GOSHEN UNITED METHODIST CHURCH DAMAGE SURVEYby Tim Marshall, March 1994.
1. GENERAL FINDINGS
A tornado struck the Goshen United Methodist Church on Sunday, March 17, 1994 around 11:35am resulting in the collapse of the sanctuary that contained about 150 people. A total of 20 fatalities and about 90 injuries occurred in the sanctuary. At the request of NOAA in Washington DC, I conducted a site visit to determine the cause of the collapse.
My site visit revealed that the tornado centerline passed about 200 yards north of the church. The forward speed of the tornado was about 55mph at the time the church collapsed. The tornado had traveled about 45 miles on the ground before striking the church.
2. SPECIFIC FINDINGS ABOUT THE CONSTRUCTION OF THE SANCTUARY
The sanctuary was rectangular in plan with the long dimension oriented east west. Dimensions were 60 feet long by 38 feet wide. The sanctuary was located in the middle portion of the church building. Classrooms extended to the west of the sanctuary whereas offices were located in the front of the building.
The sanctuary was rectangular in plan with the long dimension oriented east west. The dimensions were 60 feet long by 38 feet wide. Loadbearing walls were positioned along the north and south sides of the sanctuary and was constructed of hollow-block concrete masonry units (CMU) with brick veneer exterior. The block cells were not grouted or reinforced below the top course. Exterior walls were 18 feet above grade or 16 feet above the floor level of the sanctuary.
The roof structure contained wooden trusses; field made with 2 x 10-inch (nominal) rafters and joists. All the connections were hand nailed. Total rafter length was 20 feet. Intermediate chords on the roof trusses were constructed with 1 x 8-inch (nominal) wooden timbers. Bottom chords of the roof trusses were comprised of 20-foot long 2 x 10ís that were butted, spliced, and nailed. The trusses were spaced two feet on centers. Roof decking and cladding were comprised of 1 x 6-inch (nominal) tongue and grooved wooden boards. The roof covering was two-tab composition shingles that contained woven glass mats and were top coated with black granules. These shingles weighed about 240 pounds per square. Tabs measured 17.5 inches wide. Felt underlayment existed beneath the roof shingles on top of the wood decking. The roof had a steep pitch and was 12 feet tall at the ridgeline. Total height of the sanctuary to the ridge was 30 feet.
Rafters and joists were double toe-nailed on each side to flat 2 x 8 inch (nominal) top-plates that were place on top of the CMU walls. The 2 x 8ís were 12 feet long, butted, and toenailed together. Top plates were secured to the CMU walls with 19-inch long steel dowels that were 1/2 inch in diameter and spaced three feet apart on average. The bottom ends of the dowels contained a four-inch flange that was welded to the base of the dowels. The dowels were set in the CMU cells and grouted. These were the only cells that were grouted.
3. FINDINGS REGARDING THE FAILURE OF THE SANCTUARY
The most severe damage to the church was the sanctuary located near the middle of the building. Failure of the sanctuary occurred when tornadic inflow winds from the south broadsided the south wall. The high pitch of the roof and tall height of the south wall acted like a sail to catch the wind. Failure of the sanctuary roof and walls occurred simultaneously as they rotated to the north resulting in the injury of death of the occupants. The south masonry wall fell into the southern one-half of the sanctuary whereas; the roof fell into the northern one-half. In particular, the CMU walls failed along the mortar joint line at the base of the floor and the base of the wall rotated to the north as the joint failed in tension. There was no lateral support for the sanctuary walls which in turn made them quite vulnerable to failure in high winds. The following were some of my findings:
a. It was estimated that failure of the sanctuary occurred with winds at or near 100 mph. Surrounding damage to residences was consistent with this wind velocity estimate and rated F-1 on the Fujita-scale.
b. An interior hallway in the church could have provided adequate shelter for ALL 150 occupants had they sought shelter there.
c. The tornado center passed to the north of the church. The winds which toppled the sanctuary came from the south direction actually preceded the tornado centerline and was on the periphery of the tornadic circulation.
d. As the tornado center passed north of the church, winds at the church switched to westerly and was still strong enough to lift and remove the flatter roof section above the classrooms. Some brick veneer did topple into two of the classrooms.
NOAA should continue to emphasize that people should avoid large span areas during threatening weather and to seek shelter in an interior hallway or bathroom.
Places of public gatherings such as churches and schools should have a NOAA Weather Radio especially with a tone activated alarm.
NOAA Weather radio should have enough transmission power to reach such rural areas.