Foundation

The foundation system used in Macalister Hall is the most common system used at Drexel:  drilled piles.  The type of piles used at this location is assumed to be concrete. 

Concrete piles can be either precast or cast-in-place piles.  Precast piles are manufactured ahead of time, delivered to the jobsite and driven into the ground.  Precast piles are cast to the desired length and cured before they are delivered.  They are prepared using steel reinforcement and can be square or octagonal in cross-sectional shape.  The reinforcement is added to allow the pile to resist the bending moment during delivery to the site, the vertical loads, and the bending moment caused by lateral loads such as wind.  

Cast-in-place piles are built by digging a hole in the ground and then filling it with concrete.  This type of piles can be categorized in two ways:  cased piles and uncased piles.  Cased piles are made by a steel casing drilled into the ground and then filling the casing with concrete.  At the bottom of the pile a pedestal is placed which rests on the bedrock for stability and additional bending moment support.  Uncased piles are made by drilling a hole and then filling the hole with concrete.  The soil provides the “shell” in this case rather then the steel case. 

This building is assumed to have cast-in-place cased concrete piles resting on the bedrock.  The specific type of pile is assumed to be Western uncased based on the depth of the pile.

            There are advantages and disadvantages of this type of foundation.  One advantage is that it is relatively cheap.  Another is that there is the possibility of inspection before pouring the concrete.  This can eliminate some unforeseen problems with the soil, casing, or pedestal.  Cast-in-place concrete piles are also easy to extend.  This solves some of the problems that precast piles would have.  For example, if the bedrock isn’t to the exact depth the engineers thought it should be at.  Soil borings and testing can be very expensive when many are needed.  With cast-in-place piles, the bedrock depth is approximately known and the concrete is poured until it reaches it.  The disadvantages of this system are that it is difficult to splice after concreting.  Also, if a thin casing is used, it may be damaged during drilling.

Framing Section