22-05-2012, 03:36 PM
Structural Design
Design of tall building.pdf (Size: 1.42 MB / Downloads: 347)
Problem Statement and Assumptions
This report outlines the design of a ten-story steel frame hospital located in Memphis,
Tennessee. The building’s plan dimensions are 80 ft by 320 ft, with column spacing of
30-20-30 ft along the short dimension and 32 feet along the long dimension, as shown in
Figure 1. Typical story heights are 15 ft, except for the first two stories which have
heights of 20 ft each to allow for procedure rooms.
Architectural and Structural Features
Cladding around the perimeter of each of the first two 20-ft procedure-room stories and
next eight 15-ft patient room stories is cosmetic brick weighing 60psf. Initial design
constraints limited the design to include only members W36 and smaller and weighing
less than 300 lb/ft, with moment frames only along the exterior in the 320-ft direction,
and a maximum of four lines of bracing in the 80-ft direction. The hospital contains two
service elevators at each end and a bank of four public elevators in the middle, as well
as stairs. Corridors run through the center of the building in the long direction.
Design Technique and Philosophy
Design was conducted according to ASCE-7-05 and the AISC Steel Manual 13th edition.
The LRFD approach was used as a design criterion. All load combinations were
entered into the model, and the combined load effects were compared to the reduced
nominal strengths of the members. In addition to analyzing members under typical
load effects, for seismic design, a drift criterion accounting for plastic deformation was
Roof Live Load
The roof live load was also determined according to ASCE-7, section 4.9. The roof live
load used was 20 psf. The roof live load was patterned in the same manner as the live
load to maximize load effects.
Snow Loads
Snow loading was calculated to be approximately 20 psf, applied uniformly over the
roof area. No drift of uneven snow loading was included.
Lateral Loads
Because Memphis lies within an area of high seismic risk, the design of the lateral
system was expected to be controlled by seismic loading. Nonetheless, the proper wind
and seismic loads were calculated according to ASCE-7 and included in the building
model.
enforced as indicated by ASCE-7.