Bancroft Library RetrofitBancroft Library RetrofitMichael Wong, Jeffery Ho,Jennifer Ahlport, Moises MalongMichael Wong, Jeffery Ho,Jennifer Ahlport, Moises MalongCE 165 - April 19, 2007Original Bancroft LibraryOriginal Bancroft Library Collection started by Hobert Howe Bancroft and sold to UC Berkeley in 1894 Originally Built in 1949 Bancroft Library is housed in the Doe Annex Collection worth $1 billion Collection started by Hobert Howe Bancroft and sold to UC Berkeley in 1894 Originally Built in 1949 Bancroft Library is housed in the Doe Annex Collection worth $1 billionLocationLocationFundingFunding Total cost: $55 million Construction cost: $45 million $32 million funded by State for seismic upgrade $23 million funded by private donations for added security Total cost: $55 million Construction cost: $45 million $32 million funded by State for seismic upgrade $23 million funded by private donations for added securityScope Of ProjectScope Of Project Interior Shear walls with footings Remove 3 levels of tiers Renovation of interior spaces New Bookshelving System Beams New elevators Floor slabs Entrance Ramp and Stairway Upgrade HVAC, security, etc Interior Shear walls with footings Remove 3 levels of tiers Renovation of interior spaces New Bookshelving System Beams New elevators Floor slabs Entrance Ramp and Stairway Upgrade HVAC, security, etcCompanies InvolvedCompanies InvolvedArchitectEngineerContractorSubcontractorConcrete supplierArchitectEngineerContractorSubcontractorConcrete supplier Ratcliff Degenkolb McCarthy Johnson Western Gunite CEMEX Ratcliff Degenkolb McCarthy Johnson Western Gunite CEMEXProject TimelineProject Timeline Entire Project: April 2006 - April 2008 Entire Project: April 2006 - April 20082006 2007 2008Soft DemolitionApr-SeptShotcrete Shearwall Dec-FebEnd of Project AprilBeam Casting Jan-AprHard DemolitionAug-FebBasement Slab Pouring beginsMayOutside Stairs and Ramps begin DecDemolitionDemolition Soft Demolition: April - September 2006 Walls, doors, mechanical systems Hard Demolition: August 2006 - February 2007 Done between 6pm and 2am Floors, tiers, elevator shafts Check for poisonous content like asbestos & mercury Soft Demolition: April - September 2006 Walls, doors, mechanical systems Hard Demolition: August 2006 - February 2007 Done between 6pm and 2am Floors, tiers, elevator shafts Check for poisonous content like asbestos & mercuryNew Elevator ShaftsNew Elevator Shafts Marked off dimensions Jackhammered slab starting at center to edge Cut off rebar with concrete saw Sanded vertical faces Marked off dimensions Jackhammered slab starting at center to edge Cut off rebar with concrete saw Sanded vertical facesSeismic Upgrade:Shear WallSeismic Upgrade:Shear Wall Originally there was no form of lateral resistance in the building Primary Method forSeismic Stability Added from basement to 4th floor Originally there was no form of lateral resistance in the building Primary Method forSeismic Stability Added from basement to 4th floorShear Wall - TimelineShear Wall - Timeline Shear wall placement was started Dec. 2006 Each wall was shot in a single day to avoid cold joints Each floor took 1-2 weeks to complete They started on the basement floor and worked their way up to the 4th floor Shear wall placement was started Dec. 2006 Each wall was shot in a single day to avoid cold joints Each floor took 1-2 weeks to complete They started on the basement floor and worked their way up to the 4th floorShotcrete - What is it?Shotcrete - What is it? Concrete shot out of nozzle with pneumatic air Sprayed in layers approximately 4’’ thick each pass until reaching desired thickness Placement consolidates concrete so no vibration required Concrete shot out of nozzle with pneumatic air Sprayed in layers approximately 4’’ thick each pass until reaching desired thickness Placement consolidates concrete so no vibration requiredShear Wall: Mix DesignShear Wall: Mix Design Type II/V cement used f’c= 5000 psi Slump of 2’’ desired Unit weight = 145.4 lbs/cu ft W/C ratio of .42 15% fly ash (F) used 1/2’’ aggregate used Type II/V cement used f’c= 5000 psi Slump of 2’’ desired Unit weight = 145.4 lbs/cu ft W/C ratio of .42 15% fly ash (F) used 1/2’’ aggregate usedShear Walls - PreppingShear Walls - Prepping Both columns & beams had to be prepped before a shear wall could be placed Columns had to be chipped until rebar was exposed Base of beams had to be chipped out Rebar was epoxied into existing columns  Both columns & beams had to be prepped before a shear wall could be placed Columns had to be chipped until rebar was exposed Base of beams had to be chipped out Rebar was epoxied into existing columnsMoat WallMoat Wall Monolithic wall inside perimeter of exterior wall In place on 1st floor to protect collection against moisture Fans had to be running during construction to make sure that walls do not absorb VOCs Problems: cracks & shotcrete issues Monolithic wall inside perimeter of exterior wall In place on 1st floor to protect collection against moisture Fans had to be running during construction to make sure that walls do not absorb VOCs Problems: cracks & shotcrete issuesMoat Wall - CracksMoat Wall - Cracks Found cracks running along rebar in moat wall Afraid of decreased strength, so took 3 core samples to test All samples came up above required strength Refinish Face Found cracks running along rebar in moat wall Afraid of decreased strength, so took 3 core samples to test All samples came up above required strength Refinish FacePoor Shotcrete PlacementPoor Shotcrete Placement Voids behind rebar in moat wall Due to shotcrete spraying perpendicular to rebar Avoided in newly placed shotcrete Voids behind rebar in moat wall Due to shotcrete spraying perpendicular to rebar Avoided in newly placed shotcreteBeam FrameworkBeam Framework Beam shoring started on bottom floor After 7 days of curing additional shoring was added to support floor above Beam shoring started on bottom floor After 7 days of curing additional shoring was added to support floor