provide the client appropriate remediation procedures.

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Foundation Crack Repair of High School in Texas

CA was retained to determine if the alleged movement of the reinforced concrete slab-on-grade foundation at a high school was the result of construction related activities and to develop recommendations for restoring the facility. Shortly after the school’s completion, the owner reported deficiencies including, but not limited to, movement of the slab-on-grade foundation which caused distress consisting of cracking and/or separation of drywall panels, out-of-plumb doorways, and out of level floors. CA’s investigation included the review and evaluation of construction related documents, multiple site visits including a detailed condition survey and relative elevation surveys of the school. Through the investigation, CA was able to determine the cause(s) of movement and develop a mitigation procedure to minimize any future movement and restore functionality of the facility.

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Mud Slab Movement at a Cold Storage Distribution Facility

CA was retained to determine the cause(s) of the movement of a mud slab at a refrigerated warehouse facility in Dallas, TX. The mud slab was a constructed as a 3 in. concrete slab-on-ground to house the refrigeration lines of the warehouse. Prior to placement of the 9 in. thick reinforced concrete slab-on-grade above the mud slab, vertical movement of the mud slab was observed. CA was retained by the General Contractor to determine the cause(s) of the movement and provide recommendations in order to allow construction to continue. The forensic investigation, which included communications with the client, site visits to the facility, a condition survey, soil borings, slab elevation surveys at various points in time, and review of geotechnical reports and construction documents, allowed CA to determine the cause(s) of the distress and allow for construction to continue without having to remove and replace the mud slab.

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Structural Evaluation and Repair of a Precast Parking Garage

CA’s consulting engineering services were retained by a central Texas contractor to assess the structural damage to two double-tee precast concrete beams in a parking garage caused during the renovation of a maintenance room. As part of a renovation project, cast-in-place concrete machine pads were being removed using handheld chipping hammers when a penetration was made through the flanges of two adjacent double-tee beams. CA’s investigation included a site condition survey, measurements, photographic documentation, and a structural analysis of the as-built system to determine the extent of any reduction in the structural performance, safety, and load carrying capacity of the damaged structure. CA was able to provide the contractor with a repair procedure that was implemented concurrently during other operations, thus not delaying the overall renovation project.