Inspection Detail

Inspection: 120613047 - Hawaiian Dredging Construction Co

Inspection Information - Office: Hi-E-Honolulu

Investigation Summary

A journeyman plumber received various injuries when the jump form he was working on fell approximately 8 ft. This was a wall form type of construction accident that happened on the south-west corner at the Hawa'iki Tower Number 2 on the 42nd floor. The employee was on the 40th floor deck, adjacent to the exterior concrete wall, during lunch. While resting, he heard noises, and was struck by construction debris. The corner end of the form work for the wall form dropped 8 ft down to the 41st-floor level. This accident happened while the jump form crew was about 15 minutes into their lunch period. This climbing type of form work was being positioned to cast the concrete exterior wall sections on the 42nd-floor level. The system consists of structural steel assemblies secured to the building walls of the previous pour and the elevator core to support a structural steel frame work from where the wall form work is hung. The wall form's interior measured 27 ft wide by 38 ft long by 9 ft high. This system provides climbing capability with nine separate electrical screw type of jacks that are connected to two pair of vertical steel 4-in.-thick by 4-in.-wide by 15-ft-long tube type of legs that are then resting on steel type of knee braces that move up with the jump form's structure to its new height level of 8 ft 5.5 in. There are two steps to raise up this jump form system to its new raised height level and then it's re-bolted and secured to the buildings exterior walls. The first jump step is to raise the jump form system 8 ft 5.5 in. all together. This is the height of the new concrete pour level. This jacking or raising up of the jump form takes about 20 minutes to complete. Each jack consists of 4 legs, 2 exterior and 2 interior legs that each are supported with a 4-in.-wide by 40-in.-long by 58-in.-high steel type of knee-brace mounting bracket with two holes each to secure to the previously-casted concrete wall by through-bolting with two 1.25 in.-diameter by 36-in.-long high-strength coil threaded rods. The exterior pair of jack legs for all nine jacks is released from the wall of the previous pour, retracted (thereby raising it into position for the next pour) and re-secured to the wall with the same four tie rods. The second step of the jump form operation is to go back in the above jack numbered order one at a time and unbolt the inner pair of jack legs and move them up to their new position and reinstall the bolts into the wall and secured. The jack order is then continued eight more times, separately, at which time they will be ready for the new cycle of the operation. In place and secured, one would see eight coil and tie rods securing the jack legs to the wall. The building's core wall precedes by two floor levels. Employees and a yard supervisor noticed there were only three 1.25-in.-diameter by 36-in.-long high-strength coil rods protruding from the down jack. The adjacent jack's jump transition was completed with all tie rods in place and secured. These coil rods were used as the aforementioned "Tie Rods". The 4th tie rod could not be found. As mentioned previously, each leg is supported with a 4-in.-wide by 40-in.-long by 58-in.-high steel-type of knee brace bracket, which is secured to the concrete wall with two bolts each. At the accident location, it was reported that only one of the two bolts specified had been used to secure and support the exterior leg because of obstructions from the vertical reinforcing bars in the enlarged section of the wall column. Based on the above conditions, three of the specified four bolts were used to secure and support the exterior legs of jack number 10 into the wall when the accident happened. Plan layout drawings for the supporting bracket for jack number 10 required it to be secured to the wall with four anchoring bolts. A supervisor mentioned that because only three of the required four bolts were used to secure the two of the four frames at that location the contractor should

Keywords: CONSTRUCTION, LACERATION, FALL, STRUCK BY, FALLING OBJECT, CONCRETE