HOW TO EVALUATE BUILDINGS AND DETERMINE RETROFIT COSTS

how to evaluate buildings

and determine retrofit costs

• David Bell

PJHM Architects, Inc.

• Young Nam

• Daniel Traub

Thornton Tomasetti

HOW TO EVALUATE

BUILDINGS AND

DETERMINE RETROFIT

COSTS

David Bell, AIA, PJHM Architects Inc. Young Nam, S.E., Thornton Tomasetti Daniel Traub, S.E., Thornton Tomasetti

REGULATIONS

„ ASSEMBLY BILL (AB) 300, 1999 (CORBETT)

yREQUIRED DGS TO DO AN INVENTORY OF PUBLIC SCHOOL BUILDINGS THAT TO NOT MEET 1976 U.B.C.

y1976 U.B.C. ADDED SEISMIC PROVISIONS IN REACTION TO RECENT EARTHQUAKES

REGULATIONS

„ DGS REPORT, ISSUED NOVEMBER, 2002

yINVESTIGATED BUILDINGS BUILT BETWEEN 1933 AND 1978

– 1933 - PASSAGE OF THE FIELD ACT AS

REGULATIONS

– 1978- ADOPTION OF 1976 U.B.C, SO ALL

BUILDINGS APPROVED AND BUILT AFTER 1978 ASSUMED TO BE COMPLIANT

– WOOD FRAMED BUILDINGS EXEMPT FROM

INVENTORY: 80% OF BUILDINGS, 379M SQ. FT.

– BUILDINGS INVENTORIED ARE CONCRETE

TILT-UP AND/OR HAVE NON-WOOD FRAMED WALLS

REGULATIONS

– BUILDINGS SORTED INTO TWO CATEGORIES: – CATEGORY 1: EXPECTED TO PERFORM

WELL IN AN EARTHQUAKE

– 2,122 BUILDINGS, 27M SQ. FT.

– CATEGORY 2: NOT EXPECTED TO PERFORM

AS WELL AS CATEGORY 1 BUILDINGS IN AN EARTHQUAKE

REGULATIONS

„ PROPOSITION 1-D, PASSED NOVEMBER, 2006 y$7.3 BILLION FOR K-12 CONSTRUCTION y$199.5 MILLION AVAILABLE FOR SEISMIC

RETROFITS

yREGULATIONS BEING DEVELOPED TO DETERMINE HOW AND TO WHOM THOSE FUNDS ARE

DISTRIBUTED

– DSA HAS IDENTIFIED 142 BUILDINGS AS BEING

THE ‘MOST VULNERABLE’ „ CALIFORNIA BUILDING CODE

y2001 EDITION CURRENTLY, 2007 EDITION EFFECTIVE JANUARY 1, 2008

SEISMIC MITIGATION PROGRAM 1. ASSEMBLE TEAM

2. INITIAL STUDY

¾ Establish Evaluation Approach

¾ Verify Buildings

¾ Establish Seismic Performance Objectives 3. EVALUATION ¾ Different Approaches ¾ Cost Estimate ¾ Prioritize 4. POST EVALUATION ¾ Modernizations 5. FUNDING 6. IMPLEMENTATION PRESENTATION FOCUS

INITIAL STUDY

1. VERIFY THE FOLLOWING FOR THE BUILDINGS 1. Building exists / Still part of District

2. No previous seismic retrofit * 3. Verify Category 1 or 2 (or neither)

2. ESTABLISH SEISMIC PERFORMANCE OBJECTIVES

¾ Damage Control

¾ Life Safety

¾ Collapse Prevention

3. DEFINE SCOPE OF WORK

¾ Evaluation Approach

¾ Cost Estimate Approach

* MAY NEED INPUT FROM STRUCTURAL ENGINEER

PERFORMANCE LEVELS

EVALUATION TYPES

1. PROPOSITION 1D APPROACH

(WITH OR WITHOUT FUNDING)

2. FEMA 310 / ASCE 31 ASSESSMENT 3. CURRENT CODE

EVALUATION CAN ALSO BE A HYBRID OF THE ABOVE APPROACHES

PROP 1D APPROACH

‰ BASED ON AB 300 REPORT & PROP 1D

‰ ADDRESSES ONLY “MOST VULNERABLE” BUILDINGS ‰ WILL NOT IDENTIFY OTHER BUILDINGS THAT MAY

HAVE SEISMIC DEFICIENCIES AND LIFE SAFETY RISKS

SUGGESTED CRITERIA BY DSA TO IDENTIFY “MOST VULNERABLE” BUILDINGS *

CRITERIA 2 Category 2 and Building Type

C1, PC1A, PC2 OR URM CRITERIA 1 Site Acceleration > 1.55 g

CRITERIA 3 Occupied by Students & Teachers

CRITERIA 4 Report from Structural Engineer

(Assessing Collapse Prevention)

Does Not Qualify for Prop 1D Funding

NO

Apply for Prop 1D Yes Yes Yes Yes NO NO NO

*State Allocation Board Implementation Committee Meeting August 3, 2007

CRITERIA 1

CRITERIA 1

CRITERIA 2

Definitions based on DSA study pursuit to AB 300:

“SEISMIC SAFETY INVENTORY OF CALIFORNIA PUBLIC SCHOOLS”

MOST VULNERABLE BUILDING TYPES IN CATEGORY 2

C1 - Concrete Moment Frame

PC1A – Precast/Tilt-Up Concrete Shear Wall with Flex. Diaphragm PC2 – Precast Concrete Frame and Concrete Shear walls

URM – Unreinforced Masonry Bearing Wall

(Includes those previously retrofitted with gunite walls) (Note this is only 4 of 12 building types identified in Category 2)

BUILDING TYPES

C1 PC1A

PC2 _URM

CRITERIA 3 & 4

‰ OCCUPIED BY STUDENTS AND TEACHERS

¾ Verify the usage of the building

‰ REPORT FROM STRUCTURAL ENGINEER *

¾ The lateral force resisting system does not meet collapse prevention performance

¾ Provide specific deficiencies and reasoning that the building has a potential for catastrophic collapse

* Probably Requires A FEMA 310 / ASCE 31 and or FEMA 356 / ASCE/SEI 41 Type Assessment

FEMA 310 / ASCE 31 APPROACH

(The selected type will depend upon evaluation objectives)

1. Category 2 Buildings Only

¾ Addresses “Most Vulnerable” buildings identified by DSA

¾ May want to first verify that buildings classified correctly to Category 2

FEMA 310 / ASCE 31 APPROACH

2. All Category 1 & 2 Buildings

¾ Provides comprehensive understanding of seismic risk for the District

¾ Identifies other “Life Safety” concerns (Including Category 1 buildings)

¾ Provides opportunity to implement other “Life Safety” retrofits into modernization program

¾ Able to obtain total cost for retrofit of all buildings

¾ Does not necessarily bring building up to current structural code

FEMA 310 / ASCE 31 APPROACH

3. All Buildings

¾ Similar to previous except, includes buildings not reviewed during AB 300 study (wood frame & post 1978 buildings)

¾ Verifies that buildings were correctly classified

CURRENT CODE APPROACH

‰ SOME DISTRICTS WISH TO BRING BUILDING UP TO

CURRENT CODE

‰ TYPICALLY MORE EXPENSIVE, BUT NOT

NECESSARILY

‰ NOT ALWAYS POSSIBLE

‰ STRUCTURAL ENGINEER PERFORMING RETROFIT

MAY BE MORE FAMILIAR WITH CURRENT CODE THAN FEMA 356 / ASCE 41

ESTABLISHING COSTS

‰ PER DSA (AS RECOMMENDED TO SAB 8/3/07): ‰ $60 PER SQ. FT. COST TO RETROFIT

‰ 142 IDENTIFIED BUILDINGS = 1,760,000 SQ. FT. ‰ = $106 MILLION IN CONSTRUCTION COSTS ‰ SOFT COSTS ESTIMATED AT 29%, $31 MILLION

‰ = TOTAL OF $137 MILLION (2002 DOLLARS)

‰ ADJUSTED TO $169 MILLION (2007 DOLLARS) ‰ DOUBLE COSTS TO ACCOUNT FOR OTHER

REQUIRED WORK = $338 MILLION

‰ $338 MILLION / 142 ‘MOST VULNERABLE’ =

$2.38 MILLION PER BUILDING (STATE + LOCAL FUNDS)

ASSESSING COSTS

¾VERY SITE SPECIFIC!

¾DEPENDS ON SITE, BUILDINGS, EVALUATION FINDINGS AND MITIGATIONS

‰DSA REQUIRED SCOPE OF WORK

¾ACCESS COMPLIANCE & FIRE LIFE SAFETY UPGRADES REQUIRED

ASSESSING COSTS

- CBC 1134B.2.1 “A PRIMARY

ENTRANCE TO THE BUILDING OR FACILITY AND THE PRIMARY PATH OF TRAVEL TO THE SPECIFIC AREA OF ALTERATION, STRUCTURAL REPAIR OR ADDITION, AND SANITARY

FACILITIES, DRINKING FOUNTAINS, SIGNS AND PUBLIC TELEPHONES SERVING THE AREA”

‰MATERIAL COSTS

ASSESSING COSTS

¾SPATIAL IMPACTS ¾CLASSROOM IMPACTS

PRIORITIZE

‰ PRIORITIZE “MOST VULNERABLE” BUILDINGS BASED ON AB 300 CRITERIA

‰ IDENTIFY RELATIVELY EASY FIXES

‰ ALLOW TO MAKE AN INFORMED DECISION / PLANS

POST EVALUATION

‰ DO YOU HAVE A PROJECT (FUNDING) ?

‰ DSA ESTIMATE - $2.38 MILLION PER BUILDING ‰ 60% STATE / 40% LOCAL: $1.43M STATE / $950,000

LOCAL

‰ DISTRICT SPECIFICS

‰ STATUS / SOURCE OF LOCAL FUNDING?

‰ PURSUE HARDSHIP?

PROGRAM THE PROJECT

FULL MODERNIZATION? ¾DSA REQUIRED SCOPES

¾FULL MODERNIZATION BENEFITS

PLAN THE PROJECT

‰MODERNIZATION WITH GREATER STRUCTURAL

COMPONENT

‰PROJECT TIMING / SCHEDULE

¾SUMMER VACATION OR LONGER? ¾MATERIAL LEAD TIMES

CASE STUDIES

RESOURCES

1. USGS Seismic Acceleration Maps

http://earthquake.usgs.gov/research/hazmaps/

2. Seismic Safety Inventory of California Public Schools

(AB 300 Report)http://www.dsa.dgs.ca.gov/Pubs/default.htm

3. FEMA 424 Design Guide for Improving School Safety in

Earthquakes, Floods and High Winds