Site visit: October 17, 2017, Time:14:30–16:00 hrs
Observations: We were offered to walk on the construction site this visit. The project engineer provided hard head, glasses and safety vest for our protection and informed us to wear hard soled shoes in the last visit.
The trip started with explaining the status of the ramp excavation on site. There were two machines on site one focusing on chipping the excess stone on to the wall and the other excavating machine focused on finishing the excavation process. The bump was saved for the end because, it did not provide ease of access to reach and chip stone because of the elevation it is in. And the ramp was anyway filled with dirt and the stone reduced the soil pour.
Then in the next stop, the project engineer mentioned the kind of sub-contractors involved in the construction, and how they were involved in the design from the beginning. The elevator mechanism used in the project was one of the first one in the north america, and so the elevator sub-contractor was one of the first ones to involve in the design. The towers have distributed complexity and work force is organized accordingly on the site. The picture above shows a view of both the towers under construction.
Concrete slabs are tricky things if not handled carefully. Due to the temperature changes throughout the year from winter to the summer, the slab both expands and contracts when compared to the actual built in size. This tends to become a problem because expansion brings cracks on to the slab, and they cannot be avoided. So designers came around the problem with a solution by directing the cracks and monitoring them. So slabs are cut at particular places in a specified manner to direct cracks there. In the photo above, the worker can be seen cutting the concrete deep enough and not too deep to prevent from breaking it. This will direct the crack here, and it can be monitored accordingly.
The picture above shows a construction joint to connect a portion of slab that was not built. This portion was left open to provide staircase which gives access to the various levels of the building in construction. Once the construction reaches its final stages where access is provided by the actual elevators and staircases, these access staircase is then removed and slab will be completed. This is then joined by removing the wood joint shown and will be filled with the concrete poured to increase the bonding between slabs.
The photos above show workers on site, lifting scaffolding, cutting slabs, monitoring activities and idle ones too.
The photos above show how scaffolding is generally brought in by cranes and fixed into place. The ones that are not fixed right away are kept down next to the erection place like shown in the photo in the middle.
Photos above show reinforcement bars dumped on site. The slabs above parking deck are reinforced in the post tension mechanism. In post tension process, the reinforcement laid is not taut, and concrete is poured. But once the concrete sets to a certain limit, the bars are pulled from the sides to create an inverted u shape which reduces the sagging of the slab once loaded. Material dumping is generally done on site on the levels where materials are going to be used in the erection process. The reinforcing bars above are kept on site to use them in slab erection on the same level.