reconnaissance report of chilean industrial facilities ...€¦ · reconnaissance report of chilean...

Reconnaissance Report of ChileanIndustrial Facilities Affected by the 2010Chile Offshore Bío-Bío Earthquake

Farzin Zareian,a) M.EERI, Carlos Aguirre,b) Juan Felipe Beltrán,c)

Ernesto Cruz,d) M.EERI, Ricardo Herrera,e) Roberto Leon,f ) M.EERI,Arturo Millan,g) and Alejandro Verdugoh)

This paper summarizes findings of an EERI reconnaissance team and a groupof Chilean experts on damage to industrial facilities caused by the 27 February2010 Offshore Bío-Bío Earthquake and ensuing tsunami. Chile’s industry as awhole was severely affected when major industrial plants such as paper mills,wood mills, thermoelectric power plants, and oil and gas refineries were shutdown following the earthquake either in response to the damage sustained orto maintain structural and environmental safety. Damage resulted primarilyfrom ground shaking; however, it was exacerbated by the ensuing tsunami incoastal areas. Important industrial sectors, such as the wine industry and fishing,pulp and paper industries, suffered severely. Observed damage was primarily dueto inadequate anchorage of equipment, differential movements between adjacentsupports of piping and equipment, foundation displacements, and failure of non-structural elements and equipment. [DOI: 10.1193/1.4000049]

INTRODUCTION

The offshore Bío-Bío earthquake with magnitude of Mw ¼ 8.8 struck Chile on27 February 2010 at 3:34 a.m. local time. The subduction earthquake occurred at the inter-face of the Nazca and South American Plates (epicenter 35.909˚S, 72.733˚W) at a focaldepth of 35 km and had a north-south extension of 450 km. The epicentral distance toChile’s second-largest city, Concepción, was 105 km. The earthquake affected an areaof approximately 160,000 km2, which houses approximately 75% of the population ofChile, damaging 370,000 homes, affecting 1.8 million people, and claiming approximately500 lives (USAID 2010). From Figure 1, which shows a schematic of the distribution of

Earthquake Spectra, Volume 28, No. S1, pages S513–S532, June 2012; © 2012, Earthquake Engineering Research Institute

a) University of California - Irvine, E/4141 Engineering Gateway, Irvine, CA 92697b) Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso, Chilec) Universidad de Chile - Oficina 440 Departamento de Ingeniería Civil, Santiago, Chiled) Pontificia Universidad Catolica de Chile - Vicuña Mackenna 4860, Macul (Correo 22), Santiago, Chilee) Universidad de Chile - Oficina 435 Departamento de Ingeniería Civil, Santiago, Chilef) Virginia Tech, 102-D Patton Hall, Blacksburg, VA 24061g) Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso, Chileh) BECHTEL CHILE LTDA, Chile

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Figure 1. Map of economic activity in Chile (after Mapcruzin.com 2011).

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industrial activity in Chile, the high concentration of industries in the area affected by theearthquake is evident. The hardest hit areas ran from Temuco in the south to Santiago inthe north.

Chile’s economy is structured around three major sectors: industry, services, and agri-culture. Important industries in Chile include mining, mostly north of Santiago, and pulp andpaper, fish processing and wood in the regions south of Santiago. Chile is mass producer ofwheat, grapes, fruits, and fish, with most of the agricultural products grown in the centralvalley that runs from Santiago to Temuco. Figure 2 shows Chile’s Economic Profile accord-ing to Economy Watch (2010). Chile’s exports account for 40% of its GDP and have experi-enced growth of 4% since 1999.

Chile’s industry as a whole was severely affected, primarily because major industrialunits such as: paper and wood mills, thermoelectric power plants, and oil and gas refinerieswere shut down after the earthquake. Other important industries suffered damage as well,either due to the effects of the earthquake ground shaking (wine industry) or a combination ofground shaking and ensuing tsunami (fishing and pulp and paper industries). Mining opera-tions in the area north of Santiago were halted immediately after the earthquake to ensure thatequipment was not damaged.

The observed damage is similar to that reported after the large earthquakes of 1960 bySteinbrugge and Flores (1963), and was mainly due to inadequate anchorage of equipment,

Figure 2. Summary of Chilean economy (Economy Watch 2010).

RECONNAISSANCE REPORTOF CHILEAN INDUSTRIAL FACILITIES S515

differential movement between adjacent supports of piping and equipment, and foundationmovement. While there was evidence of significant inelastic demands in older non-building structures, new properly engineered structures showed little evidence of signifi-cant inelastic demand on structural members. For older structures there were a few isolatedcollapses and none for newer structures. Fortunately, there was no loss of life associatedwith these limited failures. On the other hand, damage to equipment was extensive due tofailures of inadequate anchorage and bracing. After a brief review of seismic design guide-lines for industrial facilities in Chile, selected observations of damage to certain typesof industrial facilities are presented and discussed. Wineries are only peripherallyaddressed in this paper as they are the subject of a separate contribution to this issue(Zareian et al. 2012).

DESIGN CONSIDERATIONS FOR INDUSTRIAL FACILITIES IN CHILE

The seismic design of industrial facilities is governed by the Chilean codeNCh2369.Of2003 (INN 2003). This specification establishes two performance levels,Life Safety and Continuity of Operations, for the most severe earthquake expected in aregion. More specifically, the objectives are as follows: to avoid collapse of structures;to avoid fires, explosions, or emissions of toxic gasses and liquids; to protect the environ-ment; to ensure operation of escape ways during the earthquake emergency; to keep essentialprocesses and services running; to avoid or minimize downtimes; and facilitate inspectionand repairs of damaged elements. The Chilean code divides Chile into three seismic regions(see Figure 3), where the earthquake hazard decreases from the Pacific coast to the Andesmountains. The seismic demand is characterized by a design acceleration value or a seismiccoefficient according to the seismic region, which is modified considering the soil conditionsand the inherent equivalent viscous damping, deformation capacity, and overstrength of thestructure.

At the time of the earthquake, the design of the majority of the existing reinforcedconcrete structures was governed by ACI 318-99 (ACI 1999), considering the threeseismic zones as high seismic hazard zones in the application of Chapter 21 of thiscode. In the case of steel structures, given the lack of an official national design code,NCh2369.Of2003 contains design considerations largely based on the AISC LRFDSpecification (AISC 1999) and the AISC Seismic Provisions (AISC 2002), complementedwith recommendations based on the experience of reputed Chilean structural designoffices. The application of NCh2369 results on structures with limited ductility butsignificant overstrength, which explains why for this extreme event, the observation ofdamage to structural components shows that most of the industrial structures seem tohave remained nearly elastic.

Figure 4 shows the response spectra of the horizontal components of ground accelera-tion, for 2% equivalent damping ratio, recorded at five sites shown in Figure 3 within theaffected area, namely: Hualañé, Curicó, Constitución, Talca, and Concepción. These spectraare compared to the design spectrum established in NCh2369 (INN 2003), considering no

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modification of the response (R ¼ 1), the same equivalent damping ratio, and soil type III.It can be seen that, with only exception of the record from Concepción, the recorded groundmotion response spectra for periods larger than one second are comparable to the designlevel earthquake considered by NCh2369; therefore, continuity of operation should beexpected for industrial structures in this area. The particular shape of the record from Con-cepción is related to the unfavorable soil conditions in this city, which sits on fluvial depos-its part of the Bío-Bío river delta. This record is particularly damaging for flexiblestructures, imposing a non-decreasing displacement demand for structures with longernatural periods.

Figure 3. Area affected by the Offshore Bío-Bío earthquake and location of recording stations(after Boroschek et al 2010).


OBSERVED DAMAGES TO THE INDUSTRY SECTORS IN CHILE

Several reconnaissance teams investigated industrial facilities from Coronel (south ofConcepción) up to Santiago (the capital of Chile) within two weeks after the earthquake,following reports of substantial structural and nonstructural damage to selected facilities.At that time, gaining access to the damaged facilities was time consuming and difficultas many of the facilities were still being evaluated both for structural and environmentalsafety. In addition, many industrial facilities elected not to share information for busi-ness-related reasons. However, reconnaissance teams were able to observe a few industrialplants and observe patterns in the damage suffered by the industry. Despite the lack of infor-mation from plant owners, an estimate of earthquake effects on industrial facilities can bededuced from the power consumption statistics. One month after the quake, 15 main indus-trial plants had reduced their power demand to just 13% of normal (Raineri, 2010). Powerdemand evolution for the first three months of 2009 and 2010 is shown in Figure 5.

POWER PLANTS

Historically, Chile has relied heavily on hydroelectric power, but the country’s rapidgrowth since the late 1990s has forced the construction of new thermoelectric plants fueledby diesel, coal, and natural gas (in part as LNG). As much of the latter fuels are imported bysea, a number of these large projects are located in areas where deep water ports and terminalscan be built. The reconnaissance team visited one such facility, a 350 MW pulverized coalfired cycle power plant under construction in Coronel, about 20 miles south of Concepción.

Figure 4. Response spectra of recorded ground motions and design spectrum fromNCh2369.Of2003, for 2% equivalent viscous damping and Soil Type III.

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At the time of the earthquake, construction was estimated at 50% to 60% of completion(Figure 6a). The team explored the entire site, from the water intakes and outfalls (Figure 6b),about a mile east of the main site, to the steam turbine and generator building andthe transformers bays. Overall, damage was relatively minor. Damage occurred due to(1) construction scheduling, the structure/equipment was inadequately braced (Figure 6c);(2) excessive settlement occurred in foundations or structures not supported by piles(Figure 6d); (3) equipment was undergoing alignment prior to final installation of anchoringsystems (Figure 6e); and (4) nonstructural elements were not seismically detailed in officeareas (Figure 6f). The only extensive damage was to a large gantry used in the coal handling /storage area. Another thermoelectric plant nearby, which was built in the 60s, suffered moreserious damage and the electricity supply was decreased as a result, however, power outageswere due to failures in the distribution system, mainly in the substations. The hourly load onthe main electrical system in the central and southern regions increased from a range of4500MW to 6200 MW in the days before the earthquake to a complete blackout immediatelyafter the event; this was followed by a steady increase to about 3000 MW two days after theevent. Only about 6% of the installed capacity was destroyed by the earthquake but the dis-tribution system was severely damaged (Araneda et al. 2010).

PORT FACILITIES

The reconnaissance team visited the port of Coronel. The port was undamaged with rela-tively minor subsidence on wharves (Figure 7a). Cranes located on the unique base isolatedwharf where undamaged (Figures 7b, c, and d). The port at Huachipato suffered the failure inshear of all the inclined piles, presumably due to insufficient embedment of the steel tube in

Figure 5. Maximum daily power demand comparison (adapted from Raineri 2010).


the concrete slab (Figure 7e). Derailment of cranes without seismic restrainers was caused bythe strong shaking, and damage to a crane with seismic restrainers (Figure 7f) was inducedwhen the hook of the crane was pulled by a ship trying to reach deeper waters to avoid thetsunami. Damage to smaller ports was more serious due to the tsunami, which displacedcontainers, damaged fishing installations and cold storage facilities essential for the exportof agricultural and fishing products.

Figure 6. Damage to the 350 MW coal fired power plant power plant (under construction).

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PULP AND PAPER PLANTS

The team visited two pulp and paper plants (located in the rupture area). Both of theseproperties are subject to confidentiality and thus no pictures are provided. In general, therewas no significant damage to structures. Most of failures were in steel structures older than

Figure 7. Damage to port facilities.


20 years having no ductile detailing. Typical damage included buckling of slender bracingand fracture of gussets in bracing connections (where design was not based on tension capa-city of bracing). Permanent drift in a couple of steel buildings resulted from buckling of thesole diagonal member in the braced frame (lack of redundancy). A large number of anchorbolts yielded and fractured in columns and equipment bases; in addition, numerous instancesof crushing of grout under base plates and compression failure of concrete piers wereobserved probably due to low quality of grouting and poor rebar detailing.

On the other hand, most of buildings and structures designed using modern codes, such asNCh2369 Chilean code, did not sustain any damage. Structural damage was observed inboiler steel buildings of power plants (each pulp plant has its own power plant). Failureswere concentrated in seismic stoppers, which in some cases led to total destruction ofthe restraining elements and the consequent clashing between boiler and building structure.

Cracking of a concrete tank was observed in the effluent treatment system of one of thevisited plants. The cracking was locally concentrated in opposite sides of the tank, probablyassociated with a directionality of seismic sloshing.

In one case, a plant was inundated by the tsunami; damage was confined mainly to minorbuildings (offices and small warehouses) located in the flooded area and resulted in totaldestruction of quite a few. Heavy industrial structures were not damaged by the tsunami.

CEMENT PLANTS

The team visited a very large cement factory in the Bío-Bío region, about 100 km fromthe epicenter; at the time of the earthquake, a large part of the plant was down for repairs andupgrades. Damage was limited to hairline shear and torsional cracks in the largest silos(Figure 8a), some buckled X-braces in the top story of the plant (Figure 8b) and some move-ment in the equipment. In general, the plant performed well and was back in productionshortly afterwards. This was important - as the reconstruction efforts would probablyhave been affected by lack of this basic construction material.

Figure 8. Damage to cement factory.

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STEEL PLANTS

Severe localized damage was evident at the only steel plant visited in Huachipato, nearConcepción. Figure 9 shows several performance problems, including failure of conveyorbelt support structure (Figure 9a), large settlement (about 40 cm.) of an interior column(Figure 9b), fractured braces (Figures 9c and 9d), buckling of downspout tubes (Figure 9e),

Figure 9. Damage to steel plant.


and elongated and broken bolts in the support structure for a large chimney (Figure 9f). Thiswas one of the more severely damaged facilities visited by the team, but performance must beconsidered to be within the expected range as the facility is of the older construction, islocated close to the epicenter, and is quite extensive.

WAREHOUSES

Observed damage to warehouses was predominantly of two types. The first type affectedwarehouses with precast walls, such as the structures in Concepción (Figure 10a), alongRoute 5 which connects Santiago to Concepción (Figure 10b), and in the Santiago suburbs(Figure 10c). Poor detailing of connections between precast elements and roof diaphragmfailures resulted in structure collapse in many cases. The other common type of failurewas the collapse of pallet racks due to inadequate anchorage and bracing (in many casesthese were nonexistent) or, even when the racks performed well, the loss of contentsfrom shelves (Figure 10d).

Figure 10. Damage to warehouses.

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A considerable amount of damage to stacked and binned goods was observed, includingplastic beverage containers (Figure 11a), construction materials (Figure 11b), agriculturalproducts (Figure 11c), and granular materials (Figure 11d).

FISH PROCESSING PLANTS

Most of the processing facilities, located at the seaside in Talcahuano Port Bay a fewmiles to the north of Concepción, were destroyed. The severe damage was mainly due tothe tsunami and extended to ship loading structures, process plants and cold-storing facilities.As shown in Figure 12, typical construction consists of light steel buildings.

TANKS AND SILOS

The reconnaissance team was able to obtain pictures of buckled refinery steel tanks andcooling towers in refineries around San Vicente and Hualpén (Figures 13a and 13b), nearConcepción. These were taken from a distance and it appeared that the plants were not inoperation. The team observed a number of damaged steel and concrete tanks along route 5(Figures 13c, 13d) and in the city of Talca (Figures 13e, 13f).

Figure 11. Damage to stacked goods.


WINERIES

The wine industry in Chile is heavily dependent on the use of stainless steel tanks.Although a small percentage of wine is processed in reinforced concrete tanks, most ofthese tanks sustained almost no damage and the loss of wine associated to the failureson this type of tanks was minimal. Typical damage observed to reinforced concretetanks consisted of horizontal cracks associated with cold joints executed during the tankconstruction and a rare case of diagonal cracks, associated with insufficient transverse rein-forcement of the tank wall.

Losses were mostly due to damage to stainless steel fermentation tanks, collapse ofstacked storage, and loss of unprocessed wine due to spills. Two types of steel tankswere found in wineries during the inspections: leg-supported and continuously supportedtanks. Leg-supported tanks are commonly used to ferment up to 50,000 liters. Two mainfailure modes were observed in this type of tank: buckling of the tank legs due to insuffi-cient thickness of the leg plate and denting of the tank wall due to an inappropriate leg /mantle relative stiffness leading to an undesirable “strong leg-weak mantle” mechanism(Figure 14). In both cases, tank legs are directly welded to the tank wall without usinga stiffener ring.

Continuously supported tanks typically were found to have capacities greater than 50,000liters. The observed damage to this type of tanks can be classified as follows: instability of thetank wall, failure of the anchoring system, failure of welding connection between tank walland bottom plate, and failure of connections between piping and tank wall. Two modes ofinstability failure of tank walls were observed in the wineries visited: elephant foot bucklingand diamond-shaped buckling. The elephant foot buckling mode was seen in squat tanks(height/diameter < 1) and was characterized by the appearance of a bulge in the tankshell due to its insufficient thickness (Figure 15a). This type of failure was seen justabove the tank base and at wall height where the wall thickness changed. Diamond-shapedbuckling was present in slender tanks (height/diameter > 1) due to stress concentration in

Figure 12. Damage to fish processing plants.

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Figure 13. Damage to tanks and silos.


regions where changes of stiffness occurred abruptly. As shown in Figures 15b, this mode offailure was generally encountered in zones where the tank wall thickness changed abruptlyand where tank wall was connected to an anchorage system.

In some continuously supported tanks anchor bolts were used to prevent the sliding andoverturning of the tanks due to lateral loads. Inspections revealed that this type of anchoragesystem failed due to three main sources: corrosion in anchor bolts, insufficient distance fromthe connection to the edge of the foundation, and deficient effective embedded bolt length.Figure 16a shows a combined failure in which corrosion in anchor bolt, insufficient distancefrom the connection to the edge of the foundation, and diamond shape buckling of the tank

Figure 15. Modes of tanks wall instability: (a) Elephant foot buckling mode, (b) diamond-shaped buckling mode.

Figure 14. Failure in legged stainless steel fermentation tanks: (a) Tank leg buckling, (b) dentedtank wall

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wall is apparent. Some tanks that were not anchored or poorly anchored overturned and sliddue to lateral force and impacted other tanks damaging their roofs and walls as shown inFigures 16b, 16c, and 16d.

Another common mode of failure observed during the inspections of wineries was theimplosion of the tanks due to vacuum as shown in Figure 17. Failure of the connectionbetween piping and tank wall (Figure 17a and 17b) and the rupture at the bottom plateand wall-shell junction (Figure 17c) are two main reasons that we believe induced vacuumleading to implosion of the tanks.

Figure 16. Damage to continuously supported stainless steel fermentation tanks.


Once wine has been bottled, wine bottles are generally stored in wooden, plastic or metal-lic bins. Wooden bins exhibited varying performance during the earthquake depending on thequality of their construction. Poorly constructed wooden bins lost the majority of the storedbottles (Figure 18a). On the other hand, properly constructed wooden and plastic bins per-formed satisfactorily with no loss of stored bottles reported (Figure 18b). Metallic bins exhib-ited very poor performance during the earthquake and often collapsed leading to loss ofproduct (Figure 18c). A separate article on the performance of wineries is provided inthis special issue (Zareian et al. 2012).

Figure 17. Stainless steel fermentation tanks implosion due to vacuum effect.

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SUMMARY OF OBSERVATIONS

The damage to industrial facilities observed in the aftermath of theMw ¼ 8.8 earthquakethat struck Chile on 27 February 2010 can be considered to be minor from the structuralstandpoint. While there was evidence of significant inelastic demands in older non-buildingstructures, new and properly engineered structures showed little evidence of significantinelastic demand on structural members. For older structures there were a few isolated col-lapses and none for newer structures. Fortunately, there was no loss of life associated withthese limited failures. On the other hand, damage to equipment was extensive due to failuresof anchorage and bracing. The losses due to business interruptions were very large, parti-cularly for large plants in the Concepción area, which were out of commission for severalweeks (and in some cases months).

ACKNOWLEDGMENTS

The research was funded by the EERI Learning from Earthquakes project, under grant#CMMI-0758529 from the National Science Foundation (NSF). Any opinions, findings, and

Figure 18. Wine storage damage.


conclusions or recommendations are those of the authors and do not necessarily reflect theviews of NSF. The authors would like to thank Victor Sandoval and César Sepúlveda, grad-uate students at the Pontificia Universidad Catolica de Chile in Santiago, for their assistanceto the reconnaissance team.

REFERENCES

American Concrete Institute (ACI), 1999. Building Code Requirements for Structural Concrete(ACI 318-99), Farmington Hills, MI.

American Institute of Steel Construction (AISC), 1999. LRFD Specification for Structural SteelBuildings, Chicago, IL.

American Institute of Steel Construction (AISC), 2002. Seismic Provisions for Structural SteelBuildings, ANSI/AISC 341-02, Chicago, IL.

Araneda, J. C., Rudnick, H., and Miquel, P., 2010. Lessons from the 2010 Chilean earthquake andits impact on electricity supply, Powercom 2010, Hangzhou, China.

Economy Watch, 2010. Chile Economy, available at http://www.economywatch.com/world_economy/chile/.

Boroschek, R., Soto, P., and Leon, R., 2010. Maule Region Earthquake, 27 February 2010,Mw ¼ 8.8, Renadic Report 10/08, Department of Civil Engineering, University of Chile,Santiago, Chile.

Instituto Nacional de Normalización (INN), 2003. NCh2369.Of2003: Earthquake ResistantDesign of Industrial Structures and Facilities, Santiago, Chile.

Mapcruzin.com, 2011. Chile - Economic Activity from Map No. 500814 1972, available at http://www.mapcruzin.com/free-maps-thematic/chile_econ_1972.jpg.

Raineri, R., 2010. Presentación sobre el estado del sector eléctrico afectado por el terremoto del27 de febrero de 2010 (in Spanish).

Steinbrugge, K. V., and Flores, R., 1963. The Chilean earthquakes of May, 1960: A structuralengineering viewpoint, Bulletin of the Seismological Society of America 53, 225–307

USAID 2010. Chile – Earthquake, Fact Sheet #17, Fiscal Year (FY) 2010, Washington,D.C., available at http://www1.usaid.gov/helpchile/documents/04.08.10-USAID-DCHAChileEarthquakeFactSheet17.pdf.

Zareian, F., Sampere, C., Sandoval, V., McCormick, D., Moehle, J., and Leon, R., 2012. Recon-naissance of the Chilean wine industry affected by the 2010 Chile offshore Maule earthquake,Earthquake Spectra 28, this issue.

(Received 30 March 2011; accepted 19 April 2012)

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http://www.economywatch.com/world_economy/chile/




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