Award of Excellence: Special Projects Category
Structural Repairs to the Catholic Church of St. Joseph
Submitted by Construction Technology Laboratories, Inc.
St. Joseph Parish
Construction Technology Laboratories, Inc.
Oscar J. Boldt Construction
Stevens Point, Wisconsin
Conway Universal Studios (Stained Glass Restoration)
The Catholic Church of St. Joseph in Menomonie, Wisconsin, was built in 1963. Its most innovative and expressive architectural feature is its saddle-type, hyperbolic paraboloid concrete shell roof. At the southeast corner of the structure, the roof shell projects outward beyond the exterior walls to form a canopy over the main entrance. This canopy is supported by its continuity with the roof shell and by two brick masonry fin walls that project outward from the main walls toward the canopy shell edges. These fin walls extend upward from grade approximately 50 feet to the curved soffit of the canopy shell.
The church’s original designers had only closed-form methods to analyze the shell structure, and their design for the canopy pushed the limitations of the available analysis methods. After 36 years in service, the fin walls had bowed, the masonry was cracked, and the tops of the fin walls had displaced significantly. The fin walls were slipping out from beneath the canopy, and as a result, large sections of masonry were in danger of falling and the roof structure was on the verge of serious damage.
Using techniques unavailable at the time of original construction, engineers developed a finite element model of the church structure to study the condition of the structure and the fin wall/canopy interaction. The model was subjected to gravity loads, creep, and seasonal thermal changes, and then used to identify structural demands on the fin walls. This led to an understanding of the observed behavior and an appropriate repair design, including shoring methods to support the shell during the repairs.
The investigation and repairs not only averted a potentially dangerous failure, but also preserved the building’s architectural character and allowed the church to remain in use through the entire course of reconstruction. Matching brick from the original supplier were used to construct new reinforced masonry fin walls. Original stained glass windows were carefully removed, stored, and reinstalled in the strengthened structure. The investigation and repairs saved this landmark church and helped extend its useful life for many years to come.