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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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Page 1: Nelson Forensics - AHS Stadium 6-19-14

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.

Page 2: Nelson Forensics - AHS Stadium 6-19-14

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

Page 3: Nelson Forensics - AHS Stadium 6-19-14

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.

Page 4: Nelson Forensics - AHS Stadium 6-19-14

Scope of Investigation

1. Performed on-site observations of distress and as-built conditions

Documented observed conditions and distress

Cracks Emphasized by Author

Page 5: Nelson Forensics - AHS Stadium 6-19-14

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

Page 6: Nelson Forensics - AHS Stadium 6-19-14

NORTH

Page 7: Nelson Forensics - AHS Stadium 6-19-14

Scope of Investigation

2. Coordinated a limited concrete materials testing regime for the concourse level

Page 8: Nelson Forensics - AHS Stadium 6-19-14

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

Page 9: Nelson Forensics - AHS Stadium 6-19-14

Scope of Investigation

5. Identified structurally deficient systems and components

6. Commenced design of repair and strengthening,

in concert with Datum Engineering (ongoing)

Page 10: Nelson Forensics - AHS Stadium 6-19-14

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

Page 11: Nelson Forensics - AHS Stadium 6-19-14

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

Page 12: Nelson Forensics - AHS Stadium 6-19-14

A bit about concrete… 2 of 2

Concrete Shrinks!

Cracks Emphasized by Author

Page 13: Nelson Forensics - AHS Stadium 6-19-14

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…

Page 14: Nelson Forensics - AHS Stadium 6-19-14

Structural Systems Analyzed

Concrete Piers Concrete Retaining Walls Concrete Concourse Framing Concrete Columns Concrete Seating Steel Press Box

Page 15: Nelson Forensics - AHS Stadium 6-19-14

Structural Systems Analyzed

Low Steel Buildings Scoreboards

Page 16: Nelson Forensics - AHS Stadium 6-19-14

Summary of Findings

Structurally Deficient: Retaining walls Concourse framing Press box support columns Press box structure Single-story structures South scoreboard Durability (life cycle)

Page 17: Nelson Forensics - AHS Stadium 6-19-14

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

Page 18: Nelson Forensics - AHS Stadium 6-19-14

Retaining Walls

Page 19: Nelson Forensics - AHS Stadium 6-19-14

Concourse Framing

Page 20: Nelson Forensics - AHS Stadium 6-19-14

Concourse Framing

Page 21: Nelson Forensics - AHS Stadium 6-19-14

Press Box Support Columns

Page 22: Nelson Forensics - AHS Stadium 6-19-14

Press Box Support Columns

Page 23: Nelson Forensics - AHS Stadium 6-19-14

Press Box Structure

Page 24: Nelson Forensics - AHS Stadium 6-19-14

Press Box Structure

Page 25: Nelson Forensics - AHS Stadium 6-19-14

Low Steel Buildings and South Scoreboard

Page 26: Nelson Forensics - AHS Stadium 6-19-14

Durability Deficiency

Durability: The ability of a structural member or

system to serve its intended purpose for its required service life.

Page 27: Nelson Forensics - AHS Stadium 6-19-14

Durability

Page 28: Nelson Forensics - AHS Stadium 6-19-14

Durability

Page 29: Nelson Forensics - AHS Stadium 6-19-14

Durability

Page 30: Nelson Forensics - AHS Stadium 6-19-14

Durability

Page 31: Nelson Forensics - AHS Stadium 6-19-14

Summary of Findings

Structurally Deficient: Retaining walls Concourse framing Press box support columns Press box structure Single-story structures South scoreboard Durability (life cycle)

Page 32: Nelson Forensics - AHS Stadium 6-19-14

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

Page 33: Nelson Forensics - AHS Stadium 6-19-14

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

Page 34: Nelson Forensics - AHS Stadium 6-19-14

Discussion


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