Cantilever repairing

Problem: At the main terrace level of the structure, strengthening is required including bonded post-tension tendons parallel to the cantilever girders, and un-bonded tendons in the transverse direction.

Structure Details: The tendons start at points near the bottom of the existing concrete members and gradually rise up to the top of the existing beams at mid-span. This created a lifting effect, or positive bending moment, on the cantilevers when the tendons were stressed. Special care was required during construction to prevent damage to architectural features and landscaping.

Repairing Methodology: The strengthening plan has called for steel channel beams to be bolted to each side of the master level concrete joist which is directly above the four 'T'-shaped mullions. These channels ensured that the beam has sufficient strength to achieve the proper transfer of forces from the living room to the master terrace. Like the post-tension cables at the main level, these channels are hidden in the floor cavity.

Another aspect of repairing team’s work involved repair and strengthening of the master level parapet walls. These walls have experienced significant cracking due to the cantilever deflections. Three 14-foot-long FRP (fiber-reinforced polymer) bars were epoxy-grouted into narrow grooves which are cut into each of two parapet walls. In addition to the new bar reinforcement, a significant amount of epoxy crack injection repair was performed by VSL on the parapet walls. Because of the pristine nature of falling water's setting, restoration and repair activities were conducted with care to minimize the environmental impact on the stream, the falls and the landscape. Protective canvas and shielding along with regular cleanup were used during the project to keep the nature.