Project Description:
At first glance of the project statistics below you might think this was a rather ordinary project, but as you can see by the surrounding pictures, this project is anything but ordinary. Our scope on this particular project consisted the forming and shoring of the zigzagging beams above the main people mover loading areas as well as the slanted battered walls at the north end of the project, the large support beam at the south end of the structure and miscellaneous intermediate slab areas and walls.
The most unique aspect of the project is the beams that span over 100 feet from the south side of the below grade terminal to the slanted battered wall at the north side. In half the area the floor to floor height was in excess of 40 feet and the remainder was just over 20 feet. The beams were incredibly unique; the sides were battered, the bottom sloped, the ends were faceted and they were cast with white concrete, but the most interesting characteristic was the exposed post-tensioning system utilized to make the over 100 foot span.
The exposed post-tensioning system consisted of two 2 ½” braided steel cables attached to extremely large structural steel embeds at each end of the beam. The cables draped from one end of the beam underneath a large “king pin” anchored to the bottom of the beam located just shy of the mid-point and then back up to the anchor at the other end. The “king pin” was equipped with large adjustment nuts which when rotated would induce tension into the cable and in turn uplift into the “king pin” lifting the beams to the desired elevation. After the required post tension force was achieved the shoring and ganged formwork was carefully stripped and removed as to not damage the exposed post-tensioning.
The angled layout of the beam shoring was quite elaborate, but became even more interesting when the shoring was required to span over the track areas to accommodate acceleration of the track installation. Large steel I-beams were used to span the track area and continue up the required beam shoring.
Project Portfolio Overview
