Baja California Earthquake – El Centro LDS Meeting House
Two other engineers from San Diego and I arrived in El Centro Friday morning and consulted the local paper for additional information on the earthquake damage. We discovered an article that mentioned that a church just down the street from where we were had been damaged, and that the steeple was being taken down for safety concerns. We noticed the cranes in the distance, and headed straight to the site, finding a demolition crew in the process of jack hammering and torch-cutting the steeple into segments that could easily be removed via the crane (see below).
The meeting house was built in the mid 1960’s by members of the church who lived in the area, and its design is consistent with other LDS meeting houses built during that time. Specifically, a tall lightly reinforced masonry Chapel and Cultural Hall space are surrounded by smaller and shorter classrooms and offices. A wood roof system with glulam beam girders is used to create the long spans over the Chapel and Cultural Hall areas. The steeple was over 40’ in height and constructed of concrete, masonry, and light reinforcing.
The steeple had shifted and rotated just over 1 inch horizontally just below the roof line, most likely shearing the rebar across the joint (see below). This most likely occurred due to the t-shape section of the steeple contributing to a torsional response, combining with the high stresses at the plane where the steeple tied into the main structure. Besides the damage to the steeple, only very minor cosmetic damage could be observed on the structure from the outside.
Figure 2. Steeple had shifted and rotated approximately 1 inch horizontally
Figure 3. Segment of steeple removed by demolition team showing typical cross section
The church facilities officer in that region escorted us inside of the meetinghouse and showed us the damage to two interior shear walls that separate the chapel space from the cultural hall space. The shear wall damage observed consisted of typical diagonal cross cracking of the masonry walls, some vertical cracking in the walls, and some cracking at the joints of where perpendicular walls intersected the shear walls (see below).
Figure 4. Cross cracking of interior masonry shear wall
Figure 5. Cracking at interior masonry walls
The church building was located approximately two to three blocks from the strong motion sensors which measured 38% g PGA, with 150% g of spectral acceleration at the short periods.
