Local 3 Helps Bring to Life a Building That Breathes
On the corner of Fifth and Wood Streets in Pittsburgh, stands The Tower at PNC Plaza, an 800,000 square foot building owned by PNC Bank. PNC Bank entrusted Gensler as the design architect, BuroHappold as the structural & MEP engineer, Paladino and Company as the sustainability consultant, and P.J. Dick as the construction manager.
This 33-story, mixed-use building achieves new heights structurally and is expected to exceed the requirements for LEED Platinum® status. Teams at Gensler, BuroHappold and Paladino and Company excelled in designing a breathable building. It is an ingenious approach to the new sustainable skyscraper reducing operational costs and focusing on employee interaction within the building.
To achieve the maximum energy reduction and allow 91 percent of the building to be lit by daylight, the project team utilized natural ventilation along with efficient mechanical systems. The double-skin façade creates a breathable building using an exterior weather/air barrier and interior layer with automated air vents and manually operated sliding doors. If it seems a little stuffy at your desk, walk over, slide a door, step into the 3-foot façade opening and get some fresh air…on the 24th floor…of a downtown skyscraper!
The skylight at the top of the tower was designed to allow maximum solar collection. While the double-skin façade pulls air into the building, the solar chimneys draw exhaust and warm air up and out of it; giving the building the option of eliminating fan energy expense for at least 42 percent of the year. With all of the combined green elements—solar chimney, double-skin façade (the only one in the U.S.), etc., a total energy savings of approximately 50 percent is expected. Once complete, the tower should be deemed “the greenest skyrise in the world.”
With over 150,000 ironworker man-hours, bringing the vision to reality was entrusted to top contractors and the highly-trained men and women of the building trades. The Tower at PNC Plaza will have a multi-story underground parking garage, street level retail space, an indoor park featuring seating and an outdoor patio, and house the new global headquarters for PNC Financial Services Group.
Local 3 (Pittsburgh) members had a hand in this project from the ground up. Whether it was reinforcing rebar, erecting garage columns, welding moment connections, erecting the structural steel or installing curtain wall and insulated panels, members worked diligently to complete the tasks. Century Steel Erectors, Miscellaneous Industries, Tri-City Steel, Inc., Permasteelisa North America, AC Dellovade Inc. and D-M Products Inc. were awarded various bid packages for the tower.
Tri-City Steel, Inc. utilized Local 3 members to reinforce concrete with 1,174 tons of rebar and 780,000 square feet of mesh for the parking garage and building. They also built caisson caps around 7-foot high anchor bolts in the foundation. Due to the nature of this innovative green building, Tri-City installed rebar around the thermal breaks (insulation between the exterior and interior curtain wall systems), and welded 408 plates and 1,500 embeds for the curtain wall of the double-skin façade. Tri-City is proud to say that with just under 19,000 man-hours, it was a zero accident job.
Century Steel Erectors was awarded the structural steel package and a portion of the miscellaneous steel package for the tower. They were also responsible for the assembly, dismantling and jumping of the tower crane; the assembly and jumping of the construction elevator; and the furnishing, installation and maintenance of a safety net along the perimeter of the building.
Approximately 50 ironworkers were employed by Century to erect almost 9,000 tons of steel. As fast as the engineering/fabrication could be completed and approved, Century was ready to handle the approximately 500 truckloads of steel. It was their mission to stay ahead of schedule weathering wind, rain, cold, snow and scorching temperatures to make sure two floors were erected at a time and a floor completed weekly. The steel erection started in April of 2013 and topped off on June 24, 2014.
Above floor 33, Century assembled a 64-ton truss, requiring four critical lifts to get it from the busy streets of Pittsburgh to be set and installed! Another notable portion of this project was the “porch” or open-air garden. There were 18,000 pound girders with inch and a half flanges spanning the area to create the porch.
A wonder of the building lies within the innovative double-skin façade mentioned earlier. The ability to let the building “breathe” was left in the capable hands of Permasteelisa North America to ensure the single-story, high-tech glass panes weighing 600–800 pounds wrapped the building. Permasteelisa entrusted approximately 70 Local 3 members to work diligently on the double curtain wall system, podium glass, metal cladding, external doors/entranceways, cable wall and skylight.
For the podium, 105 pieces of straight and curved glass were installed. On January 21, 2014, the first set of exterior units were installed with a Valla and two months later, the interior units were being set with a vacuum manipulator. There are over 4,500 exterior units, the majority being five foot sections containing the mechanical pop-out windows allowing air into the building, and just over 2,500 interior units and 360 sliding doors.
Two exceptional sections of the building are the cable wall and the skylight. The cable wall is a five-story wall system extending from the 28th to the 33rd floors on the west side of the building. In this area, 100 pieces of glass are mounted on 37-millimeter-thick cables that were tensioned between 34 and 37 kilo newton. At the skylight, Permasteelisa’s crew erected the support steel on a 30-degree pitch. They installed 91-4 inch by 8 inch by 7-foot long tube steel columns, and each column had to be individually surveyed and cut to fit before welded to existing stub columns. They also erected 77-5 inch by 5 inch by 30-foot tube steel ladder frames; the installation included a series of bolted and welded connections. Once the support steel was in place, crews used the tower crane and power cups to set the 275 pieces of skylight glass.
In August 2014, AC Dellovade, Inc. brought Local 3 members to the jobsite to install 2,800 square feet of 3-inch insulated metal wall panels on the lower elevation, and in October 2014 the majority of work shifted to the upper elevation. This required extensive coordination of the tower crane to hoist panels at lengths of 30 feet to these upper levels. During this time, they worked at a height of 450 feet with high winds and low temperatures. It was imperative to use additional tethering on the metal panels being hoisted.
Above the 33rd floor, the wall panel elevation was located underneath the solar skylight. Ironworkers had to rig a cable system above the roof beams to secure swing scaffold rigging and life lines for the metal panel install. Staging areas off the intermediate support structure penetrated the elevations to provide mid-point work stations. Dellovade and its crew installed 10,000 square feet of 3-inch insulated metal panel back-up; 11,000 square feet of insulated metal panels; 9,800 square feet of uninsulated metal panels; 3,800 square feet of ACM panels; and 5,400 square feet of vertical louvers.
Upon entering the tower, the interior glass installed by members of Local 3 working for D-M Products Incorporated will be evident. From the all-glass entrances and bathroom partitions to the decorative wall glass in the main and elevator lobbies, D-M Products used the skill set required to handle and install glass. The numbers speak to the impressiveness of the tower: 10,000 square feet of bathroom partitions, 2,500 square feet of lobby glass, 2,300 square feet of glass entrances and 1,200 square feet of mirrors.
Tenants occupying the space will use stairs installed by Local 3 members working for Miscellaneous Industries. Miscellaneous had four to six floors worth of stringers and risers/pans delivered at a time and craned into the building. Only three ironworkers took on the task and erected stairs in the three main stair towers: 838 risers in Stair A, 804 risers in Stair B and 760 risers in Stair C.
As part of the innovative design that promotes collaboration and shared amenities, the west side of the building includes separate two-floor staircases Miscellaneous also installed. These 12 “neighborhood” staircases span the space between two floors and give easy access to sun-absorbing spaces to employees. This feature was pertinent to meet the goal of focusing on employee interaction within the building.
All eyes will continue to be on this project until it is completed. Everyone will watch to see this building “breathe” and shatter the existing mold for a LEED Platinum® skyscraper. It will add more character to an ever growing skyline and give those who worked on it another landmark to say they had a hand in building. The next time you’re in the city of bridges, look for The Tower at PNC Plaza and know Local 3, its members and signatory contractors were proud to be a part of bringing it to life.