1994+Northridge

toc = = Sean Hunt William Saffron Starky Acevedo Andrew Felix

=Introduction= 4:31 am January 17, 1994 the community of Northridge was hit with a devastating earthquake. The earthquake was recorded to have a magnitude of 6.7 and a ground acceleration that was said to be one of the highest in North America. In simple words this was a very powerful earthquake. It caused over 9000 injuries with 72 deaths (Northridge 2010). On the financial side, the earthquake generated over $20 billion in damage, one of the most expensive natural disasters in U.S history. On top of the cost of this disaster, buildings had to be rebuilt. Many campus buildings belonging to the California State University were heavily damaged and one parking structure collapsed. Hospitals were among the most affected buildings. Eleven hospitals were left unusable. As a result the neighboring hospitals had to take care of extra patients. As a result on January 1, 2005 all California hospitals were required to have emergency rooms that were earthquake proof structures. Figure 1 is an image of the destructive power of this earthquake. A [|video of the destruction from the earthquake] can be viewed from this link. == =Keywords\= Northridge, earthquake, collapse, California State University, concrete, steel = = =Causes of Failure= The earthquake involved a blind thrust fault, which is a “shallow-dipping reverse fault which terminates before it reaches the surface”. Figure 2 shows the different fault types. The Northridge occurrence caused many collapses as well as other damages around the city. These damages affected a vast number of structures in the area, including a CSUN parking deck. This 2500 car structure collapsed due to a possible failure in design; it is believed that the cause was “column or beam connection failures.” The failure caused a chain reaction of collapses and movements in the structure. The collapse of interior columns severely crippled girder and floor support. This caused the post-tensioned slab to pull inward, away from the exterior framework. As a result, the exterior framework was also pulled inward, producing a curve in the exterior frame. This failure produced disbelief in mixing ductile and non-ductile systems(Design 1998).

As far as other buildings in Northridge are concerned, the blame is placed on building codes mostly. After the earthquake, several surveys were taken to learn from the damages. These surveys showed that in several of the buildings studied, the estimated response spectrum was almost twice the amount considered sufficient in current codes(Design 1998). To give some perspective, the most heavily damaged buildings were already operating at 2 to 3 times their capacities. The reason for these excessive, but apparently not sufficient, strengths is thought to be the use of large members to satisfy “stringent code drift requirements”. In conclusion, while this occurrence must be classified as a failure, it is a stretch to label it a structural failure because most structures exceeded code requirements. This was a failure of engineering; the building codes for this area, where earthquakes are rather common, were miscalculated.

=Possible Prevention= There were many buildings severely damaged by the Northridge earthquake in 1994. Arguably the most severely affected areas during the earthquake and its aftershocks were the freeways, the hospitals, and the California State University parking structure. Earthquakes always negatively effect transportation; moreover, the freeways and major thoroughfares were closed because of structural failures or collapse. The state of California has taken many precautions to prevent the failure of major highways that could be used for evacuation. Prior to the 1994 Northridge earthquake the Seismic Retrofitting for freeways allowed for too much lateral motion( Design 1998); this resulted in the collapse of the freeway. Better bracing that would require more force to shift the members and more efficient cost effective bracing on the highways would be important and somewhat necessary because of the frequency of earthquakes and the volume of traffic.

Hospitals were severely effected by the Northridge earthquake as seen in Figure 3; this is disastrous to people who are hurt during the earthquake and the patients who are already hospitalized. The failures in the hospitals were directed towards efficient evacuation( Northridge 1995). Hospitals are designed to not collapse from earthquake forces but they are not meant for prolonged use after an earthquake. Steps taken to prevent inefficiency when evacuating such buildings could be having access to generators for the patients in urgent care to use and keeping the patients who need the most assistance with evacuation during a disaster on floors closest to the ground for easier quicker access.

The most significant failure that occurred during the Northridge earthquake was the collapse of the parking structure at California state university. The most glaring aspect of the failure that could have been prevented was making the design conform to code. Codes like that are designed for a reason and are meant to protect innocent people as much as humanly possible from natural disasters(Giovanna 1999). Ignoring Code specifications was a grave mistake made by Dames and Moore Inc. (SCEDC 2010). Using non-ductile, or rigid non-moving members and not offsetting them adequately with ductile members is irresponsible because the structure was located in an area frequented by earthquakes. Making any structure with the most flexibility to lateral forces seems to be the most logical design aspect to focus on in an area like Northridge, California.

= **Lessons from this Failure** = = = Lessons learned from 1994 Northridge earthquake range from changing laws and building codes to initiating long term research and programs to anticipate future events. The United States Geological Survey (USGS) is a scientific agency of the United States government that studies the landscape of the United States, it’s natural resources, and anything that threatens it. The USGS played a major role in the recovery to the earthquake at Northridge in 1994. It is their job to provide earthquake related information as quickly as possible to emergency agencies, emergency response organizations, and all others that are influenced by earthquakes. As a result of the earthquake the USGS has improved seismic recordings in South Carolina and furthered the development of the system in charge of transmitting data(Schiff 1995). This program has specific goals that include recording and distributing earthquake data as soon as the earthquake is detected. By doing this scientist can estimate the extent of the earthquake damage. Knowing the amount of damage an earthquake can do can help us prepare for it and save as many lives as possible. Other goals involve making sure that the seismic networks remain functional under certain conditions. Developing an information transmission program that can be used as early warnings is also one of the important development that happened after the 1994 Northridge earthquake and it is part of the USGS goal list. The NERTP agreement gave the instrumentation program startup funding.

Every aspect of monitoring and predicting earthquakes was improved as a result of the Northridge earthquake in 1994. Agencies are installing a network of GPS systems instruments throughout South California. South California Integrated GPS networks was the name given to the network. They are there to provide rapid, continuous measurements of ground deformation.

As of April 1996, 38 stations were established and are all providing helpful information(SECDC 2010). As a way of reaching out to the public the USGS distributed a handbook to the people of Southern California. By helping people understand what they are faced with it helps them prepare for it.

=Bibliography=

Jenny Yu and Jackie Abrams, (September 16, 1997),** **“Fatal and hospitalized injuries resulting from the 1994 Northridge earthquake”**[| http://ije.oxfordjournals.org/cgi/content/abstract/27/3/459], International Journal of Epidemiology 459(6) This journal article documents the injuries that took place during the earthquake an aftershocks at Northridge. The articles detail the places and types of injuries giving the reader the impression of the human damage the earthquake did.
 * Corinne Peek-Asa, Jess F Kraus, Linda B Bourque, Dushyanthi Vimalachandra,

This paper gives explanation on both fracture locations and failure modes on the connections of structures in Northridge. These explanations are presented with studies of pre – Northridge and post – Northridge earthquake welded beam to column connections used in Northridge. It goes into great detail of forces and stress to show how minor mistakes can result in weak beams leading to a none earthquake proof structure.
 * “Design of steel MRF connections before and after 1994 Northridge earthquake”. Engineering structure Vol.20, No12. California, Elsevier Science, 1998**[| http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V2Y-3TGP4G4-D&_user=209810&_coverDate=12%2F31%2F1998&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1324289917&_rerunOrigin=google&_acct=C000014439&_version=1&_urlVersion=0&_userid=209810&md5=352765fd05535f64d1ff2e47ac0ae6a9]

**Donovan, Luke. "California State University, Northridge Parking Structure C Collapse." //Wikispaces//. 2009. Penn State. 02 February 2010 .** Annotation: Talks about the fatalities occuring during the earthquake. Discusses in detail the design and construction of a parking garage located in Northridge. Later discusses the reasons why the parking garage collapsed, how it collapsed, and the what was changed technically to structural element codes.

This journal article talks about the the equivalent-linear analysis of the earthquake and aftershocks of Northridge. This article documents how the earthquake affected the structure and area of Northridge besides the obvious movment of the earths plates.
 * Giovanna Cultrera, David M. Boore, William B. Joyner and Christopher M. Dietel (October 1999)** **“Nonlinear soil response in the vicinity of the Van Normal Complex following the 1994 Northridge, California, earthquake”,**[|http://docs.google.com/viewer?a=v&q=cache:pA7f8r5is1cJ:quake.usgs.gov/~boore/pubs_online/1999bssa_cultrera_etal_nonlinear.pdf+Nonlinear+soil+response+in+the+vicinity+of+the+Van+Normal+Complex+following+the+1994+Northridge,+California,+earthquake&hl=en&gl=us&pid=bl&srcid=ADGEESjPJD5u3DWzmQ83BA7_m7LgC0FnZJh3iiGa0wFefat50eZUkJ6dguNJXW9tv9yUyKQ7GCqGECSWMR62zGP8EaIQH9mJtDwgVomDVK4nsjsgzMU4TsfL70hEtXGqmQ2rHcbz1abG&sig=AHIEtbTB3DjrrW20BGQzyyZ7PBxMhJTY0Q] Bulletin of the Seismological Society of America 1214 (17)

**Mahin** **Stephen. "Lessons From Steel Building Damaged." //nisee//. 09 December 1997. University of California. 09 Feb 2010 .** Annotation: This source talks about how the earthquake in Northridge affected the steel frame buildings. Also it mentions deailed analyses of damaged buildings. Finally it talks about programs to reduce earthquake hazards in steel moment frame strutures. This source provides information about the site of the failure as well as facts about the actual occurrence. Rather than focusing on the type of failure, this article looks at the damage to the area and its surroundings. It also gives a picture of the damage.
 * "Northridge Earthquake." Web. 10 Feb. 2010. .**

This site gives the reader access about the background information as the others do, but it also provides links with access to extensive amounts of information concerning the aftermath of this failure; they explain the lessons learned and include research published on the subject.
 * "Northridge Earthquake." //Earthquake Engineering Research Center (EERC): University of California, Berkeley//. Web. 10 Feb. 2010. .**

This site provides specific details about the failure, including an animation of the “type of faulting” (blind thrust). It also provides several links to other pages that give the reader access to lots of information about the event.
 * "SCEDC | Northridge Earthquake (1994)." //Southern California Earthquake Data Center Home//. Web. 10 Feb. 2010. .**


 * Schiff Anshel. “Northridge Earthquake: lifeline performance and post-Earthquake response”. United States of America, American society of Civil Engineering, 1995.** [] Describes the recovery responses of the lifelines in Northridge California after the earthquake. It talks about communication, electricity, transportation, hospitals, schools, fire departments and more. The book goes into great detail to see how hospitals and fire departments dealt with the earthquake. It also takes us through the recovery process taken to restore the society in Northridge.