David Post v. Crane Rigging Corp.

Preliminary Reconstruction Presentation

Drake Exhibits 2-26-08

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Blevins Building Supply Co. - Site Plan

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Accident site overview

Blevins Building Supply Co. - Site Plan

US highway 21

main office / storenew warehouseconstruction

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Plan View - Blevins Building Supply Co.

US highway 21

main office / storenew warehouse construction

date of accident - 00-00-00

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New warehouse construction

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New warehouse construction

roof trusses set exterior wall framing

stack ofroof trussesto be set

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New warehouse construction

Trusses are lifted by crane and set on top of exterior wall frame

show crane

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Accident Sequence

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Trusses are stacked in parking lot

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Trusses are rigged to crane using a spreader bar approx. 20’ long

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Spreader bar is attached to truss with chains at each end

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Truss is lifted to vertical from stack

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DRAFTTruss bends and tilts when lifted off stack

A tag line is used to control movement of the truss

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DRAFTTruss bends and flops around while being moved to building

Truss is swung around to south end of building

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Truss is moved to the north

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Worker positions on scissor lifts

David Post &Roger Billings

Randall ________

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Truss is lowered toward final position

David Post &Roger Billings

Randall ________

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Truss breaks at attachment point severely injuring David Post

David Post &Roger Billings

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Accident is Result of Improper Rigging of Truss

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Rigging Trusses

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Accident rigging dangerously inadequate for 80 foot long truss

Spreader baris too short

80 Feet

Spreader bar is too high on truss

Spreader baronly attachedat ends

Chain angle more than 60º

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Proper method for rigging an 80 Foot Long TrussFrom BCSI-B1 Guide for Handling, Installing, Restraining & Bracing of Trusses

80 Feet

Spreader bar is 2/3 to 3/4 truss length

Locate spreader bar at or above mid-height

Attachment points to truss at a maximum of 10 foot intervals

Chain angle 60º or less

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1. Calculation of Stress and Deformation of the Truss During Lifting Operations

ANSYS Finite Element Analysis computer software used for all results

Actual incident truss geometry and material propertiesincorporated in analysis

Truss lifting points obtained from witness statements

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1. Calculation of Stress and Deformation of the Truss During Lifting Operations

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QuickTime™ and aMicrosoft Video 1 decompressorare needed to see this picture.

2. Animation of Truss Deformation During Lifting Operation

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3. Animation of Truss Deformation During Lifting Operation - close up of maximum stress location

QuickTime™ and aMicrosoft Video 1 decompressorare needed to see this picture.

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4. Truss Deformation as it Leaves the Truss Stack

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Measure actual load-displacement response of an exemplar truss at Tru-Line Truss Company

5. Validation of the Computer Model of the Truss

Compare the measured values with that predicted by the computer model

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5. Validation of the Computer Model of the Truss

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Modeling Stresses in Wooden Trusses During Lifting and Moving

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Trusses are improperly rigged using a spreader bar approx. 20’ long

Improper method of rigging

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Stress shown in truss structure as truss is lifted off pile

Highest stress is at the point of attachment

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Truss bends and twists when lifted using inadequate rigging

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Truss breaks at point of attachment to spreader bar

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Trusses are rigged to crane using a spreader bar approx. 60’ long

Proper method of rigging

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Stress shown in truss structure as truss is lifted off pile

Stress shown in truss structure as truss is moved to building

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Stress shown in truss structure as truss is set and fastened to top plate

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Drake Exhibits - Demonstrative Evidence Services1275 Main StreetBrewster, MA 02631

508-255-8194www.Drake-Exhibits.com

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