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Modesto Junior College Science Community Center. Design Challenges. Floor Vibration Criteria Telescope Vibration Criteria Horizontal Drift Joint Spiral Stairs Steel Subcontractor – Walked Away Moment Frame – Grade Beam Interface Planetarium Door Widening. Floor Vibration Criteria.
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Design Challenges • Floor Vibration Criteria • Telescope Vibration Criteria • Horizontal Drift Joint • Spiral Stairs • Steel Subcontractor – Walked Away • Moment Frame – Grade Beam Interface • Planetarium Door Widening
Floor Vibration Criteria • Lab Consultant: • W3 x 18 with 4 ½” normal weight concrete over the top of flutes; total thickness = 7 ½”. • Vibration Criteria was Excessive – Added an additional $1,000,000 in steel floor beam cost to the project – $500,000 per floor. • Compromise Solution – District not having vibration issues in current facility: • Floor Beams: • Design for 125 psf Live Load, Non-reducible • Limit deflection to: • L/240 DL + LL • L/360 LL Only • Design floor beams as “non-composite” then install Nelson studs @ 12” oc. Foundation Model: Design for 80 psf Live Load (reducible) & 20 psf partition load (Designs like this give engineers a bad name!)
Steel Subcontractor Disappeared! Total number of subcontractors on the project =63 Number of subcontractors that filed for bankruptcy during construction of the Science Community Center = 33 Impact of steel subcontractor going away: $2.4 million 4 ½ month project delay Steel pieces scattered across the project site.