Department of Public WorksSELECTION OF STRUCTURAL RETROFIT APPROACH FOR CENTRAL LIBRARY EARTHQUAKE RETROFIT AND BUILDING REPAIRS PROJECTCity CouncilAugust 21, 2023Item #10 Department of Public WorksPresentation Overview•Background>Building History>Serving the Community>Building Evaluation & Closure>Design Team & Appointed Committees•Development of Earthquake Retrofit Approaches>Project Goals & Design Standards>Earthquake Repair Approaches>Structural Performance Comparison •Cost Plan•Evaluation Matrix•Public Outreach & Commissions•Next Steps & Schedule•Recommendation2 Department of Public Works
BACKGROUND
3 Department of Public WorksCentral Library Building HistoryPillar of Planned Civic Center, along with City Hall & Civic Auditorium•First to be constructed: 1925 – 1927•120,000 sf floor space•Designed by renowned architects, Myron Hunt & H.C. Chambers•National Register of Historic Landmarks•Building's systems remain original to the building4 Original Bennett Plan forthe Pasadena Civic Center
Department of Public WorksCentral Library Building HistoryHistoric Character-Defining Features•Exterior>Mediterranean Revival style>Walled entrance courtyard with central fountain>Red clay tile roofs>Stucco with cast stone decorative trim5
Department of Public WorksCentral Library Building HistoryHistoric Character-Defining Features•Interior>Circulation Hall>Built-in casework with integrated air conditioning delivery system>Interior finishes including cork tile flooring, paneled wood wainscoting, textured acoustic plaster walls, coffered wood ceiling, and decorative light fixtures6
Department of Public WorksServing the Community Home to wide variety of programs and services •30,000-40,000 community members attended events annually >Storytimes>Author visits>Cultural events>Recitals and plays•Home to the Office of the Young Child•Hub for historical archives and 300,000 items that cannot be accessed at branch libraries7
Department of Public WorksBuilding Evaluation & Closure•Initiated in 2020 – Central Library Building Systems & Structural Assessment project (71910)•April 2021- KPFF Consulting Engineers structural assessment•Visible cracking•May 3, 2021 – City Officials ordered library closed•Independent evaluation by Nabih Youssef & Associates 8
Department of Public WorksDesign Team & Stakeholder Committees•Design Team – Contract awarded January 2023>Gruen Associates & 13 sub-consultants, includingKPFF Structural EngineersHistoric Resources GroupMGAC Cost Estimator•City’s peer review & advisory consultantsNabih Youssef & AssociatesKrakower & Associates Structural Engineers•City’s independent site evaluation consultantsWJE – Materials TestingGeoPentech – Geotechnical Testing9 Department of Public WorksDesign Team & Stakeholder CommitteesTechnical Oversight Committee•Appointed by Mayor Victor Gordo•Committee responsibilities>Review reports, findings and retrofit approaches and provide advice/feedbackProgramming Committee•Appointed by Interim City Manager, Cynthia Kurtz•Committee responsibilities:>Recommend next steps and path forward to enhance offerings at Central Library as a result of the necessary retrofit and restoration work>Issued the Central Library Community Programming Committee Report on February 27, 202310 Department of Public Works
DEVELOPMENT OF EARTHQUAKE RETROFIT APPROACHES11
Department of Public WorksProject Goals & Design StandardsProject Goals and ObjectivesEARTHQUAKE REPAIRS– Improve seismic performance to allow the building to have greater resilience to earthquakesHISTORIC IMPACTS – Preserve the building’s historic fabric, its character defining features, and its historic listingsACCESSIBILITY– Adopt universal access principles to accommodate different levels of ability and mobilityPUBLIC BENEFIT – Re-occupy building as quickly as reasonable so that patrons can have use of the library and its servicesBUILDING SYSTEMS – Ability to upgrade building systems (HVAC, electrical, plumbing, fire alarm and fire sprinklers, technology) without significant impactsFUNCTION / FLEXIBILITY – Ability to utilize spaces as desired into the futureCOST EFFECTIVENESS – Lowest cost that meets earthquake performance goals12 Department of Public WorksProject Goals & Design Standards•Design Standards>Pasadena Municipal Code – URM Ordinance Section 14.06.030>California Historic Building Code>California Existing Building Code>Secretary of the Interior's Standards for Historic Buildings>ASCE41-17 – Industry standard for seismic evaluation and retrofit of existing buildings13 Department of Public Works
14 Earthquake Retrofit Approaches
PLASTERORIGINALMILLWORKINTEGRATEDHVAC DUCTOUTERWYTHEINNERWYTHEORIGINAL MILLWORKWYTHESExisting Key Features Department of Public WorksEarthquake Retrofit ApproachesI. Baseline Approach•Removes limited amounts of inner-brick wythe to install concrete columns to support remaining brick, floors, and roof•Permanent formwork to be installed and remain in place to support backing of the columns•Meets minimum code requirements for historic URM retrofit•Does not meet basis of design equivalent to newbuilding performance•Pros>Lowest cost>Shorter construction duration•Cons>Lowest level of structural performance of three approaches>Constructability concerns15 Department of Public Works
I. Baseline Approach
16 Earthquake Retrofit ApproachesEXISTING WALL SECTIONREMOVE FINISHES
REMOVE SECTIONS OF INTERIOR WYTHEFOR NEW COLUMNS
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I. Baseline Approach (continued)
17 Earthquake Retrofit ApproachesCONSTRUCT NEW COLUMNSREPLACE INTERIOR FINISHES AND RE-INSTALL ORIGINAL MILLWORK
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Earthquake Retrofit Approaches
18 NEW CONCRETE COLUMNS(APPROX. 415)
Department of Public WorksEarthquake Retrofit ApproachesII. Concrete Shear Wall Approach•Removes inner-brick wythe and replaces it with a concrete shear wall supporting out wythe of brick, floors, and roof•Permanent formwork to be installed and remain in place to support backing of the shear walls•Meets basis of design equivalent to newbuilding performance•Pros>Shorter construction duration (same as Baseline Approach)>Common and proven engineering and construction approach>Lowest cost approach that meets basis of design•Cons>Greater potential for damage and longer recovery time after major earthquake compared to Base Isolation Approach19 Department of Public Works
II. Concrete Shear Wall Approach
20 Earthquake Retrofit ApproachesEXISTING WALL SECTIONREMOVE FINISHESREMOVE INTERIOR WYTHE FOR NEW SHEAR WALLS Department of Public Works
II. Concrete Shear Wall Approach (continued)
21 Earthquake Retrofit ApproachesCONSTRUCT NEW SHEAR WALLREPLACE INTERIOR FINISHES AND RE-INSTALL ORIGINAL MILLWORK
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22 Earthquake Retrofit Approaches
NEW CONCRETE SHEAR WALLS(APPROX. 2500 LF)
Department of Public WorksEarthquake Retrofit ApproachesIII. Base Isolation Approach•Removes limited amounts of inner-brick wythe and replaces with concrete columns to support remaining brick, floors, and roof (similar to Baseline Approach)•Utilizes base isolators under ground floor around perimeter and under new concrete columns•Permanent formwork to be installed and remain in place to support the backing of the columns•Exceeds basis of design equivalent to newbuilding performance23 Department of Public WorksEarthquake Retrofit ApproachesIII. Base Isolation Approach (continued)•Pros>Quickest recovery time after major earthquake compared to other approaches>Reduces magnitude of ground motion impacts and potential for damage in moderate and major earthquakes•Cons>Reduces basement’s usable square footage compared to other approaches>Highest cost>Constructability concerns>Increases duration of design and construction and, therefore delays project completion24 Department of Public Works
III. Base Isolation Approach
25 Earthquake Retrofit ApproachesEXISTING WALL SECTIONREMOVE FINISHESREMOVE SECTIONS OF INTERIOR WYTHEFOR NEW COLUMNS AND SECTION OF BASEMENT BEARING WALL FOR BASE ISOLATORS
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III. Base Isolation Approach (continued)
26 Earthquake Retrofit ApproachesCONSTRUCT NEW COLUMNS AND INSTALL NEW BASE ISOLATORSREPLACE INTERIOR FINISHES AND RE-INSTALL ORIGINAL MILLWORK
Department of Public WorksEarthquake Retrofit Approaches 27 NEW BASE ISOLATORS(APPROX. 100)
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Structural Performance Comparison
28 Department of Public Works
COST PLAN29
Department of Public WorksCost Plan•MGAC – Certified Cost Estimator (26 years experience)•Cost Plan includes:>Construction; contingencies; cost escalations; project/construction management; inspection & move-in>Cost ranges account for predictable market condition escalations at time of projected construction>Actual costs may vary should market conditions differ significantly from predicted at time of construction •Design team tasked to estimate the most cost-effective solutions for the following:>Structural retrofit approaches & constructability>Repair and upgrade century-old infrastructure systems (HVAC, electrical, plumbing)>Serve the public into the next century Department of Public Works
Cost Plan
31**If deferred, future cost in five years: $91M
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APPROACH COMPARISON MATRIX32
Department of Public WorksApproach Comparison Matrix
33 PROJECT GOALSBASELINE APPROACHSHEAR WALL APPROACHBASE ISOLATION APPROACHEARTHQUAKE REPAIRS - Performance equivalent to a new building HISTORIC IMPACTS - Ability to maintain character defining features and historic listing ACCESSIBILITY - Ability to make building meet universal design and ADA PUBLIC BENEFIT - Time needed to restore Library to Public Use BUILDING SYSTEMS - Ability to upgrade the building systems without significant impacts FUNCTION/FLEXIBILITY - Ability to utilize spaces in the manner desired without impacts COST EFFECTIVENESS - Lowest cost that meets earthquake performance Department of Public Works
PUBLIC OUTREACH & COMMISSIONS34
Department of Public WorksPublic Outreach & CommissionsCommunity EventsMay 24, 2023 – Community Outreach Meeting @ Jefferson SchoolMay 31, 2023 – West Pasadena Residents’ Association Annual Meeting @ Maranatha High SchoolJuly 8, 2023 – Farmers’ Market Pop-Up Event @ Victory ParkJuly 15, 2023 – Colorado Street Bridge Party Pop-UpAugust 1, 2023 – National Night Out Pop-Up @ Civic Center35 Department of Public WorksPublic Outreach & CommissionsCommission Presentations•July 18, 2023 – Historic Preservation Commission•July 19, 2023 – Library Commission•July 25, 2023 – Design Commission•Each commission commented and supported staff’s recommendation of proceeding with Concrete Shear Wall Approach36 Department of Public Works
NEXT STEPS & SCHEDULE
37 Department of Public WorksNext Steps•Proceed with environmental & final design•Further structural analysis & materials testing>Seek opportunity to minimize impact to building’s structure and its historic fabric•Find ways to economize for cost efficiency•Continue community outreach•Present funding strategy to City Council38 Department of Public WorksProject Schedule•Schematic Plans & Cost Estimate•60% Design Plans & Cost Estimate•Potential Bond Measure•100% Plans & Plan Check•Bid & Construction Contract Award (pending construction funding)•Anticipated Construction Duration•Projected Construction Completion39Spring 2025November 2024Spring 2024Fall 2023Summer 202530-36 monthsLate 2028 Department of Public Works
RECOMMENDATION
40 Department of Public WorksRecommendationDirect staff to proceed with the Concrete Shear Wall structural retrofit approach for the Central Library Earthquake Retrofit and Repair project. 41 Department of Public WorksThank you!42