Fiberglass Trusses, Inc. designs and manufactures prestressed fiberglass beam-trusses and trusses for use in a variety of building applications. Theses fiberglass reinforced plastic (FRP) components exhibit the following unique characteristics which provide advantages over traditional materials such as steel, wood and concrete:
- High Strength/lightweight
- Low maintenance
- Variety of colors/no painting
- Corrosion resistant
- Electrically non-conductive
The above characteristics provide distinct advantages in the following markets: roof and floor systems, canopies and specialty applications. While at E.T. Techtonics, Dr. Johansen designed a number of structures of this type. Some were built while others remained in the conceptual phase due to budgetary constraints.
The University of Pennsylvania’s Mod 6 Chiller Facility was constructed with a lightweight removable FRP roof structure (prestressed fiberglass beam trusses and decking) designed to cover the primary cooling equipment which is submerged in water. FRP was chosen specifically to address the long run maintenance concerns in a wet environment.
In addition, the lightweight prestressed fiberglass beam truss units could be easily installed with a small crane hoist inside the building. The units can also be easily removed when the equipment needs to be serviced for maintenance. Note the “molten” grey color for the decking was specifically chosen due to the architectural requirements.
When Catholic University in Washington D.C. decided to replace a 1970s folded plate concrete canopy system in front of its Engineering School, it looked for a “state of the art” FRP design for its entrance which was very low maintenance. The existing canopy system exhibited some spalling of the concrete which resulted in exposed steel reinforcing that was rusting. The new design used lightweight prestressed fiberglass beam trusses in conjunction with spaced columns.
The light tan color was chosen to match the existing tan brick on the Engineering building. Molded grating and fiberglass sheet were used for the decking elements. Using molded grating allowed light to come thru the canopy system at key points.
Casa Grande Ruins Roof Cover
This conceptual design was developed for the National Park Service for the Casa Grande Ruins in Coolidge, AZ. Casa Grande is a caliche type structure constructed by the Hohokam Indians in the 1300s. A steel roof cover was constructed in the 1930s to protect the Ruins from the harsh Arizona environment. Recently issues had been raised concerning the weight of the steel structure and how it interacted with the existing soil conditions (classic soil structure interaction problem) particularly under seismic conditions. The steel roof cover had not been designed for seismic considerations.
However, due to their lightweight nature, flexibility (low modulus) and bolted connections (high damping) FRP structures have been found to perform very well under seismic conditions. To meet these requirements Dr. Johansen designed a space frame type roof cover with spaced columns which was ½ the weight of the existing steel structure. The design satisfied the seismic criteria necessary for the site and could be easily installed with light construction equipment which would have minimal impact on the historic site.
East Conservatory Greenhouse at Longwood Gardens
An FRP design was proposed for a replacement roof structure for the East Conservatory Greenhouse at Longwood Gardens in Kennet Square, PA. The existing steel lamella arch roof system exhibited extensive corrosion due to the wet environment. It required frequent maintenance and painting which was very costly.
A stainless steel roof structure had been proposed as a replacement structure due to its corrosion resistance but this scheme was very expensive (almost 5 times that of standard structural steel) . FRP offered a cost effective alternative to stainless steel as it reduced the cost by 30%. A curvilinear truss system was developed for the typical 20’-0”x 50’-0” proposed bay. Aesthetics were an important part of the proposed design as a more classical approach was required for the new design.
Chapel in the Pines
A small chapel was proposed in a wooded area at Catholic University in Washington, D.C. The structure required lightweight components that could be easily erected on an inaccessible site with standard hand tools. The material had to be moisture and termite resistant. Aesthetics were also a major consideration.
Dr. Johansen, using FRP beam-trusses and spaced columns, designed a lightweight structure that could be quickly constructed on the site while satisfying the no maintenance requirements. The architectural image reflects the “lightness” of the FRP design.