CONTRACTS & CONSTRUCTION
CASE CC1 - Failure of Wall, M. Yachnis
Project: Rotating Arm and Maneuvering Basin at the David Taylor Research and
Development Center, Carderock, Maryland. The structure consists of heavily
reinforced concrete walls and floor slabs. The rotating arm is round while
the maneuvering basin, which is connected to the rotating arm, is rectangular.
Failure of the rotating arm wall.
Symptoms: The structure under discussion is shown in Fig. 5. During the
placement of concrete on the inside face of the wall and at elevations between
128'-0" and 131'-9", the forms failed outwards for a length of approximately
Collection of Facts: The experts review of the collapse concluded that the
contractor had selected forms based on experience and intuition rather than on
structural computations. The concrete was completely disintegrated and the
reinforcing steel misplaced. The cost of replacement of the damaged part of
the wall was approximately $500K.
Solution: Forms are very important elements of a structural system. As such,
they must be analyzed and designed appropriately to withstand to predetermined
loads and carry the stresses given by various codes. Therefore, they must be
approved by a professional engineer as the rest of the structural system.