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ASCE Structural Engineering ConferenceIowa State University CenterAmes, Iowa
November 4, 2013
ASCE Structural Engineering ConferenceIowa State University CenterAmes, Iowa
November 4, 2013
Structural Forensic EngineeringCase StudiesStructural Forensic EngineeringCase Studies
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• Introduction
• Background
• Two common pitfalls
• Case studies:
• Miami Dade garage collapse
• NYC Gap Analysis
• Questions, discussion
• Introduction
• Background
• Two common pitfalls
• Case studies:
• Miami Dade garage collapse
• NYC Gap Analysis
• Questions, discussion
Agenda
![Page 3: Structural Forensic Engineering Case · PDF fileStructural Forensic Engineering Case Studies • Introduction ... Formwork failures due to wind Leading edge formwork failure: • Reported](https://reader033.vdocuments.site/reader033/viewer/2022042708/5a78af007f8b9ae6228b6e84/html5/thumbnails/3.jpg)
• Educated at Iowa State University
• 23-year career in structural design, management
• Single family residences to 50 story buildings
• Constructed value nearly $2 billion
• 17-year career in structural forensics
• Investigated a variety of structures
• Constructed with a variety of materials
• Member of ASCE, SEAOI, AISC, ACI, ABA
• Educated at Iowa State University
• 23-year career in structural design, management
• Single family residences to 50 story buildings
• Constructed value nearly $2 billion
• 17-year career in structural forensics
• Investigated a variety of structures
• Constructed with a variety of materials
• Member of ASCE, SEAOI, AISC, ACI, ABA
Introduction: Jeffrey Garrett, Ph.D., S.E.
![Page 4: Structural Forensic Engineering Case · PDF fileStructural Forensic Engineering Case Studies • Introduction ... Formwork failures due to wind Leading edge formwork failure: • Reported](https://reader033.vdocuments.site/reader033/viewer/2022042708/5a78af007f8b9ae6228b6e84/html5/thumbnails/4.jpg)
• Introduction
• Background
• Two common pitfalls
• Case studies
• Miami Dade garage collapse
• NYC Gap Analysis
• Questions, discussion
• Introduction
• Background
• Two common pitfalls
• Case studies
• Miami Dade garage collapse
• NYC Gap Analysis
• Questions, discussion
Agenda
![Page 5: Structural Forensic Engineering Case · PDF fileStructural Forensic Engineering Case Studies • Introduction ... Formwork failures due to wind Leading edge formwork failure: • Reported](https://reader033.vdocuments.site/reader033/viewer/2022042708/5a78af007f8b9ae6228b6e84/html5/thumbnails/5.jpg)
Forensic engineering
• Name given to the activity of failure investigation
• Implies presentation of findings in litigation
Forensic engineering in construction
• Most cases involve lazy mistakes
• 90% of cases typically settle prior to litigation
• Process is still costly in terms of time & dollars
Forensic engineering
• Name given to the activity of failure investigation
• Implies presentation of findings in litigation
Forensic engineering in construction
• Most cases involve lazy mistakes
• 90% of cases typically settle prior to litigation
• Process is still costly in terms of time & dollars
Structural forensic engineering
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Failure
• Condition of not meeting an intended objective
Examples of failure• Serviceability
• Excessive deflection and/or vibrations
• Durability
• Structural distress
• Partial or total collapse
Failure
• Condition of not meeting an intended objective
Examples of failure• Serviceability
• Excessive deflection and/or vibrations
• Durability
• Structural distress
• Partial or total collapse
Failure defined
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• Fundamental conceptual errors
• Design errors, omissions
• Fabrication, manufacturing defects
• Construction defects
• Materials defects
• Operational errors
• Fundamental conceptual errors
• Design errors, omissions
• Fabrication, manufacturing defects
• Construction defects
• Materials defects
• Operational errors
Sources of failure
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Sources of construction litigation
Source: US Government Services Administration
19.00%13.20%
10.10%9.70%
8.90%8.00%
6.70%5.40%
4.80%3.60%
2.60%2.60%
1.60%0.90%0.80%0.80%0.70%
0.30%0.30%
0.00% 2.50% 5.00% 7.50% 10.00% 12.50% 15.00% 17.50% 20.00%
Modifications/change ordersContract disputes
Delay claimsPayment disputes
Incomplete specificationsUnforeseen site conditions
Termination for defaultDeficient work
Liquidated damagesConstruction site safety
Errors & omissionsFacility performance
OverheadPricing/budget overruns
Bidding proceduresOwner furnished equipment
Architect/engineerSubcontractor disputes
Value engineering
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Litigation is big business
American Bar Association estimates that:
• Consulting structural engineering firms
• Almost 50% named in a suit
• Structural engineers
• 1 in 10 will be personally named
American Bar Association estimates that:
• Consulting structural engineering firms
• Almost 50% named in a suit
• Structural engineers
• 1 in 10 will be personally named
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Estimates by American Society of Civil Engineers:
• Annual claims against member companies
• Exceeds $5 billion annually
• This figure is based on insurance estimates
• Underestimates actual amounts
• Most settlements never made public
Estimates by American Society of Civil Engineers:
• Annual claims against member companies
• Exceeds $5 billion annually
• This figure is based on insurance estimates
• Underestimates actual amounts
• Most settlements never made public
Litigation is big business
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• Total costs to defend a claim include:
• Non-billable time, lost revenue
• Legal fees, expert fees
• PLUS the amount of any claim settlement
• Immeasurable consequences include:
• Damaged reputation
• Ability to market
• Impact to future business
• Total costs to defend a claim include:
• Non-billable time, lost revenue
• Legal fees, expert fees
• PLUS the amount of any claim settlement
• Immeasurable consequences include:
• Damaged reputation
• Ability to market
• Impact to future business
Litigation is big business
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• Introduction
• Background
• Risk management: two common pitfalls
• Case studies:
• Miami Dade garage collapse
• NYC Gap Analysis
• Questions, discussion
• Introduction
• Background
• Risk management: two common pitfalls
• Case studies:
• Miami Dade garage collapse
• NYC Gap Analysis
• Questions, discussion
Agenda
![Page 13: Structural Forensic Engineering Case · PDF fileStructural Forensic Engineering Case Studies • Introduction ... Formwork failures due to wind Leading edge formwork failure: • Reported](https://reader033.vdocuments.site/reader033/viewer/2022042708/5a78af007f8b9ae6228b6e84/html5/thumbnails/13.jpg)
Two key areas that need improvement:
• Contractual language
• The engineer had signed a bad contract
• Engineers make for bad negotiators
• Maintain good records
• Keep your house in order
Two key areas that need improvement:
• Contractual language
• The engineer had signed a bad contract
• Engineers make for bad negotiators
• Maintain good records
• Keep your house in order
Risk management
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Contract clauses that receive the most attention:
• Scope of Work
• Standard of Care
• Limitation of Liability
• Indemnification
These are the clauses your clients will attempt to modify to their benefit
Contract clauses that receive the most attention:
• Scope of Work
• Standard of Care
• Limitation of Liability
• Indemnification
These are the clauses your clients will attempt to modify to their benefit
Contractual issues
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Contract clauses that receive the most attention:
• Scope of Work
• Establishes legal obligations
• This is the work to be performed
• Sets the standard of care for services rendered
• Insist that the scope be sufficiently detailed
• First document to be reviewed in a suit
Contract clauses that receive the most attention:
• Scope of Work
• Establishes legal obligations
• This is the work to be performed
• Sets the standard of care for services rendered
• Insist that the scope be sufficiently detailed
• First document to be reviewed in a suit
Contractual issues
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Contract clauses that receive the most attention:
• Standard of Care
• “The work will be performed to the highest standard……”
• Sets an unnecessary high standard
• Higher than what is normally expected
• Sets the bar on how you will be judged
Contract clauses that receive the most attention:
• Standard of Care
• “The work will be performed to the highest standard……”
• Sets an unnecessary high standard
• Higher than what is normally expected
• Sets the bar on how you will be judged
Contractual issues
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Contract clauses that receive the most attention:
• Limitation of Liability
• Endeavor to limit your liability to the value of the fee or some dollar value
• Include language that limits your liability to only those actions you have control over
• However, you cannot limit your liability if litigation was caused by your negligence
Contract clauses that receive the most attention:
• Limitation of Liability
• Endeavor to limit your liability to the value of the fee or some dollar value
• Include language that limits your liability to only those actions you have control over
• However, you cannot limit your liability if litigation was caused by your negligence
Contractual issues
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Contract clauses that receive the most attention:
• Indemnification
• Include language that indemnifies you from third party law suits
• You have no control over their actions
• Include language that requires client to defend you in the event of a third party law suit
Contract clauses that receive the most attention:
• Indemnification
• Include language that indemnifies you from third party law suits
• You have no control over their actions
• Include language that requires client to defend you in the event of a third party law suit
Contractual issues
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Activities that should be business as usual:
• Files to be maintained indefinitely include:
• Proposals
• Contract negotiation notes
• Scope of work
• Schedule
• Draft contracts
• Executed contracts
Activities that should be business as usual:
• Files to be maintained indefinitely include:
• Proposals
• Contract negotiation notes
• Scope of work
• Schedule
• Draft contracts
• Executed contracts
Maintain good records
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Activities that should be business as usual:
• Recommend you maintain project files:
• The sum of:
• Time set by Statue of Limitation
Plus
• Time set by Statue of Repose
Activities that should be business as usual:
• Recommend you maintain project files:
• The sum of:
• Time set by Statue of Limitation
Plus
• Time set by Statue of Repose
Maintain good records
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Activities that should be business as usual:
• Statute of Limitation:
• Bars action after a fixed period of time• Regardless of whether damage or injury has
been discovered during that period
• Statute of Repose:
• Bars causes of action after a fixed period of time following discovery of an error
Activities that should be business as usual:
• Statute of Limitation:
• Bars action after a fixed period of time• Regardless of whether damage or injury has
been discovered during that period
• Statute of Repose:
• Bars causes of action after a fixed period of time following discovery of an error
Maintain good records
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Activities that should be business as usual:
• Maintain the calculation file
• Will calc’s make sense to a stranger in 10 years?
• Keep only calc’s that define completed project
• Follow office policy and procedure:
• Sequentially number, check and initial each sheet
Activities that should be business as usual:
• Maintain the calculation file
• Will calc’s make sense to a stranger in 10 years?
• Keep only calc’s that define completed project
• Follow office policy and procedure:
• Sequentially number, check and initial each sheet
Maintain good records
![Page 23: Structural Forensic Engineering Case · PDF fileStructural Forensic Engineering Case Studies • Introduction ... Formwork failures due to wind Leading edge formwork failure: • Reported](https://reader033.vdocuments.site/reader033/viewer/2022042708/5a78af007f8b9ae6228b6e84/html5/thumbnails/23.jpg)
Activities that should be business as usual:
• Establish a written retention policy and follow it
• No matter how long records are to be retained:
• Follow the retention policy strictly
• Avoids any question of impropriety when a project ends up in litigation
• Produce all documents according to the retention policy
Activities that should be business as usual:
• Establish a written retention policy and follow it
• No matter how long records are to be retained:
• Follow the retention policy strictly
• Avoids any question of impropriety when a project ends up in litigation
• Produce all documents according to the retention policy
Maintain good records
![Page 24: Structural Forensic Engineering Case · PDF fileStructural Forensic Engineering Case Studies • Introduction ... Formwork failures due to wind Leading edge formwork failure: • Reported](https://reader033.vdocuments.site/reader033/viewer/2022042708/5a78af007f8b9ae6228b6e84/html5/thumbnails/24.jpg)
• Introduction
• Background
• Risk management: two common pitfalls
• Case studies
• Miami Dade garage collapse
• NYC Gap Analysis
• Questions, discussion
• Introduction
• Background
• Risk management: two common pitfalls
• Case studies
• Miami Dade garage collapse
• NYC Gap Analysis
• Questions, discussion
Agenda
![Page 25: Structural Forensic Engineering Case · PDF fileStructural Forensic Engineering Case Studies • Introduction ... Formwork failures due to wind Leading edge formwork failure: • Reported](https://reader033.vdocuments.site/reader033/viewer/2022042708/5a78af007f8b9ae6228b6e84/html5/thumbnails/25.jpg)
• I–35W bridge collapse, Minneapolis
• Big Blue crane collapse, Milwaukee
• Tropicana parking garage collapse
• Big Dig roof collapse, Boston
• I–35W bridge collapse, Minneapolis
• Big Blue crane collapse, Milwaukee
• Tropicana parking garage collapse
• Big Dig roof collapse, Boston
Front page projects
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• Structural failure, collapse
• Distress, performance issues
• Design or construction defects
• Materials failures, performance issues
• Standard of care, delays, loss of use & business
• Structural failure, collapse
• Distress, performance issues
• Design or construction defects
• Materials failures, performance issues
• Standard of care, delays, loss of use & business
Most projects don’t even make the news
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• Parking garage under construction
• Precast concrete construction
• Nearly complete with precast erection
• 5 supported levels
• Grade, Level 1
• Roof, Level 6
• Parking garage under construction
• Precast concrete construction
• Nearly complete with precast erection
• 5 supported levels
• Grade, Level 1
• Roof, Level 6
Miami Dade College parking garage collapse
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Miami Dade College parking garage collapse
C1
B4B3
B2B1
A1
B5
A2
C2
A3
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Miami Dade College parking garage collapse
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Miami Dade College parking garage collapse
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Miami Dade College parking garage collapse
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Miami Dade College parking garage collapse
Dead weight applied to Column B3 at collapse:
• Unfactored P = 900 kips
• Unfactored stress in concrete = 1.0 k.s.i.
• Not excessive for f’c = 9,000 p.s.i.
• Attention turned to the crane
• The crane had bumped Column B1
Dead weight applied to Column B3 at collapse:
• Unfactored P = 900 kips
• Unfactored stress in concrete = 1.0 k.s.i.
• Not excessive for f’c = 9,000 p.s.i.
• Attention turned to the crane
• The crane had bumped Column B1
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Miami Dade College parking garage collapse
The “crane accident” theory
• Boom had contacted Column B1
• Incident had occurred 3 days earlier
• Theory: Structure at point of incipient collapse
• Crane had been inspected for damage
• Was returned to service
• Contact left paint marks on Column B1
• No additional damage to column was found
The “crane accident” theory
• Boom had contacted Column B1
• Incident had occurred 3 days earlier
• Theory: Structure at point of incipient collapse
• Crane had been inspected for damage
• Was returned to service
• Contact left paint marks on Column B1
• No additional damage to column was found
![Page 34: Structural Forensic Engineering Case · PDF fileStructural Forensic Engineering Case Studies • Introduction ... Formwork failures due to wind Leading edge formwork failure: • Reported](https://reader033.vdocuments.site/reader033/viewer/2022042708/5a78af007f8b9ae6228b6e84/html5/thumbnails/34.jpg)
Miami Dade College parking garage collapse
Column B3
• Almost 5-feet of column base was missing
• Reinforcing was splayed out
• Specific shape to the failure surface
Column B3
• Almost 5-feet of column base was missing
• Reinforcing was splayed out
• Specific shape to the failure surface
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Miami Dade College parking garage collapse
Column B3
• Specific shape to the failure surface
Column B3
• Specific shape to the failure surface
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Miami Dade College parking garage collapse
Column B3 baseColumn B3 base
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Miami Dade College parking garage collapse
Theory: Failure of Column B3 initiated collapse
• Facts:
• No grout installed
• Column rested on 8-inch square shims
• Stress in column = 1.0 k.s.i.
• Stress transferred to shims = 14.0 k.s.i.
• Exceeds design f’c by 5.0 k.s.i.
• Why didn’t the failure occur sooner?
Theory: Failure of Column B3 initiated collapse
• Facts:
• No grout installed
• Column rested on 8-inch square shims
• Stress in column = 1.0 k.s.i.
• Stress transferred to shims = 14.0 k.s.i.
• Exceeds design f’c by 5.0 k.s.i.
• Why didn’t the failure occur sooner?
![Page 38: Structural Forensic Engineering Case · PDF fileStructural Forensic Engineering Case Studies • Introduction ... Formwork failures due to wind Leading edge formwork failure: • Reported](https://reader033.vdocuments.site/reader033/viewer/2022042708/5a78af007f8b9ae6228b6e84/html5/thumbnails/38.jpg)
Miami Dade College parking garage collapse
• Tested aggregate, cement, concrete:
• Aggregate susceptible to creep
• Found micro-cracking of the concrete
• Took time to form, coalesce
• Failure planes perpendicular to major stress
• Confinement of column base by column ties
• Micro-cracking occurs until failure plane forms
• Bottom 5-feet of Column B3 disappeared
• Tested aggregate, cement, concrete:
• Aggregate susceptible to creep
• Found micro-cracking of the concrete
• Took time to form, coalesce
• Failure planes perpendicular to major stress
• Confinement of column base by column ties
• Micro-cracking occurs until failure plane forms
• Bottom 5-feet of Column B3 disappeared
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Miami Dade College parking garage collapse
B3
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Miami Dade College parking garage collapse
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NYC DOB retained CTLGroup
• Rash of construction accidents
• Prompted action by the Mayor
• Objective:
• Perform a GAP analysis of current practice
• Make recommendations
• Modify code, if needed
NYC DOB retained CTLGroup
• Rash of construction accidents
• Prompted action by the Mayor
• Objective:
• Perform a GAP analysis of current practice
• Make recommendations
• Modify code, if needed
High Rise Concrete Overview
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42
High Rise Concrete Overview
High rise construction observations
• HRCO concrete team:
• Established data base of site conditions
• Total sites visited: 181 site observations
• Quality & formwork data based on:
• Subset of 98 active construction sites
• Each inspected by P.E.
High rise construction observations
• HRCO concrete team:
• Established data base of site conditions
• Total sites visited: 181 site observations
• Quality & formwork data based on:
• Subset of 98 active construction sites
• Each inspected by P.E.
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High rise construction observations
• Site distribution:
• 49 union sites (50%)
• 41 non-union sites (42%)
• 8 unknown affiliation (8%)
High rise construction observations
• Site distribution:
• 49 union sites (50%)
• 41 non-union sites (42%)
• 8 unknown affiliation (8%)
High Rise Concrete Overview
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UnionNon-UnionUnknown
High Rise Concrete Overview
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High-rise Concrete Areas of InterestHigh-rise Concrete Areas of Interest
Formwork Issues General Site Safety
Special Inspection and Construction
Quality
1 3Worker Falls
42
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High-rise Concrete Formwork IssuesHigh-rise Concrete Formwork Issues
High Rise Concrete Overview
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High Rise Concrete Overview
High rise concrete formwork issues
• Observed inadequacies:
• Incomplete design specifications
• Improper installation and sequencing
• Damage due to wind
High rise concrete formwork issues
• Observed inadequacies:
• Incomplete design specifications
• Improper installation and sequencing
• Damage due to wind
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All Projects
Sample Size 98Number of CriticalFormwork Defects 57 (58%)
HRCO Observed Defects
High Rise Concrete Overview
High rise concrete formwork issuesHigh rise concrete formwork issues
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High Rise Concrete Overview
High rise concrete formwork issues
Critical formwork defects:
• No stamped formwork design (per NYC Code)
• Formwork construction not in conformance to design
• Premature stripping or premature reshore removal
• Insufficient number of reshored floors (per design)
• Insufficient number of shored floors (per design)
High rise concrete formwork issues
Critical formwork defects:
• No stamped formwork design (per NYC Code)
• Formwork construction not in conformance to design
• Premature stripping or premature reshore removal
• Insufficient number of reshored floors (per design)
• Insufficient number of shored floors (per design)
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High Rise Concrete Overview
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High Rise Concrete Overview
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High Rise Concrete Overview
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Formwork failures due to wind
Leading edge formwork failure:
• Reported winds of 30-40 mph
• 808 Columbus, Manhattan
• June 11, 2008
Leading edge formwork failure:
• Reported winds of 30-40 mph
• 469 West Street, Manhattan
• March 9, 2008
Formwork failures due to wind
Leading edge formwork failure:
• Reported winds of 30-40 mph
• 808 Columbus, Manhattan
• June 11, 2008
Leading edge formwork failure:
• Reported winds of 30-40 mph
• 469 West Street, Manhattan
• March 9, 2008
High Rise Concrete Overview
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Historic Wind Incidents
Address Boro. Incident Date Description
Jay Street Brooklyn 7/24/2006Wind dislodged several deck panels
from formwork on 27th floor.
Broadway Manhattan7/12/2006 Wind dislodged vertical column
formwork from upper floor
Spring St. Manhattan 12/23/2007Wind Dislodged Shoring Element
from the 39th Floor
11th Ave Manhattan 10/22/08Wind Dislodged (2) 3x4 timber posts
from 16th floor. Leading Edge deck lifted
High Rise Concrete Overview
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High Rise Concrete Overview
Formwork recommendations
1. Require that essential specification be included on stamped formwork designs
• Reshoring sequences and schedules
• Required numbers of reshored floor levels
• Clear information regarding:
• Spacing and layout
• Lumber grade and design strengths
Formwork recommendations
1. Require that essential specification be included on stamped formwork designs
• Reshoring sequences and schedules
• Required numbers of reshored floor levels
• Clear information regarding:
• Spacing and layout
• Lumber grade and design strengths
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High Rise Concrete Overview
Formwork recommendations
2. Require regular inspection of formwork and reshore installations by formwork designer
• Structural layout of formwork system
• Structural integrity, individual members & system
• General conformance with essential specifications
Formwork recommendations
2. Require regular inspection of formwork and reshore installations by formwork designer
• Structural layout of formwork system
• Structural integrity, individual members & system
• General conformance with essential specifications
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High Rise Concrete Overview
Formwork recommendations
3. Incorporate national design standards for temporary construction
• ASCE 37, Temporary Construction
• ASCE 7, Wind load criteria
4. Require formwork construction to be positively secured against uplift
• Perimeter decking
• Provide positive load path to slab
Formwork recommendations
3. Incorporate national design standards for temporary construction
• ASCE 37, Temporary Construction
• ASCE 7, Wind load criteria
4. Require formwork construction to be positively secured against uplift
• Perimeter decking
• Provide positive load path to slab
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High-rise Concrete General Site SafetyHigh-rise Concrete General Site Safety
High Rise Concrete Overview
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High Rise Concrete Overview
Observed defects, violations
• Debris dangerous to public
• Poor housekeeping practices
• Impediment to emergency egress
• Improper material storage
• Fall protection
• Missing
• Inadequate
Observed defects, violations
• Debris dangerous to public
• Poor housekeeping practices
• Impediment to emergency egress
• Improper material storage
• Fall protection
• Missing
• Inadequate
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Sample Size Unprotected EdgesAll Sites 181 78 (43%)
HRCO Observed Fall Hazard Violations
High-rise concrete general site safetyHigh-rise concrete general site safety
High Rise Concrete Overview
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High Rise Concrete Overview
High-rise concrete worker fallsHigh-rise concrete worker falls
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High Rise Concrete Overview
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High Rise Concrete Overview
Site safety recommendations
1. Effect a consistent level of knowledge and understanding among DOB inspectors
• Understand the latest NYC Building Code provisions pertinent to site safety practices
• Promote inspection consistency
Site safety recommendations
1. Effect a consistent level of knowledge and understanding among DOB inspectors
• Understand the latest NYC Building Code provisions pertinent to site safety practices
• Promote inspection consistency
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High Rise Concrete Overview
Site safety recommendations
2. Update and publish standard set of DOB inspection protocols
• Establish thresholds for violations
• Establish thresholds for Stop Work Orders
Site safety recommendations
2. Update and publish standard set of DOB inspection protocols
• Establish thresholds for violations
• Establish thresholds for Stop Work Orders
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High Rise Concrete Overview
Items subject to further study
• Utilize outrigger systems
• Maintain unbroken edge protection
• Provide hoisting platforms
• Utilize cocoon systems
Items subject to further study
• Utilize outrigger systems
• Maintain unbroken edge protection
• Provide hoisting platforms
• Utilize cocoon systems
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High-rise Concrete Special Inspection and Construction Quality
High-rise Concrete Special Inspection and Construction Quality
High Rise Concrete Overview
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High Rise Concrete Overview
Special inspection and construction quality
• Observed defects
• Ineffective special inspection
• Insufficient level of documentation
• Improper concrete testing
• Misplaced reinforcing
• Poor quality bar fabrication
Special inspection and construction quality
• Observed defects
• Ineffective special inspection
• Insufficient level of documentation
• Improper concrete testing
• Misplaced reinforcing
• Poor quality bar fabrication
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All Sites
Number of Active, Engineer-Inspected Site Observations 90
Number of Observed Quality Issues 39 (43%)
Number of Observed Critical Quality Issues 20 (22%)
HRCO‐Observed Quality Defect Rate
Special inspection and construction qualitySpecial inspection and construction quality
High Rise Concrete Overview
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High Rise Concrete Overview
Special inspection and construction quality
• Critical construction quality defects
• Improper placement of shear reinforcement
• Insufficient numbers of installed shear stirrups
• Improper column tie installation
• Improper bar engagement
• Severe bar congestion
• Improper column splice configurations
Special inspection and construction quality
• Critical construction quality defects
• Improper placement of shear reinforcement
• Insufficient numbers of installed shear stirrups
• Improper column tie installation
• Improper bar engagement
• Severe bar congestion
• Improper column splice configurations
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Special inspection and construction qualitySpecial inspection and construction quality
High Rise Concrete Overview
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Special inspection and construction qualitySpecial inspection and construction quality
High Rise Concrete Overview
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Special inspection and construction qualitySpecial inspection and construction quality
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Special inspection and construction qualitySpecial inspection and construction quality
High Rise Concrete Overview
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Special inspection and construction qualitySpecial inspection and construction quality
High Rise Concrete Overview
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Special inspection and construction qualitySpecial inspection and construction quality
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Special inspection and construction qualitySpecial inspection and construction quality
High Rise Concrete Overview
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Special inspection and construction quality
• 67 sets of stirrups required per design
• 47 sets installed
• Shear capacity reduced by ~20%
Special inspection and construction quality
• 67 sets of stirrups required per design
• 47 sets installed
• Shear capacity reduced by ~20%
High Rise Concrete Overview
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Special inspection and construction quality
• Two of 6 stirrups legs engaged
• Shear capacity reduced by ~33%
Special inspection and construction quality
• Two of 6 stirrups legs engaged
• Shear capacity reduced by ~33%
High Rise Concrete Overview
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High Rise Concrete Overview
Quality recommendations
• Enforce NYC Special Inspection Rule
• Strengthen outreach to industry regarding Special Inspection qualifications
• All Special Inspectors must hold proper registrations or certifications
Quality recommendations
• Enforce NYC Special Inspection Rule
• Strengthen outreach to industry regarding Special Inspection qualifications
• All Special Inspectors must hold proper registrations or certifications
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NYC Inspection Rule 26, Eff. June 2008
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High Rise Concrete Overview
Quality recommendations
• Provide inspector training
• Maintain institutional knowledge
• Promote uniform enforcement
• Establish clear non-conformance
Quality recommendations
• Provide inspector training
• Maintain institutional knowledge
• Promote uniform enforcement
• Establish clear non-conformance
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High-rise Concrete Worker FallsHigh-rise Concrete Worker Falls
High Rise Concrete Overview
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High Rise Concrete Overview
Construction worker falls
• Observed defects
• Insufficient leading edge protection
• Insufficient interior opening protection
• Improper or insufficient use of PFAS
• Workers ignorant of tie-off requirements
Construction worker falls
• Observed defects
• Insufficient leading edge protection
• Insufficient interior opening protection
• Improper or insufficient use of PFAS
• Workers ignorant of tie-off requirements
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High Rise Concrete Overview
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Construction worker falls
• Leading causes of construction fatalities in 2006:
• Falls: 442 out of 1,178 (38%)
• Electrocutions: 179 (15%)
• Struck by object: 206 (17%)
• Caught, trapped: 97 (8%)
Construction worker falls
• Leading causes of construction fatalities in 2006:
• Falls: 442 out of 1,178 (38%)
• Electrocutions: 179 (15%)
• Struck by object: 206 (17%)
• Caught, trapped: 97 (8%)
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High-rise Concrete Worker FallsHigh-rise Concrete Worker Falls
High Rise Concrete Overview
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High-rise Concrete Worker FallsHigh-rise Concrete Worker Falls
High Rise Concrete Overview
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HRCO Observed Violations
All Projects
Fall Hazards 43%Tie-off
Compliance 33%
High Rise Concrete Overview
Construction worker falls
• Fall hazards
• Unprotected perimeter edges
• Unprotected interior openings
• Improper barrier installation
• Tie-off violations
• Improper use of PFAS
• Failure to tie-off when required
Construction worker falls
• Fall hazards
• Unprotected perimeter edges
• Unprotected interior openings
• Improper barrier installation
• Tie-off violations
• Improper use of PFAS
• Failure to tie-off when required
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High Rise Concrete Overview
Construction worker falls
• Reduce fall incidents
• Site safety line of accountability:
• Leads to owner (not to CM)
• Non-compliant workers:
• Contractor to document remedial actions taken
• Implement fall hazard awareness campaign
Construction worker falls
• Reduce fall incidents
• Site safety line of accountability:
• Leads to owner (not to CM)
• Non-compliant workers:
• Contractor to document remedial actions taken
• Implement fall hazard awareness campaign
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• Introduction
• Background
• Risk management: two common pitfalls
• Case studies
• Miami Dade garage collapse
• NYC Gap Analysis
• Questions, discussion
• Introduction
• Background
• Risk management: two common pitfalls
• Case studies
• Miami Dade garage collapse
• NYC Gap Analysis
• Questions, discussion
Agenda
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Discussion, questions
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Discussion, questions