该项目位于东京传统商务区港区西新桥的街角，是集业主办公室、住宅和租赁办公室于一体的整体重建项目。

东京的商业·商务区主要由中层租赁式大楼构成，而这些大楼如今相继迎来了重建时期。环顾地块周围，主干道上虎之门 Hills 等大型开发项目正在紧锣密鼓地进行中，后街上同等规模的建筑鳞次栉比，荒川大厦作为其中之一，长期以来随着业主的企业发展也为城市做出了贡献。我们希望在重建之际，通过重新审视建筑自身的潜力，打造出一座可为今后的城市增添魅力的建筑。

疏散楼梯外置的立体式外立面，除了具有成就结构，控制环境和保障安全的综合性功能外，还可作为向城市散发活力与生机的展示窗。

此外，立体式外立面支撑的内部空间形状规整易于使用，与外部间有适当的缓冲，形成了生动、富有魅力的办公空间。充分利用了所有建筑构成要素的荒川大厦，作为城市景观重要构成的中层建筑，展示了为城市作出新贡献的可能性。

▼建筑外观，General view©野田东德（雁光舍）

This is a project to rebuild the owner’s office and residence as well as office space for rent on a street corner of Nishi-Shimbashi, Minato-ku, Tokyo’s historic business district. Many of the mid-story rental buildings, which occupy the majority of Tokyo’s commercial and business districts, are now facing rebuilding time. While there are large development projects like Toranomon Hills along the main streets near the site, buildings of similar size can be found along the back streets. ARAKAWA Bldg. has long contributed to its surrounding cityscape, along with the growth of the owner’s business. In its rebuilding, focus was placed on creating a building that would shape an attractive cityscape for the future by revisiting the potential of the building.

The sculpted and modulated façade that exposes the emergency stairs plays a complex role in shaping the building’s structure, controlling the environment, and contributing to safety. Meanwhile, it also provides an interaction between the city and the internal activities revealed on the surface.

The space supported within this façade is a regular shaped space and is easy to use. As a result, it becomes an attractive workspace with an appropriate buffer from the outside. The ARAKAWA Bldg. utilized the full potential of all building elements, while showing new prospects how a mid-rise building, which is an essential element of any cityscape, can contribute to the city.

▼疏散楼梯和阳台构成立体结构 The emergency stairs and balconies create a dynamic building volume©野田东德（雁光舍）

许多建筑与城市的联系仅限于配置有商业设施的一层部分，二层以上则用统一的外立面与外界隔断，结果往往就是形成了毫无特色的城市景观。对此，在荒川大厦项目中，我们将建筑构成要素之一的疏散楼梯作为所有楼层与外部的缓冲空间，通过在外延上设置类似于缘侧一样的空间，将人们的日常活动展示给外界，通过自然的连接赋予城市新的魅力。

▼设计示意，Diagram©日建设计

▼功能分布，Function – Section©日建设计

In many buildings, the connection to the city is limited to the ground floor where most commercial facilities are located. On the other hand, spaces above the 2nd floor are completely cut off from the outside by the stereotypical façade. As a result, a characterless cityscape is created. To address this, all levels of the ARAKAWA Bldg. are wrapped by emergency stairs, which are not only essential functional elements, but also work as an “engawa”-like space (veranda), as well as a buffer from the outside. The idea behind this was to create a new presence that reveals the activities of people within the building and, while adding attraction to the cityscape through its loosely woven relationship with its surroundings.

▼疏散楼梯作为所有楼层与外部的缓冲空间 Emergency stairs work as a buffer from the outside©野田东德（雁光舍）

▼缘侧一样的空间将人们的日常活动展示给外界 ©小林真梨子 The“engawa”-like space (veranda) reveals the activities of people within the building

东、南两侧由于道路间距制约，高度受到严格限制，大约 8 层开始这两侧必须向内缩进，屋顶机械设备设置处也受到一定限制。另一方面，由于设置疏散楼梯而形成的凹凸体量，通过有效利用天空率制度（天空率（%）=圆面积（Sa）- 建筑投影面积（Sb）/圆面积（Sa）），使建筑从 8 层增加到了 9 层，实现了建筑体量的最大化。看似低效率的外观，实际上却能够“最大程度地确保易于使用的空间”，对于办公楼而言是尤为重要的。

▼天空率概念图，Concept Diagram of Sky Factor©日建设计

The south and east sides of the building are subject to a strict height restrictions and setbacks above the 8th floor, peculiar to urban areas in Japan, established to ensure sunshine and daylight in living environments that face narrow streets. However, due to the sculptural building volume shaped by the configuration of the emergency stairs, sufficient lighting was secured for the surrounding environment, allowing the building to increase its height from 8 to 9 stories, maximizing the development volume. Even though the building may look inefficient in appearance, the shape actually contributes to “securing maximum usable space”, which is the most important benefit for office users.

在中层办公楼的内部空间中，包含厨厕等在内的核心筒一般约占平面形状的 1/4 左右。如果像以往一样将疏散楼梯集中配置到一处，即使能够最大程度地确保楼层面积，但由此切出的不规则平面往往不便于使用。通过将疏散楼梯外置于东南两侧的外立面，可以在不规则的外观中实现形状规整且易于使用的平面。

▼楼层平面图，Floor Plans©日建设计

Generally speaking, around a quarter of the planar shape of the interior space of a mid-story office building is occupied by the building core. If the emergency stairs were concentrated in one location in the conventional way, larger floor areas could be secured at the cost of irregular shaped floor spaces which tend to be difficult to use in many cases. On the other hand, by exposing the emergency stairs to the south and east façades, it enables a user-friendly regular shaped space inside the irregular shaped exterior.

▼6F 总部楼层，6F Main Office Floor©野田东德（雁光舍）

为了在有诸多制约的地块内实现合理的设计，我们将构成建筑的所有要素作为结构体加以利用，采用了硬壳式（monocoque）的三维结构。针对形状各异的各层平面，通过在平面延伸的方向上使用扁平梁以避免空间被结构件分割。由于各层扁平梁的配置不同，为此在东南角上采用了三维变形的外露式“图腾柱”，从而在较低的层高条件下实现内部空间的最大化。通过利用通常与结构无关的非承重墙和楼梯等作为抗震要素和支撑部位，在实现形状规整易于使用的室内空间最大化的同时，还打造了充裕的缘侧空间。▼FEM 模型，FEM Model ©日建设计

▼横梁和图腾柱示意，Diagram©日建设计

In order to rationally construct a building on a site with many restrictions, all building components were utilized as structural elements.

With a different footprint shape for each floor of the building, a flat beam system was applied to span the long axis of the space to avoid structural members dividing the space. Since the position of the flat beams vary on each level, the column at the southeast corner transforms in shape according to the location of the connecting flat beams. This helped to maximize the interior space while reducing floor to floor height. The column is exposed internally and as it takes on a different expression on each floor, it is referred to as a “totem pole” column. Miscellaneous walls and stairs, which are typically non-structural in conventional buildings, here act as seismic or bracing members to maximize the user-friendly regular shaped interior spaces, as well as to create a livery “engawa” space.

▼3F 租赁楼层，Rental Space Floor©野田东德（雁光舍）

▼对标志性的图腾柱不做装饰，直接外露于所有楼层，对空间起到了点缀作用©野田东德（雁光舍）Exposed and unfinished“Totem pole”column as a feature in the interior spaces on every floor level

为确保空间的开阔，6～8 层的业主办公楼层直接采用结构混凝土作为天花板，结合市售成品新开发了一种可以照亮整个天花板的上下配光型线性照明系统。由于该系统无需定制，只需将现成的照明器具结合部件即可构成，所以即使发生故障也仅需更换相应部件即可。

租赁办公室（2～5 层）虽然设有天花板，但通过将线性照明灯具直接安装在天花板上，可与高楼层一样确保天花板面的明亮度。

吊灯照明的构成，Suspended Ceiling Light Fixture©日建设计

To help the office spaces feel more spacious, the exposed concrete ceilings of the owner’s office floors (6F~8F) are illuminated utilizing a new linear system developed by combining ready-made uplight and downlight components to make the entire ceiling look bright. Through the combination of existing fixtures and components rather than a custom-made fixture, repair and maintenance is facilitated by simply replacing failed components.

For the rental office floors (2F~5F), suspended ceilings are provided; however, the linear lighting fixtures are mounted directly on the ceiling providing a bright surface a similar way as the upper floors.

▼7F 总部楼层，7F Main Office Floor©野田东德（雁光舍）

▼8F 总部楼层，8F Main Office Floor ©小林真梨子

疏散楼梯和阳台构成的立体结构，可为下层的开口空间遮挡日晒。通过控制阳光直射，即使没有百叶窗也可以使柔和的自然光从小开口处照进室内。此外，从不同开口处所眺望的景色，彷如一幅幅的风景画让人对外部心生向往，同时还会联想到各层与城市的不同关联，感受与城市张弛有度的闲逸连接。

根据建筑标准法，疏散楼梯 2m 范围内只能设置 1㎡以内的固定式（不可开关）防火窗。考虑到紧急出入口（备用出入口）和结构设计对承重墙的限制，我们设计了一种可在最大程度上确保可利用窗的方案。

The dynamic building volume created by the emergency stairs and balconies provides a shading effect to the openings of the floors below. As a result, indirect natural light enters through the small openings without the requirement for blinds. In addition, the framed views provided by the small openings evoke a sense of anticipation toward the outside world, like looking at a piece of artwork. At the same time, the different views and a different sense of connection to the city on each floor will create an awareness of being loosely woven into the whole cityscape.

In compliance with the Japanese Building Standards Act, only fire-rated fixed windows of maximum 1 sq m in size are applicable within 2m of the emergency stairs. Also, consideration of the rescue entrance (alternative entrance) as well as restrictions on load-bearing walls for structural design was required to secure the maximum number of effectively usable windows.

柔和的自然光从小开口处照进室内，Indirect natural light enters through the small openings ©小林真梨子

今后，东京的许多建筑将迎来重建热潮。在各个建筑逐步探寻如何面对城市，融于城市的挑战过程中，势必将会产生更多丰富多彩、更具魅力的城市提案。无关规模大小，“实现租赁面积的最大化・最优化和保证疏散安全”是许多办公楼面临的课题。而对于与当地关系紧密的建筑而言，另一个课题则是“如何与城市建立积极的多元化联系”。荒川大厦通过硬壳式“建筑形式”解决了这两个课题。开放式楼梯成为人们的休息场所，作为与城市间的界面赋予城市新的风景。充分利用有限的建筑构成要素，使使用者的活动本身也作为建筑的外立面得以展示。我们希望以这种形式打造的动感外立面可以赋予城市新的面貌。

There are many buildings in Tokyo nearing the end of their commercial life and requiring rebuilding. We believe that if each building focuses on its relationship with its surroundings, this could potentially lead to a more attractive and lively city. Regardless of size, many buildings must address “the balance of maximum and optimal rentable floor area and safety for emergencies.” They must also address “diverse and active ways of engaging with the city,” as unique buildings that are closely linked to the local community.

ARAKAWA Bldg. has solved both of these issues by the proposed “shape of the building” and its innovative approach to structure. The exposed external stairs become a place for relaxation as well as adding new expression as an interface with the city. The building has utilized the full potential of every building element, and now reveals the activities of the building users as an element of the building’s façade. Our intention is that the dynamic façade incorporating human activities would also create a new expression in the cityscape.

开放式楼梯作为与城市间的界面赋予城市新的风景 The exposed external stairs add a new expression as an interface with the city©野田东德（雁光舍）

▼荒川大厦夜景，ARAKAWA Bldg. night view©野田东德（雁光舍）

▼5F 平面图，5F plan©日建设计

立面图，Elevations©日建设计

▼剖面详图，Detailed Section©日建设计

项目名称：荒川大厦项目位置：东京都港区项目业主：（株）ARAUN 主要用途：办公室、商铺、住宅设计・监理：日建设计项目施工建筑：（株）不二工务店电气：（株）INAZUMA 电气工事空调卫生：芳野工业（株）用地面积：139.51㎡占地面积：123.02㎡建筑面积：824.81㎡建筑层数：地上 9 层、设备层 1 层檐口高度：29.9m 最高高度：35.1m 建筑结构：钢筋混凝土结构设计期间：2015.2～2016.11 施工期间：2016.12～2018.3

Building Overview Name: ARAKAWA Bldg.

Address: Minato-ku, Tokyo

Client: Araun.Co,Ltd.

Building Use: Office / Commercial / Residence

Design / Supervision: Nikken Sekkei Ltd

Construction Building Contractor: Fuji Koumuten

Site Area: 139.51㎡Building Area: 123.02㎡

Total Floor Area: 824.81㎡

Number of Stories: 9 Stories above ground, Rooftop elevator tower 1 Story

Eave Height: 29.9m

Maximum Building Height: 35.1m

Structure: Reinforced Concrete Structure