changing market forces and their impacts on tall building ... · the win was short-lived as the...

CTBUH 2016 Shenzhen · Guangzhou · Hong Kong Conference | 2016年CTBUH深圳 · 广州 · 香港国际会议 345

Precursors

The project started with a design concept commissioned by one of India’s premiere development companies in 2012 for an iconic luxury residential tower. Designed by Smith Gill, the architectural firm renowned for the one-kilometer-high Jeddah Tower, the 116-story, 400-meter-plus tower (Figure 1 & 2) was designed on Western typologies and depicted an organic footprint and a highly textured façade. There was much discussion about the tower’s ability to “confuse the wind” and how the design represented global sensibilities and world-class architecture.

The win was short-lived as the client subsequently and in quick succession dropped the design due to investor pressure for an even more “iconic” presence in the city. The preferred alternative concept was a vertically undulating tower that would stand out among the city’s cacophonous skyline. As conceptualized by a local firm of repute, the tower cantilevered and recessed up to 18 meters, and the design was soon given the green light by stakeholders. However, it was immediately delayed by the city’s regulatory institutions, especially the government-appointed High Rise Committee, a collection of academic and lay experts who summarily reject non-traditional methodologies or any cantilevers over 2 meters.

Changing Market Forces and Their Impacts on Tall Building Planning and Design: A Case Study

This paper articulates how changing market conditions and other variables impact the design process for tall buildings in general and a 355m tall luxury residential tower in the city of Mumbai, India, in particular. Although the contents define the design evolutions in some detail, specifically regarding architectural and structural explorations, the major thrust of this expose is to evaluate how fast-evolving markets, regulatory constraints and shifting economic conditions radically affect the design and construction of such projects and create new paradigms of the design process.

Keywords: Building Codes, Construction, Economics

此文件清楚地表达印度孟买的商业市场及其他因素是如何影响到当地的高楼及355米的豪华住宅设计。此方案设计的推力除了来自于建筑细部及结构的研究优化，最主要的目的是评估当地市场的快速成长，法规限制，及经济体系的动向是否会影响到项目整体的设计。

关键词：建筑规范、施工、经济学

Abstract | 摘要Ro Shroff | 罗史洛夫 Senior Vice President | 资深副总裁 CallisonRTKL 凯里森RTKL Seattle, USA 西雅图，美国

A graduate of Illinois Institute of Technology, Ro Shroff is a Senior Vice President of CallisonRTKL and has been associated with the firm for over 22 years. As the firm’s appointed lead for Tall Buildings, he is responsible for design, client management and business development in global markets, specifically China and South Asia. Current tall building projects under his direction include Imperial 3 / 355m (Mumbai, India), Chongqing WTC / 325m (Chongqing ), Yintai International Plaza / 240m (Chengdu, China), Meixi Lake Towers / 260m (Changsha, China) and Alta Monte / 260m (Mumbai, India).

罗·史洛夫毕业于美国伊利诺伊理工大学。作为凯里森RTKL资深副总裁并有二十二年的经验，罗监督并指导中国及东南亚市场的高层建筑项目。现任监督的项目有Imperial 3/355米（印度孟买）、重庆WTC/325米（中国重庆）、银泰国际/240米（中国成都）、梅溪湖高楼/260米（中国长沙）及Atla Monte/260米（印度孟买）。

市场趋势的变化及其对高层建筑规划设计的影响/案例研究

背景

最开始是在2012年，由一家知名的印度开发公司委托设计一座标志性的豪华住宅高楼。该住宅楼由史密斯和吉尔建筑事务所设计，该事务所曾设计了著名的高达一千米的吉达塔。这座住宅高楼共116层，高度超过400米（图1、2），属于西方建筑类型，底部简洁，大楼正面极有质感。外界很多人都在讨论这座高楼可以“混乱风向”，以及这种设计代表了全球鉴赏力水平和世界级建筑水平。

然而，好景不长，委托人后来紧接着就否定了这一设计，因为投资人想要一座在该城市更具有”标志性”的存在。他们更中意的构想则是一座垂直波状高楼，它将高高耸立在这个喧嚣的城市的上空。根据当地知名公司的构思，大楼悬臂梁伸出和凹进部分长达18米，这一设计很快得到股东们的通过。但是，这个设计却被城市监管机构拦了下来，尤其是政府任命的高层建筑委员会，集合了一批学究和外行，对于非传统方法学和任何超过两米的悬臂梁统统说不。

欢迎来到孟买，一个有两千万人口， 2500亿美元GPD的混乱之都。这是一个金融巨头缩影，超级富有，然而基础设施崩坏，交通堵塞令人窒息，并且人口极其密集。这是第三世界国家的一个大都市，被称为伟大的人类之都，并象征着企业家精神，但它经常被拿来和它的中国对手上海做不利比较。

Volume 1 and 2 book.indb 345 9/12/2016 8:02:42 PM

346 Urban and Megacity Case Studies | 城市和巨型城市案例研究

Figure 1. Adrian Smith + Gordon Gill Architecture concept (Source: AS+GG)图1. Adrian Smith + Gordon Gill Architecture建筑事务所概念（来源：AS+GG）

Welcome to Mumbai, a chaotic city of 20 million with a GDP of $250 billion that is at once the epitome of financial brawn, uber-wealth, crumbling infrastructure, choking traffic and extreme density. A third-world metropolis that boasts great human capital and entrepreneurial spirit, the city often negatively suffers comparisons to its Chinese counterpart, Shanghai.

Midway through the design process, CallisonRTKL was appointed as the primary design consultant to bring in a world-class aura to this fledgling concept, endowing the tower with grace and finesse and imbuing it with global sensibilities, while retaining the approved design direction. The client instituted a new team of local and international consultants and restarted the design in early 2015.

This is a case study examining how the design continues to morph and evolve given the vicissitudes of market demands, competition from similar inventories, political influences, financial wherewithal and fluctuations and most importantly technological, constructability, delivery and logistical challenges. Although the paper articulates the evolution of some of the design features and components of the tower, it is secondary to the notion of how design, especially in the supertall arena, continually evolves and re-invents to accommodate and respond to market variables.

在设计途中，CallisonRTKL被任命为首席设计顾问，为这一新手构思带来世界级的光环，赋予这座高楼优雅和灵巧，并为它注入国际鉴赏水平，同时保留它已通过的设计方向。该项目委托人组织了一只由当地和国际专家组成的队伍，在2015年年初开始重新设计。

这个个案分析阐述了，时刻变化的市场需求，类似建筑库存的竞争，政治因素，金融手段和资金波动，尤其科技，施工能力，交付和后勤方面的挑战，是如何使建筑设计不断改变和演化的。尽管本文阐述了一些设计特征和塔楼组成部分的演化，然而了解设计、尤其是在超高层领域的设计，是如何不断演变和进行再创造以适应和应对市场变量，更加重要。

条件及影响

要评估这座大楼和其他标志性超高层建筑（几乎都是在豪华住宅类型）在这座喧嚣的城市里为何在蓬勃发展的同时却又停滞不前，就要先了解政治和建筑法规因素是如何影响这类工程的展开的。在这个人口超过十亿的国家，有五十个城市人口超过了一百万，显然，孟买不是这个国家的代表城市。这是一个独一无二的产物，一个复杂的集合体。这里土地极其匮乏，房地产市场和购买力高度膨胀，贫民窟随处可见，各政党吵闹不休（还常常受制于地下黑手党大佬们），股市蓬勃兴旺，还拥有与其他全球都市相当的跨国投资。

在史上最长一段时间内，孟买的容积率一直限制在1.0以下，这主要是因为政治因素而不是实用限制。由于孟买外形和曼哈顿类似，是一个半岛，它没有任何地方可以扩张，因此，要解决不断飙升的人口数字问题，限制建筑物的高度是毫无道理的。这导致了城市的任意发展，非法占用公地和贫民窟随处可见。最终，逻辑取胜，两个倡议实现了发展扩张，但成功率各不相同。第一个是将制造业，尤其是一些关闭的棉纺厂，移出城市边界，从而空出孟买中心的大面积区域，用来建造豪华的购物中心和商业办公区域，打造一个全新的中心商务区。这样一来，就十分不利于孟买南部尖端地区原有的”市中心”的发展。另一个倡议叫做贫民窟改造授权方案。该方案为开发商建造高密度或豪华住宅大楼提供额外激励措施，即负责为现有棚户区居民解决生活问题，为他们在排列密集的、30层高楼上提供永久住房。 “压力阀”开启了，人们又可以在250平方英尺户型的新城市街区的附近大肆开发高层住宅楼。这让人们想起了美国二十世纪六十年代Pruitt Igoes和Cabrini Greens的两则失败社会案例。

正在制定中的新倡议包括更高的容积率（提高到5），开发权利转移（在转移过程

Context

To evaluate how this and other iconic supertall towers (almost exclusively in the luxury residential arena) in this bustling city continue to flourish and stagnate at the same time, it is important to understand the political and regulatory implications of how such developments are initiated. Clearly, Mumbai is not representative of this country of over a billion people that has more than 50 cities with populations of over one million. It is a unique anomaly and amalgam of extreme paucity of land, highly inflated real estate and buying power, teeming slums with abject poverty, a raucous political system (often undermined by underworld “dons”), a thriving stock market and multi-national investment on par with other global cities.

For the longest time, the city’s Floor Area Ratio (FAR) was limited to less than 1.0 and influenced by political rather than pragmatic constraints. With no place to grow or expand due to its Manhattan-like island configuration, it made little sense to restrict height and development to keep pace with a burgeoning population. This led to haphazard growth and the proliferation of squatters and slums. Ultimately, logic prevailed and two initiatives allowed development to expand with varying success rates. The first was to move manufacturing and industry—essentially defunct cotton mills—out of the city’s confines, thus allowing large tracts of

Figure 2. Adrian Smith + Gordon Gill Architecture concept (Source: AS+GG)图2. Adrian Smith + Gordon Gill Architecture建筑事务所概念（来源：AS+GG）



land in central Mumbai to be converted to glitzy malls and commercial office space and creating a new CBD of sorts, much to the disadvantage of the southern tip of the city, its quintessential “downtown.” The other initiative, the Slum Redevelopment Authority Scheme (SRA) offered developers additional incentives to build high density or luxury residential towers if they would rehabilitate existing slum dwellers at their cost, by providing permanent housing in 30-story cheek-by-jowl towers. A pressure valve was lifted, allowing rampant development of tall residential buildings in close proximity of the new urban blocks of 250-square-foot apartments, recalling the failed social experiments of the 1960s in the US that disastrously led to the Pruitt Igoes and Cabrini Greens.

New initiatives currently under way include higher FARs (up to 5), Transfer of Development Rights (TDRs) in which additional FARs can be purchased at market prices, revised parking regulations and new regulatory oversights. However without full transparency and lack of clarity, builders and developers are continually stymied in proceeding rapidly, further exacerbating completion and delivery schedules. The current design for this tower is expected to take five years to complete—a 30% premium in time taken in other contemporary cities such as Shanghai or Dubai.

The precursors to this case study were the 240-meter-tall twin Imperial Towers, home to the city’s upscale social echelon and a manifestation of such an SRA initiative. Built on a hilly terrain with expansive city-scape and Arabian Sea views and completed in 2010, they became instant icons in the city skyline. A series of new developments, several in excess of 300m height continue this trend of co-existence of the influence peddlers and their maids and chauffeurs, living within close proximity on small linear patches of land.

A key anomaly in residential towers of this ilk is how to maximize saleable area and minimize “load-factor” baggage to unit design. All cores have certain designated areas (in front of elevators or stairs, etc.) considered “free of FAR,” meaning they are not counted towards the overall area consumption and hence benefit the buyer in terms of saleable areas, given that many of these towers sell for $1,000 per square foot or more. Many tricks are employed to alleviate any or all of these constraints, including specifying additional elevators, the cost of which is easily subsidized in the entire project cost but greatly enhances the sale attractiveness.

Explorations

Imperial 3 essentially evolved from the same pre-requisites bordering one of the most desirable neighborhoods of the city and close to the Antilla, the billion-dollar tower for the country’s richest industrialist. Situated on a 3.5-acre greenfield site next to the existing twin towers, Imperial 3 is oriented in an east–west direction, enjoying extensive sea and cityscape views. The terrain allows the tower to be perched above its surrounding context and an eight-level parking podium allows it to be close to 400 meters in height within the adjacent context. With a roughly rectilinear footprint and a central linear core, the two ends of the tower bulge out and recede, creating a serpentine and undulating form rising to 355 meters and creating a commanding presence on the city’s continually developing skyline (Figure 3).

Accommodating up to 180 units (a mix of three- and four-bedroom apartments with wrap around decks), the 70-story, 355-meter tower accommodates approximately 155,000 square meters (1.66 million square feet), excluding a 1,000-space parking deck. The typical floor plate, approximately 2,000 sm (21,500 sf ) in area, is essentially an elongated rectangle with flared corners. Four units (three- and four-bedroom) straddle the four corners, anchored by a linear core accommodating twelve passenger elevators (with speeds of 6 meters per second) and two service elevators in addition to exit stairs and shafts. The core walls range from 1,000 millimeters thick at the lower floors to 450 millimeters at the upper levels. Major slivers of the core are essentially voids, as the tower ascends outwards and recesses back to give the tower its unique profile. Four triplex units and two half-floor three-level penthouses cap the structure culminating in a 30-meter crown / lantern feature (Figure 4).

中，额外容积率可以以市价购买），修改的停车规则和新的建筑法规。然而由于缺少透明度，建筑商和开发商很快又会遇到种种阻挠，严重影响了施工进度和交付计划。目前来看，这座住宅楼的设计将在五年内完成，这个耗时比当代其他城市，如上海或迪拜，要多出30%。

这个个案分析的先例建筑是240米高的双塔帝国大厦（见图3）。这是孟买上流阶层的居所，同时也是贫民窟改造授权方案的产物。它建造在丘陵地带，城市风光尽收眼底，还可欣赏到阿拉伯海的美景，于2010年完工，之后立即成为了城市天际线上的象征性建筑。一系列新的建筑物都顺应着这种趋势（其中好几座大楼都超过300米），有权阶层住在高层建筑中，而他们的侍女和司机则住在附近条形的一小块地方。

此类的住宅大楼一个关键的特性是将单位设计的可出售面积最大化，并将“负载因素”配备最小化。所有的核心筒都有指定区域（如电梯或楼梯前方区域）不计算在容积率之内，即这些区域不计算在整体消费区域内。考虑到这些大楼每平方英尺售价都在一千美元之上，这些区域对于送给购买实用面积的买主来说，就是一种福利。而开发商会想出各种各样的手段，来躲避部分或是全部的限制，比如，增加电梯数量，这项成本能轻易在整体工程项目中得到补贴，还能增加销售吸引力。

探索

帝国大厦3也是从相同的先驱建筑演化而来，它坐落在城市最理想的社区边上，靠近于安蒂拉——这座耗资十亿美元的、臭名昭著的大楼里住的都是印度最富有的实业家。帝国大厦3站立在3.5英亩的新地皮上，临近双子帝国大厦，它东西朝向，能够俯瞰广阔的海景和城市风光。它所处

Figure 3. Mumbai context (Source: CallisonRTKL)图3. 孟买环境（来源：CallisonRTKL）



Picking up on the undulating sine curve form as a pre-determined given, CallisonRTKL explored several alternative aesthetic directions to imbue the tower with a definitive identity and elegance (Figures 5, 6, and 7). They ranged from a Miesian “less is more” concept devoid of all extraneous ornamentation, to a structurally expressive exoskeletal structure and finally to nautical references that allude to waves and sails, an obvious choice given the city’s maritime history and geography. Other concepts included a pixilated façade of retractable shades and a “rainbow” concept with a gradually changing color palette subtly integrated within balustrade fins, giving the tower a refreshing identity within the hazy environs of the city. All options however were secondary to maintaining expansive views—the major selling point. Conceptual alternatives involved accentuating the twist both in its vertical manifestation as well as in the horizontal and oblique directions perceived from various strategic vantage points in the city. At 355 meters, the tower is certainly not the city’s tallest (World One at 450 meters, currently under construction is expected to be the tallest) but it is in the top three. Furthermore its presence and height is accentuated due to its hilly location. In addition, each unit is flanked by spacious decks, some as deep as 6 meters, to facilitate the indoor-outdoor lifestyle—although, given high winds and humidity, their use is questionable except for the short winter between December and February, when the temperature dips to a “freezing” 70° F.

Structural Anomalies

Structural integrity was one of the prime considerations for this sinuous tower, cantilevering out and receding within by approximately 0.75m (2’6”) at every floor and

Figure 5. Option 1 “Less is More” (Source: CallisonRTKL)图5. 方案一“少即是多”（来源：CallisonRTKL）

Figure 6. Option 2 “Exoskeletal” (Source: CallisonRTKL)图6. 方案二“外露结构”（来源：CallisonRTKL）

Figure 7. Option 3 “Nautica” (Source: CallisonRTKL)图7. 方案三 “海洋”（来源：CallisonRTKL）

的地势使它在周边环境中显得鹤立鸡群，它拥有一个八层的停车平台，楼高接近400米。它底部为直线型设计，有一个中央直线型核心筒，大楼两端鼓起再缩进，创造出一种蜿蜒起伏的造型，大楼高355米，在城市不断发展的天际线上显得居高临下，威风凛凛（图3）。

这座180个单元（有三居室或四居室，并带有环绕式露台），70层、355米高的大楼能供应约155000平方米的空间（即1660000平方英尺），加上1000个车位的停车库。它的独特的平面部局，约2000平方米（即21500平方英尺），呈拉长的矩形，角落则呈喇叭形。四个单元（三居或四居）跨立在四个角落，固定在核心筒上，塔楼有12个乘客电梯（电梯速度为每秒6米），除安全楼梯和管井外，另有两个服务电梯。大楼核心墙粗细不同，在大楼下层区域厚度为1000毫米，到大楼高层区域则为450毫米。核心筒的大部分长条是有空隙的，随着楼身向上向外倾斜，再逐渐向上向内缩进，使大楼拥有独一无二的外观。四个由三部分组成的单元和两个半层楼高三层豪华公寓立在建筑顶部，并直达顶端30米高的塔冠（图4）。

CallisonRTKL在该建筑事先确定的波状正弦曲线设计的基础上，为提升大楼美观程度，提出多个备选方案，旨在为大楼设计出与众不同的优雅外观（图5、6、7）。这些方案包括了密斯的“少就是多”的极简理念，去除所有外在的装饰，还有结构上极具表现力的骨骼结构，最后还参考了航海因素，暗喻波浪和船帆，契合孟买的航海历史和地理位置。其他设计构思还包括带可伸缩遮阳设计的立面，以及“彩虹”构思，即将逐渐变化颜色的调色板巧妙地融入栏杆翅片当中，让这座大楼成为这个城市雾蒙蒙地周围环境中的一抹亮色。所有的选择都应排在保持广阔的视野之后，这才是大楼的主要卖点。构思备选方案还包括强调大楼在垂直、水平和倾斜方向的扭曲程度，以便在城市各个战略有利位置观赏大楼。这座大楼高335米，显

Figure 4. Tower typical floor plan (Source: CallisonRTKL)图4. 塔楼标准平面（来源：CallisonRTKL）



collectively cantilevering and recessing a not insubstantial 18 meters (60’). Various structural framing options were investigated and special care was given to how the undulating profile was to be achieved. After numerous iterations, it was agreed that the optimum methodology was to have the structural columns reconcile with and follow the angle of the tower’s profile in continuous pours rather than progressive offsets on every floor (Figure 8).

As is always the case in most of Asia, concrete was the preferred option and conventional beam and slab configuration was deemed most appropriate for the structural framing. A beam and slab construction offered the best advantages although flat plate and PT slabs were carefully evaluated. Typical beam depths of 750mm (2’ 8”) for longer spans and slabs of 200mm (8”) were implemented and a dropped drywall ceiling ensured a 3m (9’9”)

clear height at the typical floors. The central linear core integrated “voids” as the tower undulated up to 70 floors, each at 4.2 meters (13’10”) in height. Initial concepts envisioned massive corner columns (1.5m x 5 meters) that would take the thrust of the major bending forces as the tower undulated. However, these were deemed to be highly undesirable from the perspective of unimpeded views and after several iterations the column sizes were reduced to a more manageable 3 meters x 1.2 meters. The stiffness of the concrete construction also obviated the need for any damping systems for a tower of this height. Preliminary wind tunnel desktop analysis validated the structural design concepts in terms of damping needs (none required) and acceptable frequencies of movement (Figure 9).

Foundation systems were designed as friction piles to the bedrock which was

然不是孟买最高的建筑物，但它必定名列前三。（World One, 孟买最高的建筑高450米，目前正在施工当中。）同时，它所处的丘陵地段也突出了它的存在感，强调了它的高度。此外，每个单元的两侧都是宽敞的露天平台，一些有六米深，用来方便人们室内室外的生活方式。然而考虑到强风和湿度，这些露台很不实用，除非是在12月到2月中间短暂的冬天，当温度下降到“冰冷的”70华氏摄氏度的这段时间，露台才能派上用场。

不寻常的结构系统

结构整体性是建造这座弯曲的大楼最主要的考量之一，悬臂梁每层伸出和凹进约0.75米（2英尺6英寸），总共伸出和凹进长度达18米（60英尺）。人们研究了很多结构框架备选方案，并重点关注如何实

Figure 8. Building Section (Source: CallisonRTKL)图8. 建筑剖面（来源：CallisonRTKL）

Figure 9. Structural section (Source: J+W Consultants LLP)图9. 结构剖面（来源：JW Consultants LLP）



available at a depth of less than 20 meters on the site’s hilly terrain. However, anything disturbing the existing contours of the site was deemed unacceptable by regulatory authorities. Therefore, tower was placed on several 4-meter deep rafts founded on (and following) the terrain’s contours and supported by 120 friction piles, each 20 meters long, reaching down to the rocky strata (Figure 10).

Several alternative structural design concepts were evaluated and discarded in favor of the time-tested concrete construction methodology further influenced by the SP Group, one of India’s two premiere construction companies and co-owner of the development. The exoskeleton design option was discarded on the basis that angular struts would block the desired views. Composite construction was also evaluated in order to reduce the amount of timely concrete delivery problems through the city’s clogged arterials

现大楼的波状外观。数次反复之后，大家认为最合适的方式是让架构柱保持与大楼外观的角度一致，然后持续浇筑而不是分层浇筑（图8）。

亚洲的许多塔楼建筑案例表明，人们最中意的选择是混凝土，而常规梁板结构对于结构框架来说是最合适的。尽管人们仔细评估了平板和后张板的可行性，梁板结构仍具有最大的优势。大楼采用的特有的长跨度的梁的高度为750毫米（2英尺8英寸），混凝土板的高度为200毫米（8英寸），并采用了石膏板吊顶，保证了从标准层向上3米（9英尺9英寸）的净高度。中央直线核心筒设计融合了“空隙”，使楼身可以以波状向上延伸至70楼，每层楼高4.2米（13英尺10英寸）。大楼最初的构思需要大量角柱（1.5米 x 5米），当塔楼呈波浪状起伏，可以承受主要的弯曲力产生的推力。然而，为了保证视野开阔，这些角柱似乎十分不理想，因此在几次反复推敲后，角柱尺寸降为3米 x 1.2米。混凝土施工的刚度也使这种高度的塔楼不再需要阻尼装置。初步的风洞桌面分析在阻尼需求（不需要）和可接受运动频率方面验证了结构设计构思（图9）。

大楼地基设计为用于岩层的摩擦桩，而丘陵地带地下不到20米处就有岩层。然而，监管机构不能接受任何改变现有地形的情况出现。因此大楼安置在多个4米深的、建于丘陵等高线上筏形基础上，由直达岩层的120根、长20米的摩擦桩支撑（图10）。

由于印度两家杰出建筑企业之一SP Group的影响（它同时也是开发项目的共同业主），很多备选结构设计构思经过评估都最终放弃了，最佳方案是久经考验的混凝土施工方案。外墙骨骼结构设计选项也被否定了，因为斜撑结构会阻挡人们的视野。人们也考虑过复合结构，可以减少由于城市交通堵塞而造成的混凝土配送不及时的问题，并将框架结构施工周期减少到7天或更少（这种情况下楼板施工周期为10到15天）。混凝土核心筒和边界柱，钢梁和金属平面楼盖都经过了评估，承包公司和CM顾问都仔细审核了最初设计。考虑到低廉的钢价，初步分析认为复合结构具有很高竞争力，并且节约成本，能缓解配送和抽水拖延的时间，减少负荷和地基成本。但是，考虑到混凝土体系的优势，以及缺少钢结构和安装熟练工人，这个选项最终还是被放弃了。其他选项则包括后张板，隧道模板和预先浇铸的混凝土主梁，但是所有选项都最终输给了常规体系，地方经验和舒适度（图11）。这些探索选项都清楚说明了，设计决策最主要取决于久经考验的偏好上，而不是其他经济上更具竞争力的选择。

Figure 10. Raft foundation (Source: JW Consultants LLP)图10. 阀式基础 (来源：JW Consultants LLP)

Figure 11. Composite framing option (Source: JW Consultants LLP)图11. 复合结构选项（来源：JW Consultants LLP）

and improve the framing schedule to a seven-day cycle or less (typical floor cycles in this context range from 10 to 15 days). A concrete core and perimeter columns, steel beams and metal deck flooring option was evaluated and contracting firms and CM consultants carefully vetted initial designs. Given low steel prices, preliminary analysis made the composite system highly competitive and cost effective, alleviating delays of delivery and pumping, reducing loads and foundation costs. Yet, given the preponderance of concrete systems and lack of sufficient skilled labor for steel fabrication and installation, this option was ultimately discarded. Other options explored were PT slabs, tunnel formwork and pre-cast concrete girders, but all options eventually lost to conventional systems, local experience and comfort levels (Figure 11). These exploratory options clearly define how design decisions were based on time tested preferences as opposed to other financially competitive options.



外墙系统选择

大楼的主要美观之处仍是由外围装有玻璃的阳台连接而成的动态之美。之前提到过，我们的构思概念集合了城市的地理特征和航海传统。城市上空一抹波状的造型，它既可以是灯塔，也可以是吸引眼球的城市象征。我们详细探索了各种覆盖材料和技术，得出几种选择包括玻璃纤维增强混凝土、高密度可丽耐材料、穿孔金属板和陶瓷熔块，作为栏杆立面和端壁的考虑。其他的选择则包括考虑用不锈钢翅片和二色性夹层箔材作为栏杆玻璃。我们简化了细节，以确保易于安装和气候防护，同时本地制造商提供了有竞争力的报价。最高点的钢架构灯笼片设计成多层和重叠的式样，就像是随风鼓动的船帆。塔身总体调色保持在白色和灰白色之间，在灰蒙蒙的城市上空营造出一种活泼轻快的、闪烁的质感（图12）。

动感蜿蜒的塔身对于建筑维修策略和系统将是非凡的挑战，尤其在隐私和安全问题上。塔楼围护系统顾问专门设计的方法包括了沿绳滑下法到普遍使用的擦窗机。

演变

在这篇论文的提交期间，塔楼设计将不断演变，演变方式难以预料，同时必须保持塔楼在充满竞争力的市场上卓尔不凡的特

Façade Options

The primary aesthetic of the tower remains as a dynamic form articulated by the wraparound glazed balconies. As mentioned earlier, the conceptual ideology is an amalgam of geographical and nautical references defining a sinuous form on the city’s skyline that is at once a beacon and an eye-catching icon. Various cladding materials and techniques were explored at length and several options were considered, ranging from GFRC, high density Corian, perforated metal and ceramic frits for the balustrade facades and end walls. Other options included the evaluation of stainless steel fins and dichroic inter-layer foils within the balustrade glass. Details were simplified to ensure easy installation and weather-proofing as well as competitive quoting by local fabricators who are generally skittish about quoting for highly detailed and performance driven criteria. The culminating steel-framed lantern piece was designed in layers and overlaps, metaphorically representing billowing sails. The general palette of the tower was retained in the white and off-white ranges, giving the structure a breezy and shimmering quality in the city’s notorious haze (Figure 12).

The dynamic and sinuous profile of the tower created extraordinary challenges for the building maintenance strategies and systems, specifically with regard to privacy and security issues. The building envelope consultants developed creative custom-designed methodologies including options ranging from abseilers to universal BMU tracks.

Evolutions

At the time of submittal of this paper, the design continues to evolve in many ways originally unanticipated, whilst maintaining the aim of the tower’s preeminence in this competitive market. This highlights the flexibility exhibited by the developers and owners of this project in the face of market demands and regulatory constraints. Primary reasons for this design evolution and modification range from an anticipated increase in FAR in 2016, overall cost control, construction time frames and floor plate efficiency. Changes in the political and regulatory structure also incentivized the client to modify the “approved” design to better meet market demands. Most critical in this reevaluation process was the reduction of the expansive decks that increased the sales price of the units, making them uncompetitive in an aggressive buyer’s market. Such market indicators made it imperative that the “product”

did not deviate too much from other available choices for prospective buyers and investors. The reduced floor plates also allowed for a few additional floors and units thereby positively contributing to a better financial pro-forma.

This led to current and ongoing explorations in “straightening” the tower (but still maintaining a relatively sinuous profile) and reducing the floor plate from the initial 37m x 83m to a more manageable 31m x 65m by eliminating the extraneous “voids” within the core and tightening up the expansive decks. The modification resulted in a tower profile with a more slender proportion, reduced overall area, better net to gross area efficiencies, reduction of excessive framing and formwork costs and an overall reductions of construction time frames and delivery schedules—thereby staying competitive in a soft market, especially as the inventory of similar luxury products in the market is expected to increase in the next few years.

New three-dimensional studies explore a sculptural form akin to a flower vase with a slight bulge in its mid-section and tapered profiles at the bottom and top, culminating in a striking crown feature. This simplification manifested into structural clarity, condensed construction schedules, easier building maintenance and minimalist, yet elegant detailing. Studies continue to be generated to

Figure 12. Façade studies (Source: CallisonRTKL)图12. 建筑立面研究（来源：CallisonRTKL）



结论

孟买这个城市很有可能是未来超高层建筑的集中所在地，但是可以预见的是，这些建筑不是商业办公楼也不会是综合体建筑。几乎所有的新的高层建筑都在住宅区，而建造豪华住宅大楼的趋势在未来20年将进一步扩大，而越来越多的购买力则来自高净值人士。超纤细塔楼将会是另一种趋势，尤其考虑到占用地块面积小，以及建筑上层面壁须逐渐收进。这一趋势和曼哈顿的”铅笔楼”颇为相似。帝国大厦3预计耗资3亿美元，顶楼豪华公寓售价约为150万美元一套，这与曼哈顿的豪华公寓售价相比不值一提，但在第三世界国家来看，肯定是十分高昂的。

今天，印度和中国（尽管前者经济好转，而后者经济动荡），在城市快速发展过程中面对的挑战和机遇是十分相似的。包括类似的地缘政治、社会经济、移民、金融和科技因素，人口膨胀和社会分层。两国当前都斥资数十亿美元发展“小型城市”，促进基础设施升级和推进城镇化进程，以解决孟买居民的需要和上海呈上升趋势的居民流动性带来的问题。我们从帝国大厦3个案开发所学到的教训，在变化的市场需求如何彻底地或在表面上影响这类建筑的设计和经济性上，同样适用。

evaluate the tower’s profile from key vantage points in the city and how it is perceived, both as a distinct silhouette from afar as well as from close proximity. Other explorations are under way to reduce the height and construction of the lantern and crown feature, partly in deference to the regulatory recommendations and partly to reduce the cost of non-revenue generating features. Additional enhancements include carefully engineered façade and cladding systems, integrated lighting systems, and landscape and interior design for the public areas to promote resort-style luxury. Ultimately, buyers of such prestigious properties focus more on the location, unit planning, expansive decks and views. The iconography of the tower is generally of less consequence to the sophisticated investors who actually prefer low-key anonymity rather than expressive exuberance.

Conclusion

Mumbai as a city will probably be the location of the next generation of supertall towers in the world, but predictably not in the commercial office or mixed-use category. Close to 100% of the new tall buildings fall into the residential sector, and the luxury residential trend is guaranteed to proliferate in the next two decades with the increased buying power of high net worth individuals. Ultra-slender towers are the next trend especially given extremely small plots of land and onerous setback conditions—a trend very similar to the current crop of “pencil” towers in Manhattan. Estimated to cost $300 million, the Imperial 3 penthouse apartments would fetch close to $15 million apiece—small-change compared to Manhattan prices, but certainly very high within third world contexts.

Today, both India and China (in spite of the current economic upturn in the former and turbulence in the latter), exhibit similar challenges and opportunities in their growth prospects within their rapidly evolving urban contexts. These include very comparable geo-political, socio-economic, migratory, financial and technology implications, burgeoning populations and social stratifications. Both economies are currently investing billions of dollars in “smart cities”, infrastructure upgrades and a rapid pace of urbanization for the denizens of Mumbai and the upwardly mobile citizenry of Shanghai. Lessons learnt from individual developments like Imperial 3 are also highly applicable in terms of how changing market demands radically or peripherally affect design and economics of such pursuits.

质。这就要求开发商和项目业主在面对市场需求和监管限制时做到灵活应对。塔楼设计不断演变和修改的主要原因在于2016年可预测的容积率的上调，总体成本控制，施工期限和楼面板利用率。政治因素和监管结构变量也刺激着委托商修改”已确认”的设计，从而更好的满足市场需求。这一轮再评估过程中最关键的改动是减少开阔的露台面积，从而增加了单元住房的销售价格，使它们在激烈的买房市场竞争力有所下降。鉴于这些市场指标，“产品”不能过分偏离市场上的其他选择，这样才能吸引潜在购买者和投资者。楼面板面积的减少，可以实现增加楼层和单元数量，从而有利于塔楼的财务状况。

所以，人们当前正在进行的探索就是“拉直”楼身（但仍保持相对弯曲的外观），通过去除核心筒内的不必要的“空隙”并且收缩露台面积，将楼面板从最初的37m x 83m减少到31m x 65m。这些改动让大楼外观更加苗条，减少了总面积，净面积利用效率更高，减少了过多的框架和模板成本，并缩短了总体施工时间和交付期限。这使它在市场疲软状态时，特别是在未来类似豪华产品数量有望上升的情况下，仍保持竞争力。

新的3D研究探索了将大楼外形塑造成花瓶的样式，中段稍稍突出，底部和顶部逐渐收窄，再向上攀升到醒目的皇冠顶端。这种简化使大楼结构清晰，压缩了施工进度，让大楼更易于维修，体现了极简主义和优雅的细部设计。我们还继续做了很多研究，来评估从城市有利位置来看，大楼外观会给我们带来什么样的感觉，包括从远处观看大楼的轮廓和从近处观赏大楼外观会有什么样的感觉。我们还在进行其他研究，来减少大楼皇冠型的灯顶的高度和施工，部分是因为监管部门的建议，部分是想减少非收入建筑特征的成本。其他的改进包括精心设计的大楼立面和围护体系，将照明系统和风景、内部装潢相结合，为公共区域营造度假村式的奢华氛围。对于买主来说，他们最终关注点还是在地理位置，单元规划，露台是否宽敞，视野好不好这些方面。一般来说，塔楼的艺术形象对于富有经验的投资者来说不是那么重要，比起夸张的表现手法，他们更中意不显山露水的低调。


changing market forces and their impacts on tall building ... · the win was short-lived as the...

Documents