Steel Construction Vol 40 no 6 - International Steel Structures | Page 20

SAISC projects LEFT: Substructure (left) and superstructure (right). BELOW: A girder before removal (left) and after removal (right). GMS ft each) by one east-west bay (18 ft, 6 in.). Creating the storefront at the lobby also required removing two wind girders at the second floor, which represented 20% of the floor stiffness at that level. To compensate, the wind girders overhead and in adjacent bays were reinforced, as were the columns that support them. Girders at the second floor are reinforced with 1.125- in. plates at the top and bottom flanges; the third-floor girders are reinforced with WT7×79.5 at bottom flange. Existing built-up columns consist of W14×426 with 6-in. flange cover plates. These were further stiffened with Project Team Developer: Equity Office, New York Architect: MdeAS Architects, New York Structural Engineer: Gilsanz Murray Steficek, New York General Contractors: Shawmut Design and Construction, New York Structure Tone (plaza), New York Steel Fabricators, Erectors and Detailers: United Structural Works, Congers, N.Y. Burgess Steel, Englewood, N.J. GMS new 2-in. by 18½- in. fitted reinforcing plates added between the flanges, forming a box and providing stiffness necessary to counteract the increased unbraced length. The two end columns that had supported the removed wind girders also have new 1¼-in. flange plates (over the original plates). The demolition and installation procedure followed a specific sequence to safeguard the building’s ongoing stability during the work: 1. Install column cover plates between the second and third floors 2. Locally remove the slab around the columns and install temporary struts (HSS10) 3. Install a double hanger from temporary struts to the existing east-west beam (W24) 4. Remove a portion of the existing W24 proximate to the western frame 5. Reinforce the perimeter wind girders 6. Complete column reinforcement between first and second floors 7. At the second floor, demolish the remainder of the slab and the W24 beam and temporary strut assemblies Refurbished retail The final component of the project was the redevelopment of the 1095 tower’s frontage along 42nd Street with a new doubleheight retail space at the western corner, which connects the street to the concourse beneath the plaza. To the east of this corner space, new stairs and a glass elevator provide access to the subway station beneath the Avenue. However, a moderate elevation difference between where the stairs and elevator land below grade and the entry to the subway station required a ramp structure, which was obstructed by existing framing at the underground concourse level. Similar to changing the grade between the Cubes and the plaza, a bent beam was installed to support the ramp from a lower elevation. The tops of the existing beams were coped 4 ft from the foundation wall and new 8-ft lengths of beam were added below, bolted to the existing beams’ bottom flanges, with a 4-ft overlap. The lower member sits on a channel seat at the foundation wall. Dramatic destination Originally initiated as a plaza restoration, the project was reconceived into a $22 million white box development (the Cubes) and $14 million reconstruction (plaza and 1095 tower). In 2015, the entire property consisting of the Cubes and 1095 Avenue of the Americas tower was sold by Blackstone to Ivanhoe-Callahan Capital joint-venture for $2.2 billion – at that time the largest transaction for a U.S. office building since 2008. “There is a high demand for new retail space away from the traditional Fifth Avenue shopping district as more brands begin to scout locations lower on Fifth Avenue or closer to Times Square,” said William Pisani, vice president of Shawmut Design and Construction. Whole Foods is taking two floors of the 1095 tower at the Avenue and Pandora occupies the plaza-side retail corner. The glass and steel structure solidifies the plaza’s prominence as an active destination by surrounding the plaza above and below grade with retail spaces. One of the Cubes’ first retail tenants was an Asics store, which incorporated a 7-ton NYC subway car into its space – a unique retail experience for a unique structure. GMS 18 Steel Construction Vol. 40 No. 6 2016 GMS The authors would like to thank Petr Vancura for his help in writing this article.