This one-of-a-kind seismic slip joint was specially designed and fabricated by Stress Engineering Services for the San Francisco Public Utilities Commission. It is capable of accommodating nine feet of contraction, one foot of extension and an external bending moment of 55 kip-feet and shear of 32 kips. Tests proved it can fully contract in two seconds and is equipped with eight exterior chambers to receive the displaced water during a contraction.
