Aircraft Rescue and Firefighting

STRUCTURAL ANALYSIS AND DESIGN

Introduction

Aircraft Rescue and Firefighting (ARFF) renovation and expansion includes demolition of portion of existing structural steel. The expansion requires the design of concrete moment resisting frame, owner preferred, with a maximum clear span of 72 feet at the vehicle bay area and smaller spans at both sides for service and storage areas. There is also new mezzanine storage over one of the vehicle bay area.

Building Description

The expansion composed of new building of reinforced concrete frame. Main frame is a gable type of 24” by 48” concrete columns with 72 feet clear span beam measuring 48 inches at the column support tapering down to 36 inches at mid span intersection. The building has side frames that support stability and resisting lateral loads while continuous frame were used in the longitudinal direction. In general, the building is a special moment resisting space frame. The concrete roof slab in between frames transfers the lateral forces to the main frames down to the foundation. This will achieve the proper load path of this high one story but massive concrete structure.

The building has a perimeter parapet along the main frames. Side parapet has as high as 10 feet while front and back parapet has as high as 15 feet. Openings at the front and back are provided with Bi-fold type doors while roll-up doors were provided to the side frames. Cranes with 5 ton capacity were also provided at the service area.

Proposed Aircraft Rescue and Firefighting Renovation and Expansion – Isometric View

Because of the high allowable bearing capacity of the soil at the site, the foundations for the extension are to be on spread footing. Frames adjacent to existing building were to rest on the footing of the existing building that has to be strengthened depending on the additional loads imposed by the new concrete frame.

The renovation consists of replacing the existing pre-engineered building’s metal deck roofing with concrete roof slab and the existing metal cladding with concrete masonry (CMU) walls.

There are 2 inches gap between the new and existing structures to allow for movement during strong earthquake and typhoon.

Building Site

The building occupancy category falls under essential facility. The seismic design will be in accordance with Chapter 19 of the UBC 1997. Building lateral forces are calculated based upon LRFD load combinations in UBC section 1612.2.2 and the base shear equations in section 1630.2. The building is located in Seismic Zone No. 3 with the following site conditions:

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