Forensic Analysis of an Elevated Pool Vault

Brian Eubanks; Garrett Ryan; Derek Patoskie

doi:10.51501/jotnafe.v42i1.945

Authors

Brian Eubanks Paragon Structural Engineering https://orcid.org/0009-0009-4755-9032
Garrett Ryan NAFE Member https://orcid.org/0009-0009-4755-9032
Derek Patoskie PSE Global https://orcid.org/0009-0009-6560-1388

DOI:

https://doi.org/10.51501/jotnafe.v42i1.945

Keywords:

Analysis, alkali-silica, ASR, Building code, construction, case study, craze cracks, defect, deficiency, demolition, forensic engineering, evaluation, finite element, ground-penetrating radar, GPR, gunite, Portland cement, investigation, map cracks, methodology, non-prestressed reinforcement, performancepetrography, performance, petrography, plaster, podium slab, pool, reaction, shear key, shotcrete, siliceous aggregates, slab, specification, variances, vault

Abstract

Distress observed in the plaster lining and gunite/shotcrete of a pool structure located within a podium slab on the third floor of an eight-story student housing building located in central Texas was determined to be causally related to the gunite/shotcrete mix. The gunite/shotcrete mix combined high alkali Portland cement with siliceous aggregates sufficient to generate alkali-silica reaction (ASR). Additional construction deficiencies associated with the thickness of the pool shell and the clear cover over the steel reinforcement were determined to have exacerbated the distress in the structure. Upon demolition of the pool structure, design deficiencies were subsequently identified in the recessed concrete vault that supported the pool structure. The identified design deficiencies included inaccurate structural design and analysis with finite element modeling software, inconsistencies in the thickness of the floor slab, omission of a shear key at the abutment/connection of the floor slab and the vault walls, and an inadequate amount of bonded, non-prestressed reinforcement in the floor slab. These deficiencies culminated in the demolition and reconstruction of the vault. This paper will explore the different parties involved in the design and construction of the project, the errors that resulted in deficient conditions, and the positions maintained by the different forensic engineering consultants representing the various parties.

Author Biographies

Garrett Ryan, NAFE Member

Garrett T. Ryan, PE, DFE is an Associate Principal Structural Engineer for Paragon Structural Engineering, LTD. (PSE), a structural design and forensic investigation firm based in Plano, Texas. Mr. Ryan holds a B.S. degree in Architectural (Structural) Engineering from the University of Texas in Austin. Mr. Ryan is a Licensed Professional Engineer in 7 states, is a Board-Certified Diplomate in Forensic Engineering by the National Academy of Forensic Engineers, is Building Envelope Trained and Certified by the Building Envelope Science Institute, is a Certified Windstorm Inspector by the Texas Department of Insurance and is also a Model Law Engineer with the National Council of Examiners for Engineering and Surveying (NCEES). Mr. Ryan currently has over 16 years of experience leading technical staff in the structural design and forensic investigation of planned and existing structures. Mr. Ryan’s forensic expertise includes building envelopes, soil-structure interactions, performance of structural systems, and determination of cause origin, and extent of peril damage. Mr. Ryan has performed thousands of forensic investigations, and he has authored hundreds of expert reports for use in mediation, arbitration, and/or litigation. Mr. Ryan has performed dozens of presentations and private training sessions to educate builders with regard to construction and performance of building envelopes.

Derek Patoskie, PSE Global

Derek T. Patoskie, MECE, PE, is a Staff Structural Engineer for Paragon Structural Engineering, LTD. (PSE), a structural design and forensic investigation firm based in Plano, Texas. Mr. Patoskie holds both B.S. and M.E. degrees in Civil Engineering from Texas A&M University. Mr. Patoskie is a Licensed Professional Engineer in 2 states, is Building Envelope Trained and Certified by the Building Envelope Science Institute, Exterior Design Institute, and is also a Model Law Engineer with the National Council of Examiners for Engineering and Surveying (NCEES). Mr. Patoskie currently has over 3 years of experience leading technical staff in the structural design and forensic investigation of planned and existing structures. Mr. Patoskie’s forensic expertise includes building envelopes, soil-structure interactions, performance of structural systems, and determination of cause origin, and extent of peril damage. Mr. Patoskie has performed hundreds of forensic investigations, and he has authored dozens of expert reports for use in mediation, arbitration, and/or litigation.

References

ACI Committee 201, 2008, “Guide for Conducting a Visual Inspection of Concrete in Service,” American Concrete Institute, Farmington Hills, MI, 2008.

N. S. Admad and R. Hamid, "Relationship between Moisture Content and Dielectric Values of Concrete using Ground Penetrating Radar Method," Journal of Advanced Research Design, vol. 57, no. 1, pp. 21-33, 2019.

American Shotcrete Association, Compressive (Strength) Values of Pool Shotcrete [Online]. Available: https://shotcrete.org/wp-content/uploads/2020/01/ASAPositionPaper_PoolRec_1.pdf.

ASTM Standard C856-04, 2004, “Standard Practice for Petrographic Examination of Hardened Concrete,” ASTM International, West Conshohocken, PA, 2004, DOI: 10.1520/C0856-04.

E. Giannini, K. Folliard, J. Zhu, O. Bayrak, K. Kreitman, Z. Webb, and B. Hanson, “Non-Destructive Evaluation of In-Service Concrete Structures Affected by Alkali-Silica Reaction (ASR) or Delayed Ettringite Formation (DEF) – Final Report, Part 1”, Center for Transportation Research, The University of Texas at Austin, Austin, TX, Texas A&M Transportation Institute, College Station, TX, FHWA/TX-13/0-6491-1, 2013.

Michael, D.A. Thomas, Kevin J. Folliard, Benoit Fournier, Patrice Rivard, and Thano Drimalas, “Methods for Evaluating and Treating ASR-Affected Structures: Results of Field Application and Demonstration Projects – Volume I: Summary of Findings and Recommendations,” The Transtec Group, Austin, TX, FHWA-HIF-14-0002, 2013.

Bentley Systems, Inc., Exton, PA, USA, 2024. RAM Concept. Available: https://bentley.com/software/ram-concept/

ACI Committee 318, 2011, “Building Code Requirements for Structural Concrete (ACI 318-11) and Commentary,” American Concrete Institute, Farmington Hills, MI, 2011.

B. Eubanks, D. Patoskie, and G. Ryan, “Beyond the Building Code: A Forensic Approach to Construction Defect Evaluation Utilizing the Construction Variance Evaluation Methodology,” JotNAFE, vol. 41, no. 2, Jan. 2025.