HomeMy WebLinkAboutAGENDA REPORT 1991 0123 CC REG ITEM 08G VMOORPARK
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PAUL W. LAWRASON JR.MOORPARK, CALIFORNIA QPPK =a� STEVEN KUENY
Mayor City Council Meeting o����2 City Manager
BERNARDO M. PEREZ of �' �j 199� �' CHERYL J. KANE
Mayor Pro Tern. ��� City Attorney
SCOTT MONTGOMERY ACTIO 4 NCO. 4 PATRICK RICHARDS,A.I.C.P.
Councilmember ii `m' Director of
.JOHN E. WOZNIAK �9 Community Development
Councilmember fey � E° Jos-4 JOHN F. KNIPE
LILLIAN KELLERMAN � /f City Engineer
City Clerk JOHN V. GILLESPIE
Chief of Police
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MEMORANDUM RICHARD T. HARE •
City Treasurer
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TO: . The Honorable City Council
FROM: John F. Knipe, City Engine
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DATE: January 16, 1991
SUBJECT: CALTRANS SEISMIC DESIGN CRITERIA
118/23 FREEWAY CONNECTOR PROJECT
BACKGROUND INFORMATION
Following the 1989 Loma Prieta Earthquake in Northern California, City Council requested
additional information concerning the seismic design of the 118/23 Freeway Connector •
project. The information received from Caltrans was forwarded to City Council on
December 13, 1990. In this submittal, Caltrans supplied a copy of their Bridge Design
Specifications for seismic design and the geotechnical report for this project.
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Overall, staff finds the Caltrans information and design methodology acceptable.
DISCUSSION
As requested by City Council, gaff has continued to work with Caltrans to obtain additional
information on the seismic design of the 118/23 Freeway Connector Project since the 1989
earthquake. This information, received' o`rn_ December 10, 1990, was prepared by the
Division of Structures located in the Caltrans'`;Sacramento office.
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Upon receipt, this information was then forwarded to the City Engineer's Structural Division
for review. Their review concludes that the design methodology described is acceptable and
similar to that performed throughout the State in both the public and private sectors.
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799 Moorpark Avenue . Moorpark, California 93021 (805) 529-6864
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As noted in the cover letter, Caltrans employed a computer program called STRUDL
(Structural Design Language)for the seismic analysis of the bridge structure. This program,
developed at MIT, is highly regarded and used extensively in the,.structural design
community. Their use of STRUDL on the 118/23 Connector.Project indicates it received
state-of-the-art analysis.
Further, Caltrans structural design methods have been undergoing considerable review and
critique since the Loma Prieta Earthquake.. As noted by Caltrans, the design method used
for the 118/23 Freeway Project has been affirmed by both the Governor's Board of Inquiry
and independent peer reviews.
The geotechnical report also noted that seismic design of .structures be based on the
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Maximum Credible Earthquake Magnitude 7.5
Maximum Ground Acceleration . 0.6g
For reference, the Loma Prieta Earthquake had a magnitude of 7.1 and a ground
acceleration 'of 0.3g at the I-880. Ground acceleration at this location was magnified two
to three times, however, by a soil condition knows as "soft soil". This soil condition is
normally found in coastal areas and'does not exist at the 118/23 project site. -
Staff has also reviewed Map Sheet No. 45 of the California Division of Mines and Geology.
This map shows anticipated ground acceleration values to be expected with the occurrence
of a Maximum-Credible Earthquake. This map indicates an anticipated 0.6g ground
acceleration in the freeway project area confirming the design criteria used.
RECOMMENDEDACTION • S
Receive and file.
Copy: Steve Kueny, City Manager, 4
Gary Antonucci, Structural''Division., -
JFK:sf \ •
01198/3001
IMO401.COU
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