Prehistoric Prairies Discovery Center
Crawford, Nebraska

The paleontologic discovery of complete mammoth skeletons locked in combat in the Nebraska National Forest justified the construction of a Visitor Center to allow the public to view the skeletons and introduce other noteworthy attributes of the area. JFSA designed and produced construction documents for this structure.

Considerable effort was expended in the Architectural design of the facility. The final layout, with stone veneer walls sloped at 15 degrees from the vertical, three different roof levels, an open interior, and various other features, created a design which blends with the surrounding plains and at the same time gives the impression of great age. It also created significant challenges in the Structural design.

Wind induced shear forces developed in the roof diaphragm of this 12,000 sq. ft. structure had to be transferred to perimeter shear walls and braced frames. With no internal shear walls or braces, the steps between roof levels had to be carefully designed to transfer both shear forces and diaphragm chord forces.

In most areas, the spaces formed inside the sloping walls were to be used as alcoves for housing displays, this limited the locations where bracing could be employed and drove the design to rely primarily on shear walls. The shear walls themselves were a challenge, as, due to their slope, they had to be isolated from vertical loads. For this purpose, special connectors were designed which could be field located as the shop fabricated wall panels were installed. Since the base of the walls did not coincide with the columns, dedicated shear wall tie downs were provided at all corners and openings.

Increasing the design challenge even more, the geotechnical investigation indicated the native soils to be collapsible, requiring low foundation loads, significant over excavation and replacement, and careful detailing of underdrain systems and site grading.

Client: U.S.D.A. Forest Service