Transforming a former four-story freight terminal in lower Manhattan that once serviced elevated trains into a 12-floor, 1.3-million-sq-ft hub for Google was bound to require an innovative design and construction program to deliver a workplace fit for a tech industry leader.

当项目团队面对开放新工厂的紧迫时间时，它开发了一种从Bridgebuilding借来的开创性解决方案，可以鼓励更多地利用预制混凝土在纽约市建造核心。

Google will lease and occupy the St. John’s Terminal building at 550 Washington St., which spans two city blocks between Spring and Houston streets in lower Manhattan. It encompasses the southern portion of the former terminus for the old freight line, whose former elevated tracks have become the iconic High Line walkway and park on the West Side.

Railroad tracks are among various preserved and restored features of the classic terminal, which is being developed by Oxford Properties Group with Turner Construction as construction manager and COOKFOX Architects as lead design firm.

项目发言人没有回应确认Google转型成本的请求，但在较早的媒体报道中，估计超过10亿美元。

新建筑剧本

该任务需要确保现有结构可以支持从扩展到12层钢制框架和现场混凝土地板的负载。牛津建筑团队副总裁吉姆·怀特（Jim White）表示，这与两个新的高层电梯核心以及2022年开放的目标，这意味着项目团队必须超越传统的建筑剧本。

Members, which include structural engineer Entuitive, core contractor Rizzani de Eccher (RDE), steel and core erector Metropolitan Walters, and panel manufacturer Jersey Precast, collaborated on a novel solution—a building core of precast concrete panels with matching Lego-style connections instead of a costlier, more time-consuming cast-in-place option. “We had a creative team that pulled together in a positive way,” White says.

他说，匹配技术可以节省时间，并在制造和勃起方面更高。怀特补充说：“我们将预制的限制限制为更高的公差水平。”

RDE的高管里卡多·卡斯特拉卡尼（Riccardo Castracani）说，虽然使用预制混凝土听起来合理地节省时间，但在纽约的高层建筑中没有合适的先例。

“Here we basically built a bridge span but instead of horizontal it is vertical,” he says.

Castracani说，该团队采用“比赛铸造，我们在桥梁中使用的技术，其中一种预制元素是针对以前的预制元素的。”“这样，可以通过下一个部分来纠正任何铸造问题或错误。因此，我们永远不会随身携带错误。我们总是不断纠正，这就是我们将所有东西保持在毫米公差之内的方式。”

Solution Emerges

Venture Capital的合伙人Michael Spies说，比赛过程中的创新可能会极大地使该项目和类似的建设工作受益，但是它需要专有或可申请的软件才能成为独特的产品或可投资概念。在房地产和建筑技术中。

“What’s unique and significant about this is how it’s an efficiency gain,” he says. “If they create a more efficient workflow solution that can work for other projects and don’t have to repeat the brain damage to get there, they’ve created something that has value.”

去年夏天，当没有人知道这将非常适合冠状病毒大流行时，核心设计融合在一起，这使建筑陷入了停滞和受限制的工作场所活动。怀特说，对于终端，干扰最终是最小的，并且该项目仍按计划进行。

他解释说，原因是泽西岛预制能够制定安全的工作场所协议，以使面板的制造能够稳定。Turner项目主管Robert Hubner说，为了架设预制面板，现场工作人员仅占现场团队规模的四分之一，使创建安全的工人距离变得更容易。

他说：“如果我们必须在一个密闭的空间中让40至50人的船员在狭窄的空间中，我们将有很多限制和潜在的延误。”“这是一个无法预料的好处。”

演示和设计

The old freight terminal posed several challenges, starting with complicated demolition tasks, says Brian Jaffee, Oxford director of construction. That work, which began in early 2019, included detaching the structure from a span over Houston Street, which the team demolished to free up a northern tract for another development. The team also removed a fifth floor added by a previous tenant, he says. The “surgical” demolition, along with temporary bracing, created greater lateral stability throughout the entire building, allowing work to proceed on a faster track, White says.

Demolition had begun when the team started discussions about accelerating the timeline, Jaffee says. “We made the change to the precast core somewhere around the summer of 2019,” he says.

几年前，牛津集会了许多帮助它在曼哈顿哈德逊码开发项目的Railyards上建立16跨度的预制甲板的团队。圣约翰大教堂的任务是建造两个单独的14层预制核心，每个核心都将容纳火楼梯和14个电梯轴，从子级到上层屋顶舱室。

“So we used that idea,” says Barry Charnish, principal at Entuitive. “It’s really a vertical stacking of the segmented precast approach, with post-tensioning, both vertically and horizontally. This is connected to a starter system in the basement, which is conventional cast-in-place concrete.”

Strong and Stable

The precast also serves to stabilize the original long and squat structure, which lacked “an identifiable lateral system” and was not “built that accurately,” Charnish says. “We’re also framing it to steel, which required us to be very mindful of the various tolerances. Precast gives us certain advantages in reducing the concern about tolerances.”

他说，需要精确度的需求也适用于核心系统的界面，其张紧杆和耦合器，结构钢连接梁，地板钢和带有变形杆锚的插入板。

这些严格的要求强调核心system’s complexity, says Amir Ulislam, principal at Jersey Precast. “Building something like this, which is being post-tensioned in two different directions and match cast in two different directions, also in two different planes, is really unique,” he says. “A typical bridge segment job is matching to something in one plane or one direction. This is a whole added degree of difficulty.”

Ulislam说，该设计还允许该系统承担所需的负载。他说：“这项工作每立方码的混凝土有大约380磅的钢。”“总的来说，对于结构混凝土，经验法则约为每立方码150至200磅。”

It helped to have Entuitive’s lead project design engineers, David Stevenson and Tanya Luthi, on site both at the terminal and in the fabrication facility, Ulislam says. “These guys are really there with over-the-shoulder inspection and over-the-shoulder problem-solving for conflicts,” he adds. “They would issue changes and guidance on any problem we came up with literally in hours—minutes sometimes.”

Time and Cost Saver

Jaffee说，由于许多因素，预制核心可以节省大量时间，从而将施工时间表缩短了两个月。Charnish说，通过稳定建筑物，团队无需添加一个全新的支撑系统来支持上层钢制的勃起和甲板。他说，相互关联的预制元素还需要少于现场焊接和螺栓杆，而不是现场核心，而端面板的终点是避开干墙以覆盖安装的零件的需求。

The system also streamlined the design and construction process, Jaffee says. The team rapidly moved into shop drawings in the third quarter last year and created the panel mold at the end of 2019.

The first panels were fabricated early this year, with core panel erection starting just as the COVID-19 pandemic swept into New York City, Jaffee says. The team was able to get back on track in late spring when local authorities eased restrictions on construction sites, he says.

Perhaps the biggest time savings is from a simple advantage: With precast panels, the team can use its steel erector, Metropolitan Walters, to assemble the core, Jaffee says.

“That’s where a lot of schedule savings come from, to have the core and steel erected simultaneously by the same erector,” he says. That means fewer trades on site, greater work sequencing efficiency and, notably, fewer tower cranes, says Dave Pisacrita, Metropolitan Walters principal.

Using one trade “to furnish, install and erect a precast system with a steel system, the initial savings is in cranage,” he says. “We only have two cranes on this entire structure. For a building of this size, it could easily handle four to five cranes if there was a subcontractor doing the core. That alone is several million dollars worth of savings for the project.”

简单的优势

A single erector also simplifies work to install 220 precast panel segments, each 50 tons, which total 4,200 cu yd of concrete, 1.1 million lb of reinforcing steel and 500,000 lb of structural steel embedments. With multiple crews, that could be a logistics nightmare, but one erector can avoid the lag of waiting for cast-in-place core formwork and scaffolding to get several floors ahead before steelwork can begin on a particular floor, switching back and forth from steelwork to precast as needed, Hubner says. “It gives us a lot of flexibility,” he says.

A controlled precast installation process is also safer than a cast-in-place core effort involving form and rebar, Hubner says. And the core installation cycle for each floor occurs much faster than with cast-in-place pours, Pisacrita adds.

贾菲说，该团队还使用预制措施，用于楼梯，电梯大厅和填充板，这将节省时间并提高安全性，使钢铁厂和甲板上的船员避免临时梯子。怀特说，随着核心系统的上升，它可以通过稳定结构来使持续的选择性拆除更加安全。

The project team has been trucking panels from New Jersey to Manhattan and assembling the core since late spring and is set to continue the work into the fall, Hubner says. It will start erecting the concrete on metal deck, top out the building and install the exterior in late December. Interior work starts in 2021, with substantial completion in spring 2022, he says.

Another satisfying element of the precast core is the team’s use of a polyurethane-poured mold to create a form liner—an architectural finish that gives the panels a wood planking texture, White says.

While it became a challenging extra feature for the precast fabricator, it allows the panels to serve as finished walls on the interior, avoiding the addition of drywall, he says.

怀特说，蓬勃发展实现了设计团队的愿景“以保持建筑物的真实性及其作为工业建筑的原始历史”。“与其隐藏它，不如将核心变成了一些展示。”