Presented by

Vishva R. Patel

(12CLD044)

contant Introduction

Location Map

Commercial facilities and library atNorthridge Mall

Stores at Northridge Fashion Mall

Holy Cross Medical Centre

Sylmar substation

Rinaldi substation

Code provisions

Conclusions

Introduction Following the magnitude 6.6 Northridge earthquake,

which occurred at 4:31 a.m. on January 17, 1994, groupsof Canadian engineers visited the damaged areas toassist with damage assessment and for general damagereconnaissance.

This paper presents the observations of nonstructural damage to facilities in the Northridge area caused by theearthquake.

Location Map The locations of the facilities discussed in this paper are shown

on a map of the Northridge area in map. Location Key A - Anheuser-Busch Breweries F - Northridge Fashion Mall H - Holy Cross Medical Centre M- North ridge Mall

(Reseda & Nordhoff) N - Northridge Campus R - Rinaldi Substation S - Sylmar Substation V - Veteran’s Administration

Hospital

Commercial facilities and library atNorthridge Mall The mall is 3 km from the epicenter and experienced a

horizontal ground acceleration of 0.8g and a verticalacceleration of 0.5g.

The Northridge branch of the Los Angeles PublicLibrary is a single storey building with masonry wallsand timber roof.

The only observed structural damage was local to acanopy on the east side of the building.

Ceiling damage was extensive with failure of lighting,diffusers, and suspended ceiling system. (fig-A)

(Fig-A) Ceiling damage and contents of shelves scattered at Northridge Branch library.

Stores at Northridge Fashion Mall The mall is 5 km from the epicenter and experienced a

horizontal ground acceleration of approximately 0.6g and avertical acceleration of approximately 0.5g.

The parking structure failures and other structural failuresin this shopping mall have been widely reported.

However, several single-storey structures survived theearthquake with little or no structural damage.

In these buildings nonstructural damage was extensive. The damage was predominantly associated with ceiling

systems. In some cases damage to shelving and racking was

observed.

Holy Cross Medical Centre The Holy Cross Medical Centre, located in the Mission

Hills district, is approximately 8 km from the epicenterand experienced a horizontal ground acceleration ofapproximately 1.0g and a vertical ground accelerationof approximately 0.5g.

lt is a two-storey reinforced concrete structure with alarge light steel framed mechanical penthouse situatedon its roof.

Sylmar substation The Sylmar substation is 13 km from the epicenter and

experienced a horizontal ground acceleration ofapproximately 0.8g and a vertical ground accelerationof approximately 0.5g.

The thyristor valves suspended from the roof of thevalve building sustained only minor damage one of thesuspension insulators between valve groups failed (Fig.23).

(Fig - B)Sylmar east - thyristor valves sustained only minor damage during earthquake.

(Fig - C) Sylmar east - failed 500 kV surge arrester

Rinaldi substation The Rinaldi substation is 8 km from the epicenter and

experienced a horizontal ground acceleration of approximately 0.85g and a vertical ground acceleration of approximately 0.5g.

Failure of the nearby Los Angeles Aqueduct flooded the control building and locally deposited materials in the Rinaldi switch yard, but'did not appear to have significantly affected the operability of the yard.

Damage to this 500/230 kV substation during the earthquake was reported as being extensive.

Code provisions The majority of nonstructural damage occurred to

components that had inadequate restraint provisions.

It was observed that the majority of components withrestraints designed to current code requirements (i.e.,0.4g peak horizontal acceleration for UBC zone 4)performed well, in spite of measured groundaccelerations of twice the design value.

In the several situations where damage did occur tocomponents in facilities designed to current codeprovisions, the failure can be attributed to poor designdetails.

Conclusions Observations made following the Northridge

earthquake show the significance of nonstructural damage in buildings and facilities where there is little or no structural damage.

The lessons of this earthquake show the high potential for loss of life, personal injury, and considerable economic cost due to nonstructural damage.