Building Name: Evaluator: TABSite Specific Ground Motion Study? Yes, 2015 Update to the Site-Specific Seismic Hazard Analyses and Development of Seismic Design Ground Motions BSE-1N

Building Name: Evaluator: TAB

CAAN ID: 1229 Date: 03/12/19

BUILDING DESCRIPTION

General

This building finished construction in 1991 and is mostly below grade on a level site. The building has

one story above grade with a basement below and is approximately 32 feet tall from the top of

foundation. The building is generally rectangular in shape with a footprint of about 256 feet in the NS

direction and 156 feet in the EW direction below grade and 96 feet North South and 180 feet East West

above grade. The building area is approximately 52,000 square feet

.

Structural System

The gravity load structural system consists of a composite steel framing system supported by various

sized steel wide flange framing members with steel columns above the ground level, rectangular

concrete columns below the ground level, and bearing walls at both stories. The slab is 3 in. metal deck

with 4 ½” of normal weight concrete fill. The foundation is a 8” slab on grade with spread footings

underneath the columns and strip footings underneath the walls. The lateral load system consists of

concrete shear walls with concrete slabs on metal deck serving as horziontal diaphragms.

Building Condition

Good, no deteoriation observed.

Date of Site Visit: 03/28/2019, Ray Pugliesi & Torrey Bolden, Degenkolb Engineers

Limitations of walk-through: Part of the basement level

.

SITE INFORMATION

Site Class (A-F): C Basis: Geologic Hazards and Site Classification, Geomatrix Plate 2

Site Specific Ground Motion Study? Yes, 2015 Update to the Site-Specific Seismic Hazard Analyses and

Development of Seismic Design Ground Motions

BSE-1N Spectral Accelerations: Basis: 2015 Site Specific Report Table 5 for 36-75 ft Soil

SDS: 2.40 SD1: 0.71

BSE-2E Spectral Accelerations: Basis: 2015 Site Specific Report Table 6 for 36-75 ft Soil

SXS: 3.15 SX1: 1.05

Level of Seismicity: High

Performance Level: Collapse Prevention Structural Performance

Geologic Hazards:

Fault Rupture No Basis: Earthquake Zones of Required Investigation- Oakland West Quadrangle

https://maps.conservation.ca.gov/cgs/informationwarehouse/regulatorymaps/

Liquefaction No Basis: Earthquake Zones of Required Investigation- Oakland West Quadrangle


Landslide No Basis: Earthquake Zones of Required Investigation- Oakland West Quadrangle


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CAAN ID: 1229 Date: 03/12/19

PREVIOUS RATINGS SUMMARY

1. Good – 1997 Preliminary Seismic Evaluation (SAFER), Forrell Elsesser Engineers, Inc.

DOCUMENTATION

Architectural Drawings:

Structural Drawings:

Seismic Evaluations: “1997 Preliminary Seismic Evaluation (SAFER)”, Forell Elsesser Engineers,

Inc., 08/26/1997, FEMA-178 Structural Checklist

Geotechnical Reports:

Other Documents: N/A

CONSTRUCTION DATA

LATERAL-FORCE-RESISTING SYSTEM

Longitudinal Transverse

ASCE 41-17 Building Type: C2: Conc. SW C2: Conc. SW

Diaphragms: Metal Deck with Conc. Top. Metal Deck with Conc. Top.

Vertical Elements: WF’s & Conc. Columns WF’s & Conc. Columns

Connections: Standard steel connections Standard steel connections

Details: S7.01,S7.02 S7.01,S7.02

Estimated Fundamental Period, T (sec): 0.266 0.266

BSE-2E Spectral Acceleration, Sa: 3.15g 3.15g

Modification Factor, C: 1.2 (C2 – Table 4-7) 1.2 (C2 – Table 4-7)

Building Weight, W (kips): 13,398 13,398

Seismic Base Shear, V (kips): 50,643 50,643

System Modification Factor, Ms: 4.5 4.5

Gravity Load Structural System: Composite WF steel framing, and concrete columns below grade lvl

Exterior Transverse Walls: Concrete wall Opening(s)? Yes

Exterior Longitudinal Walls: Concrete wall Opening(s)? Yes

Roof Materials/Framing: 3” Metal Deck with 4 ½” Concrete Fill/Steel Wide Flange Beams

Intermediate Floors/Framing: 3” Metal Deck with 4 ½” Concrete Fill/Steel Wide Flange Beams

Ground Floor: 8” Slab on Grade

Columns: W8’s on top of conc. columns Foundation: Spread footings

General Condition of Structure: Good

Evidence of Settling?: No

Special Features & Comments:

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CAAN ID: 1229 Date: 03/12/19

Significant Structural Deficiencies, Potentially Affecting Seismic Performance Level Designation:

Lateral System Stress Check (wall shear, column shear or flexure, or brace axial as applicable)

Load Path

☐ Adjacent Buildings

☐ Weak Story

☐ Soft Story

Geometry (vertical irregularities)

☐ Torsion

☐ Mass – Vertical Irregularity

☐ Cripple Walls

☐ Wood Sills (bolting)

☐ Diaphragm Continuity

☐ Openings at Shear Walls (concrete or masonry)

☐ Liquefaction

☐ Slope Failure

☐ Surface Fault Rupture

☐ Masonry or Concrete Wall Anchorage at Flexible Diaphragm

☐ URM wall height to thickness ratio

☐ URM Parapets or Cornices

☐ URM Chimney

☐ Heavy Partitions Braced by Ceilings

☐ Appendages

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CAAN ID: 1229 Date: 03/12/19

OVERALL SEISMIC DEFICIENCIES & EXPECTED SEISMIC PERFORMANCE

The below item has been identified as non-compliant:

1. Discontinuous Shear Wall: Discontinuous shear walls make up approximately half of the lateral

system in both directions at the first story above grade. These shear walls are supported by

16”x16” concrete columns at each end of the shear wall. These columns are axially loaded by

the shear wall demand above and limited by the wall capacity. The columns have an axial DCR of

2.3 when considering the demand resulting from the capacity of the wall. The overstressing of a

column is a potential partial collapse hazard.

2. Shear Stress Check: The shear walls at the first level are overstressed in the transverse direction

based on the quick check procedure. These walls are part of the basement level, and the

amount of overstressing is low. This is not expected to be a collapse hazard.

3. Horizontal Geometry: The wall along the west elevation has a reduction in horizontal dimension

greater than 30% from the first story to the basement. This geometric irregularity may affect the

dynamic response of the structure and lead to unexpected local force concentrations. Because

of the short, stout quality of this building it is not expected that this structure will have

significant higher mode contributions.

Based on the above deficiencies, this structure has been assigned an SPL rating V.

No non-structural deficiencies have been identified for this structure.

Recommended Next Steps: It is recommended that a Tier 2 is preformed to better understand the force

distribution and ductility demand of the structure. It is possible that with a better understanding of

these demands and distributions these deficiencies may be resolved.

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CAAN ID: 1229 Date: 03/12/19

Seismic Retrofit Concept Sketches/Description (only if above-listed rating is V or greater):

The discontinuous shear wall is the main deficiency that may limit this structure from preforming and

achieving a better seismic rating. This deficiency can be mitigated by placing shear walls underneath the

discontinuous shear walls to alleviate the demands on the column or strengthen the columns. Below is a

graphic showing the discontinuous shear walls. The columns of greatest concern are the ones located

under shorter wall segments as these may experience increased overturning demands.

Figure 1 Locations of Discontinuous Shear Wall

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CAAN ID: 1229 Date: 03/12/19

Appendices

A. Additional Photos

B. ASCE 41-17 Tier 1 Checklists (Structural)

C. UCOP Seismic Safety Policy Falling Hazards Assessment Summary

D. Quick Check Calculations

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CAAN ID: 1229 Date: 03/12/19

APPENDIX A

Additional Photos

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CAAN ID: 1229 Date: 03/12/19

APPENDIX B

ASCE 41-17 Tier 1 Checklist (Structural)

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CAAN ID: 1229 Date: 03/12/19

APPENDIX C

UCOP Seismic Safety Policy Falling Hazards Assessment Summary

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CAAN ID: 1229 Date: 03/12/19

APPENDIX D

ASCE 41-17 Quick Check Calculations

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