Download - Nelson Forensics - AHS Stadium 6-19-14
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ALLEN EAGLE STADIUM Presentation of Findings
Ryan Chancey, Ph.D., P.E.
PRIVILEGED CONFIDENTIAL
INTERIM REVIEW DOCUMENT THIS DOCUMENT IS RELEASED FOR THE PURPOSES OF INTERIM REVIEW UNDER THE AUTHORITY OF RYAN T. CHANCEY, PH.D., P.E.;
TEXAS LICENSE NO. 107198 ON JUNE 16, 2014.
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Presentation Outline Purpose of Investigation
Scope of Investigation
Background
Reinforced Concrete Basics
Strength and Durability Discussion
Nelson Forensics’ Analysis Approach
Findings
Strength Deficiencies
Durability Deficiency
Remediation Discussion
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Purpose of Investigation
Assignment #1; August 2013: Determine the extent and cause of the concrete cracking at the concourse level of the stadium. Assignment #2; February 2014: Evaluate the concourse level of the stadium for structural deficiencies resulting from improper structural design and/or construction. Assignment #3; March 2014: Evaluate the entire stadium facility for structural deficiencies resulting from improper structural design and/or construction. Assignment #4; April 2014: Partner with Datum Engineering for design development of a repair and strengthening plan to rectify identified structural deficiencies.
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Scope of Investigation
1. Performed on-site observations of distress and as-built conditions
Documented observed conditions and distress
Cracks Emphasized by Author
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Scope of Investigation
1. Performed on-site observations of distress and as-built conditions
Photographically and graphically documented observed conditions and distress
Developed a distress map of the cracking at the concourse
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NORTH
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Scope of Investigation
2. Coordinated a limited concrete materials testing regime for the concourse level
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Scope of Investigation 3. Reviewed construction documents; including plans,
specifications, shop drawings, design bulletins, and change orders
4. Developed 2- and 3-dimensional analytical models of the stadium structure; performed structural analysis
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Scope of Investigation
5. Identified structurally deficient systems and components
6. Commenced design of repair and strengthening,
in concert with Datum Engineering (ongoing)
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Strength vs. Durability
Strength: The ability of a structural member or system to
support its own weight and superimposed loads with a code-specified factor of safety
Durability: The ability of a structural member or system to serve
its intended purpose for its required service life
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A bit about concrete… 1 of 2
Concrete is much stronger when you push on it than when you pull or bend it… Thus, reinforcing steel is added to compensate
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A bit about concrete… 2 of 2
Concrete Shrinks!
Cracks Emphasized by Author
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Remember:
1. Concrete needs properly designed steel reinforcement for strength and durability.
2. Concrete without properly designed reinforcement and/or joints will make its own joints by cracking.
Also: Reinforcing steel corrodes (rusts) when cracks in
concrete allow exposure to air and water…
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Structural Systems Analyzed
Concrete Piers Concrete Retaining Walls Concrete Concourse Framing Concrete Columns Concrete Seating Steel Press Box
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Structural Systems Analyzed
Low Steel Buildings Scoreboards
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Summary of Findings
Structurally Deficient: Retaining walls Concourse framing Press box support columns Press box structure Single-story structures South scoreboard Durability (life cycle)
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Strength Deficiencies
Strength: The ability of a structural member or
system to support its own weight and superimposed loads with a code-specified factor of safety
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Retaining Walls
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Concourse Framing
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Concourse Framing
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Press Box Support Columns
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Press Box Support Columns
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Press Box Structure
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Press Box Structure
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Low Steel Buildings and South Scoreboard
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Durability Deficiency
Durability: The ability of a structural member or
system to serve its intended purpose for its required service life.
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Durability
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Durability
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Durability
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Durability
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Summary of Findings
Structurally Deficient: Retaining walls Concourse framing Press box support columns Press box structure Single-story structures South scoreboard Durability (life cycle)
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Remediation Approaches
Design-Bid-Build Key Advantage: Total cost for repair known prior to commencement of construction
Key Disadvantage: Construction can not begin until all engineering design is complete (≈5 months) Staged Design/Construction Key Advantage: Design is segmented into “packages” such that construction begins as packages are issued
Key Disadvantage: Total cost of construction uncertain until later in the repair process
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Staged Design Schedule
6/1/14 10/1/14 9/1/14 8/1/14 7/1/14 11/1/14
May 1 2015
Concourse Radar Scan
Concourse Fiber Wrap
Concourse Durability
Press Box
Concourse Heavy Structural
Retaining Walls
Low Steel Buildings
CONSTRUCTION
Assumes Contractor Retained by July 2014
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