There’s an existing double-decker boulevard under it. An extended double-decker drive runs in front of it. There are buildings to either side. And an existing park abuts it on its fourth face.

要说芝加哥的1,191英尺高的远景塔被挤入周围环境是一种轻描淡写。密集的城市环境为建造101层的Supertall构成了挑战。

总承包商詹姆斯·麦克休（James McHugh Construction Co.

建设始于2016年8月。麦克休（McHugh）去年4月在维斯塔（Vista）上位，这使其成为城市的第三座塔楼，仅次于威利斯塔（Willis Tower）和1,389英尺的特朗普国际酒店和塔楼。该建筑计划于初夏开放。

Well before construction, it was clear that the biggest disrupter would be Field Boulevard that cuts the 52,076-sq-ft footprint in two at the base. That forced some structural gymnastics for the building, which is three stepped towers in one.

对于建筑团队来说，好消息是Lower Wacker的True Calls的更多下行空间。坏消息是，这条切片街排除了75层中部塔楼中传统的钢筋混凝土剪力墙核心。这使Triple Tower的横向负载抵抗系统变得复杂。

这位结构工程师不是三核系统来抵抗城市的大风，而是设计了一个耦合的双核剪力墙组件，该组件将三个建筑物连接起来以进行风力阻力。这两个外核通过一个508英尺高的钢筋混凝土脊柱绑在一起，从上街上的地板15到51。对于重力负载，继续将基础的圆柱（某些位于交通车道之间）支持123英尺长的脊柱壁。

The 2-ft-thick spine transfers wind loads from the middle tower to the cores of the 51-story tower to the east and the 101-story tower to the west. The spine is “simply a mechanism we use to tie the individual cores together so they behave as one,” says David Eckmann, the managing principal of the Chicago office of structural engineer Magnusson Klemencic Associates (MKA).

Designed by Studio Gang with architect-of-record bKL Architecture for Magellan Development Group, the 1.9-million-sq-ft Vista resembles three human figures standing in a row, perhaps watching the boats go by on the Chicago River across Wacker Drive immediately to the north.

The form of each figure, or tied tower, is based on stacked truncated pyramids called frustums. The frustums, each 12 or 13 stories, complicated column lines.

“There is a unique geometry,” Eckmann says.

MKA说，这些碎屑会产生张力和压缩板力，这些平板应在钢筋混凝土结构内解析，后者具有后张紧的地板板。

Chicago’s two-level road system, which creates a false grade, also confuses matters, including floor numbering. The upper level of Wacker Drive along the building’s north face and the Lakeshore East neighborhood abutting Vista to its south appear to be at grade. They are not. The main entrances of all the buildings on the two-level road system are at the false grade, which is the upper street level. The lower level, which is at true grade, serves through-traffic and delivery trucks.

高大的建筑物和城市栖息地的理事会认识到塔的地板高度，实际上是51个故事，75个故事和101个故事。但是，堆叠计划中的地板数从五级停车场上方开始，该车库从真正的等级开始。

In the stacking plan, counting from false grade, the spine runs from floor 11 to 47. A hotel will occupy levels one through 11 from false grade. Condominium residences top the hotel until level 93.

机械空间和控制摇摆的阻尼已高于此。空心的“吹式”地板，可让风穿过建筑物以减少涡流脱落，占地83和84。

The footprints of the three towers are slightly offset. The core in the tallest tower has three cells. North and south core walls align with perimeter walls. The core in the shortest tower has two cells. Only the north core wall aligns with the perimeter wall.

Vista的建筑高度宽高比为40比1。埃克曼说，普通塔约为12比1。

在Vista西端，形成最高塔的多层核心的混凝土墙，底部的64英寸厚到顶部的18英寸。西部核坡度的最外部核心壁遵循堆叠的胶流形状的轮廓。东核使用类似的多细胞核心系统。但是，该核心具有24英寸厚的墙壁，只有一个额外的电池，可延伸至南部。最南端的核心墙壁倾斜沿堆叠的叶状轮廓，类似于西部核心的周边壁。

靠近密歇根湖的摩天大楼坐在沼泽地上，需要深入地基。1871年，大芝加哥大火的残余物被倾倒到湖中，沉积物的积聚将这座城市从密歇根大道（Michigan Avenue）向东扩展，该大道位于维斯塔（Vista）以西，向北延伸。

Vista的圆柱得到了深厚的基础。Vista有124个钻孔码头，其中24个直径为8英尺或10英尺，将大约115英尺延伸到坡度以下，将它们插入6英尺的基岩中。

The remaining foundations are belled caissons that extend approximately 85 ft below grade. The bottom of the belled caissons are “flared” in a layer of stiff clay to increase the bearing area and capacity of the caisson.

Two concrete mats, one under each core, distribute the weight of the cores to the foundations below. The short tower’s mat is 8 ft thick and the tallest tower’s is 10 ft thick.

机组人员为垫子放置了7,000 psi的自固化混凝土混合物。高塔的垫子需要3,560立方英尺的混凝土，并花了10个小时才能完成位置。

Concrete Solutions

Vista is part of Magellan’s Lakeshore East neighborhood. Several of the early buildings in the development have post-tensioned concrete floor slabs.

麦克休（McHugh）在张贴后的平板上具有丰富的经验，在Vista上自我执行的具体作品，就像经常一样。该公司在芝加哥的投资组合包括61层的码头城，98层的特朗普国际酒店和塔楼以及82层的水塔塔，像Vista一样，它也面向湖岸东公园。

Vista,麦哲伦团聚的主要球员the Aqua team, including Studio Gang, MKA and McHugh.

在每个碎屑中，Vista的地板从80英尺的正方形到90英尺的正方形不等。得益于更换地板创建的曲线，如果不干扰公寓布局和视图，周边柱不可能是垂直的。

MKAconsidered sloping columns, but determined that “shifting” each column line slightly to follow the profile of the frustum would be more constructible and economical than sloping columns.

埃克曼说：“我们本可以在周长的悬臂上悬挂板，以保持圆柱（真正的垂直线），但随后您仍然会在某些单位中穿过客厅。”取而代之的是，“我们在每个楼层上踩了5英寸的外围柱，通常遵循冰的形状，”他解释说。

From a structural and visual standpoint, that effectively creates a sloping column line. But there are vertical columns within each story. The solution satisfied McHugh, which didn’t want to build more-complex sloping columns, says Eckmann.

为了容纳风，设计师指定了芝加哥的第一个吹式地板。双高吹式地板没有窗帘墙，使风通过建筑物而不是绕过建筑物。

埃克曼说：“我们不得不停下所有的站点，因为该建筑物是如此高又苗条。”

他补充说：“我们需要从混凝土和倾斜阻尼器中的刚度来管理加速度，并进行吹式地板以减少风力。”

维斯塔（Vista）有六个宽s宽水式减震器，持有超过40万加仑的水。两个荡妇阻尼器在吹式地板上，其余四个在第97层和第99层。

Three-day Floor Cycle

完成停车场和项目的下部后，MCHUGH以每三天的楼层周期开始了上层建筑的占领部分。

船员建造了最远的塔楼，首先是最远的塔。他们跟随最高塔的一半。接下来是中间塔。

McHugh had to be able to walk on a floor approximately three hours after concrete was placed in to keep up with layout work, column forming and floor forming for the next level. Placing rebar, post-tensioning elements, structural steel members and hardware for anchoring the curtain wall followed the next day.

对于地板，麦克休（McHugh）使用一个自攀爬的塔楼，上面放着拖车泵，将其放置在地板上。将落地混凝土通过一个垂直管泵送到每个塔的高度。塔起重机将圆柱和剪力墙的混凝土交付在水桶中，以消除将其与地板混凝土混淆的可能性。

The requirement for the highest modulus of elasticity concrete mix on the project is 7 million psi as an average, with nothing below 6.3 million psi. “We were just as concerned about stiffness as we were about strength,” says Eckmann.

麦克休（McHugh）能够从一年半开始建设开始时保持其每楼三天的步伐。2018年寒冷的冬季至少延迟了一个月。出于安全原因，当密歇根湖吹到90英里 /小时时，无法进行工作。

McHugh was still able to top the structure out in April 2019, putting it on schedule for completion later this year, Kuna says.

The frustums inspired Studio Gang to explore new glass. The units in the wider portions of the building have different thermal performance than the units in the narrower portions, says Juliane Wolf, a Studio Gang design principal and partner.

“The wider areas in the figures’ shoulders [the wider areas of the frustums], essentially heat up more slowly,” she said. “We wanted to select a glass that would mitigate that condition and be tuned to the space rather than have one uniform glass.”

The architect specified different glass shades for visual impact. The waist areas have darker glass and the shoulder areas lighter glass, which brings out the human shape of the figures, Wolf says.

Studio Gang很难找到不同阴影的热等级玻璃的供应商。德国供应商AGC Interpane最终提供了玻璃，它提供了“按需涂料”服务，通过校准渲染屏幕，建筑师可以选择所需的玻璃颜色以及所需的性能值。

AGC Interpane’s coating line can produce the required glass overnight. “We went over to Germany and selected the colors we wanted,” says Wolf. By the next morning, “when we returned to the plant, they had produced a mock-up for us.”

“工作室帮派：建筑,” the first monograph from the Chicago-based architecture firm, will be released in May. It explores 25 of the firm’s signature projects over its first 20 years.