Depth: Progressive Collapse

A scenario was created where the occupant was changed to the Department of Defense, who required structures to be directly analyzed to resist progressive collapse. The overall goal for this study was to investigate a new and complicated area of structural engineering, while strengthening standard design capabilities.

The Unified Facilities Criteria design code, written by the Department of Defense, will be used to analyze all progressive collapse criteria. All designs will also be checked against the standard ASCE 7 strength and serviceability requirements. The existing two-way concrete slab system was redesigned into a composite steel structural system. This steel stystem was then analyzed using the Tie-Force Method, Alternative Path Method, and Enhanced Local Resistance Method. The linear static approach was used when analyzing the structure for Alternative Path criteria.






MAE Incorperation

Much of the structural calculations relied upon material learned in master-level courses. Multiple ETABS computer models were created to analyze the redesigns. Material and techniques learned in AE 597A, Computer Modeling of Building Structures, was be used to create the models. Several concepts, such as rigid diaphragm constraints, insertion points and panel zone modeling, were used to create the computer models.

When using the Alternative path method of progressive collapse analysis, steel member strengths were largely determined by the connection strength. Due to this limitation, a typical moment connection was designed. Knowledge from AE 534, Steel Connections, was largely be used for this connection analysis.





Breadth 1: Architecture

The architectural impact that several of the structural alterations were also investigated. Specifically, the shift of an exterior column line and the additional structure added to the atrium curtain wall. The existing Revit computer model was altered and images of the alterations were compared. The goal for this analysis was to preserve as much of the existing architecture and program as possible.

The existing site plan was redesigned to meet antiterrorism criteria. A secured perimeter was developed around the project, which created the standoff distance required by the UFC design guide, The existing project location was deemed inadequate, therefore a new site was chosen.




Breadth 2: Construction Management

The goal of this breadth investigation was to quantify the additional cost and schedule impacts made by adding progressive collapse requirements to the design criteria. A detailed cost estimate, using RS Means data, was created for both the base steel redesign and the progressive collapse steel redesign. A more detailed estimate was conducted for a typical moment connection. This connection cost was then used to help compare the two redesigns. A square foot estimate of the existing structure was used as a reference point for these two redesigns' estimates.

Construction schedules were developed for the two redesigns, as well. Only the superstructure was included in these schedules. The existing schedule, provided by the project's contractor, was used as a reference point. The productivity of individual crews was taken into account and used to develope a more optimized schedule. The number of crews needed to produce an effecient construction was made.