Day 4 Report on Chile Earthquake – Talca and Concepcion, Chile
Talca, Chile
photos by James Liu
We apparently ended up in a hostel….yes a hostel by the name “Casa Chueca” which in Spanish means “Crooked House”. There may have been a little miscommunication from the tour guide (“hotel” I guess sounds close to “hostel”). Apparently, there were not too many places available for stay. The amenities were adequate and the owners/staff were very warm and friendly. We made it through the night in the adobe structures, got up at 7am and began our trek to see another hospital building we heard that was damaged severely.
Bldg ID 3-10.1 Talca Regional Hospital (35⁰ 25′ 35″, 71⁰ 38′ 47″)
Not unlike our medical centers, the hospital we visited was a collection of various buildings of different vintages. Some of the hospital functions were relocated to the adjacent medical clinic. Roger and David once again convinced the medical director to allow access for us to observe the damage. The damage observed was severe, but did not appear as bad as the hospital we observed yesterday in Curico.
1937 and 1950 Building
The oldest structure (started as a 40 bed hospital) was 4 stories, rectangular in shape with a concrete frame and infill hollow brick. There was a pitched roof supported by steel trusses. Concrete slabs supported by concrete beams were typical floor systems for the lower levels. The roof diaphragm did not appear to be connected to the transverse walls. The worst damage occurred at the 3rd story where the masonry partitions were falling into patient rooms. There was no out-of-plane support at the top of the walls. Surprisingly, there was little or no structural damage at the lower stories. Throughout the hospital, heavy lath and plaster ceilings fell from the ceiling and created hazards to walk through. Electricity was out. The OR’s were on the upper floors…exam lights and gas columns performed relatively well. These two structures were planned for demolition to make room for a replacement hospital, but the earthquake helped accelerate the schedule.
1990 structure (620 bed hospital inclusive of original bldgs)
The newest hospital structure, a 4-story concrete shear wall building was rectangular in shape with a lightwell in the middle. From our observation, it appeared to have sustained very minor superficial damage. However, there was a small portion of the hospital that suffered damage and was not in use. There were two seismic joints in the structure with MEP lines designed to accommodate movement at the joints. The lights were all anchored with vertical safety wires. However, we noted a large pile of lights sitting on the corner of the stair. It appeared that some of the support wires broke. Ceiling tiles were down, but the ceiling tile support systems were braced with wires, but no compression struts could be seen.
Clinic
The Clinic was a steel structure, 3-story in height with a steel braced frame lateral system. Quite a number of brace connections showed signs of distress. Gusset plates warped, bolts slipped. Some of the tube steel braces bowed out of plane, but no buckling occurred. The brace frames discontinued at the upper floor suggesting a cantilevered column lateral system. The floors are constructed of concrete slab over metal deck. The roof appeared to be OSB over light gage steel framing. In addition, horizontal X bracing was observed at the roof diaphragm.
In general, the older portion of the hospital performed well. The behavior would be categorized as what the expected performance of an SPC 2 hospital building. Irreparable damage, but life preserved. No patient was killed during the earthquake. The newer structure definitely fit the immediate occupancy characteristics, with exception of the one area that was damaged.
Other Buildings
In addition to the hospital, we noted some silos that had damage. Many roads had been damaged.
Concepcion
On the way to Concepcion, our van ran into technical difficulties. The engine overheated and we pulled over. James and David were trying to be mechanics, but no luck. The drivers flagged down a passing bus from the same tour company and we were on our way again.
We made to Concepcion around 2:15pm. After lunch at 3pm, we began our trek to observe the apartment building that received the most media attention. Walking around the site, we met the 3-star general appointed by the Chile president to investigate the building collapse as well as maintaining the curfew in the city. We continued investigating neighboring buildings that actually performed quite well from the earthquake. Since a military curfew was in place, we returned to our hotel at 8:00pm (our hotel only has water for 1 hour between 7:30pm to 8:30pm).
Bldg ID 3-10.2
Alto Rio Bldg (36⁰ 49′ 41″, 73⁰ 03′ 41″)
This concrete apartment building built in 2009 (currently not shown on Google Earth) has been strewn across all media channels. When we arrived, we were shocked and in awe of the devastating force this earthquake produced. Survivors were giving testimonials of their earthquake and survival experience. Our tour guide was very sad and on the verge of tears after seeing the site in person. The 16-story structure, with 2 levels below for parking housed approximately 80 tenants. There were approximately 8 fatalities. The search and rescue effort ended yesterday with the last victim found. The lateral system consisted of shear walls in both directions. It is not immediately clear how the building failed due to significant search and rescue efforts that may have increased the amount of damage to the structure (holes cut into slabs, adjacent soil excavated, various elements leaning on the wall, etc.). It appears that the building failed in shear at the base. The structure toppled over and broke in half and went through the basement slab of the adjacent building site (the foundations and 1st floor slab were completed for another apartment building of the same design on the adjacent site). We observed the 8″ thick shearwalls had #3 bars at 8″o.c. with 4 #7 boundary bars typically. A neighboring building of similar construction was still standing. Click here to view video footage of the site.
Bldg ID 3-10.3
Metro Control Station (36⁰ 49′ 47″, 73⁰ 03′ 37″)
This structure was located southeast from the Alta Rio Bldg, approximately 1 block away. Unlike the Alta Rio, the structure performed very well for this earthquake. The building function is to provide support for all metro transportation routes. This station was very interesting with multiple types of construction. The overall exterior “shell” consisted of steel roof trusses supported by steel brace frames. Underneath the “shell”, the structure consisted of a two-way concrete frame system with columns extending up and to provide gravity support for the trusses. A third steel brace frame structure is interconnected, but seismically separated, to the concrete portion and also extends up to support the overhead trusses in the “shell”. This building did not have an observable structural damage. There was a lot of nonstructural ceiling damage that was typical on all floors. The data control equipment, the critical element for operation of the metro, was damaged from the shaking. This building is shut down and currently not in operation. As a result, the metro system is still down. They plan to be back up and running in April. Coincidentally, the last victim in the Alta Rio bldg actually worked in this building.
Bldg ID 3-10.4
Ministry of Public Works Bldg (36⁰ 49′ 47″, 73⁰ 03′ 37″)
Two buildings down, we found another very interesting structure. From a distance, the structure was very prominent and definitely caught our attention. The building was approximately 6-stories tall with brace frames and bolted moment frames at the lower level. The brace frames only occurred at exposed lower levels and the bolted moment frame continued as the lateral system for the remainder of the structure. There is a basement where the brace frames and moment frames continue down into. Between the two buildings, a seismically isolated steel frame structure exists providing the interconnection and access to the all floors (stairs and elevators). We met the chief of public works who gave us a tour of the entire building. He gave us an overview of how they design and construct public buildings, which also includes school structures. The building performed very well with very minor damage (ceiling tiles falling, partition walls leaning, pounding between the structures).
We are now staying at the Holiday Inn in Concepcion. We will be here for a number of days and continue our reconnaissance. Until the next blog….
