许多快速发展的东南亚城市的扩张, 都伴随着混凝土、钢铁和其他不可再生材料的大量消耗。然而, 现代社会越来越受到物质资源稀缺的挑战。近年来, 随着新型制造和建造方法的发明, 木材重新成为一种有吸引力的建筑材料替代品, 有着多样的潜力, 不仅可以作为结构材料, 也可以作为建筑表皮。最重要的是, 木材是一种可再生材料, 与最常用的建筑材料相比, 其对环境的影响要小得多^[1]。除此之外, 木材还有着高度的可预制性和相当低的重量。

　　 实际上, 木材工业在东南亚有着悠久的历史。就像世界上许多其他地区一样, 木材曾经是建造中使用的主要材料, 并且作为丰富的资源可供使用。随着混凝土和钢铁等现代建筑材料的发展, 以及这些材料所具有的生产高效和性能一致等明显优势, 木材工业逐渐衰退并最终消失。直到最近, 胶合层压木材 (Glulam) 和交叉层压木材 (CLT) 等材料系统才在东南亚地区受到关注, 因其具有很好的技术特性, 并同样具有材料的一致性, 未来可能为振兴热带地区的木结构建造铺平道路。

　　 本文讨论的一系列设计实验是新加坡科技设计大学设计工作室的成果, 实验重点是木构节点和装配技术的构造方式和形式变化。受到“振兴已经从城市建设中消失的休眠工业部门”的概念启发, 材料实验被视为一个开始。木材、复合材料和混合建筑系统成为了探索的焦点, 以设想垂直建造的新概念。此外, 实验的灵感来自于热带建造技术, 如在印度尼西亚发现的藤条木材与木质节点的搭接, 或苏门答腊长屋的织物般的轻质编织木结构 (图1) 。

　　 本研究是在数个先行研究的框架下展开, 开始的探索对实验和材料特性在设计中的体现有着同等的重视, 如同斯图加特大学计算设计学院 (ICD) 所建造的许多全尺度展馆中体现的一样^[2]。在这项设计研究中, 数字制造技术仅作为快速设计迭代和理解木材实际物理性能的手段。这项研究更侧重于建筑设计方面, 并试图预测木质建筑构件的大规模应用。因此, 它也不太重视高精度^[3]或对潜在加工过程的重大改变^[4]。在巴特莱建筑学院的研究集群^[5]中可以找到更为详细的参考资料, 其中包含复杂结构体系中离散元素的装配策略^[6]。

　　 工作室专注于跨平台的设计实验, 强调将制造实验与Rhino 3D和Grasshopper插件中发现的参数化方法相结合。因此, 它建立在“建筑学的第二次数字化”^[7]的概念之上, 在这一概念中建筑设计不再需要被压缩成二维和简化的线条图纸, 而是利用数据表现来推进复杂的装配逻辑。此外, 学术界的注意力从类型学转向拓扑关系^[8], 远离高度特异性和单一功能的类型 (类型学) , 这些类型以简单重复的方式拓展, 转向可以进行参数化变化并可针对不同条件进行优化的拓扑组件。这导致对建筑构造节点的重新关注, 表达了结构系统和材料节点的设计细节 (图2) 。

　　 12个设计实验根据基本元素的几何参数及其节点拓扑关系进行了分类:首先是线性 (L) 、平面 (P) 元素和曲线 (C) 形状;然后是正交 (O) 、三维 (3) 和过渡 (T) 关节;第三点是纤维或纺织品 (F) 与木材的材料组合。进一步解释三个实际项目, 以详细说明其设计阶段和建筑理论方面的研究。在初始设计阶段, 构造实验探索的是线性承重元件 (如梁、柱) 和表面元素 (如墙、板) , 以及如何将表皮与线性元件同更薄的表面元素相结合。通过关注各种几何形式和建立构造系统, 所有实验都从构造现实中抽象出来。实验所用到的实体原型是由贴面板、胶合板和木板建造的。

　　 这一模式对于材料探索阶段是示例性的。在这种情况下, 使用不同切割方式创造的切口被策略性地用于软化木材, 使其弯曲并在过渡节点处连接。木质元件在这样处理后会失去其张力, 但仍保留一些主动弯曲性能和大部分抗压性能。为了恢复拉伸强度, 在表面切割切口之后围绕弯曲节点编织纺织纤维以引导纤维。编织木材接缝的概念与印尼传统房屋中的本土连接技术相对应。各种弯曲角度、分叉和交叉点都经过了测试, 未来的实验还将考虑木材元素的晶粒方向, 并在已建立的复合材料系统内形成更加优化的内部结构。另一个不同的项目还探索了织物编织作为结构稳定机制的替代方案, 即通过应用互锁楔块来稳定构件曲率 (图3) 。

　　 在工作室的第二阶段, 设计概念被分类以评估组件的性能并构建建筑构件目录。这些构件适用于各种尺度和功能, 并通过参数化方式变化和区分, 以满足建筑项目的不同标准。构件目录包括可用空间、屋顶、墙壁, 同时墙壁又包括穿孔系统、循环系统等。

　　 在项目LPT模式中, 实验关注点转向对层压板贴面和过渡关节的探索。构件之间的连接点从角落向构件的直线部分移动, 这使得关节本身不受几何约束的影响, 并且可以实现从水平方向到垂直方向的力的连续平移以及从线性到平面元素的逐渐过渡 (图4) 。

　　 最终, 上述所有的模式都被转译成建造项目。我们选取了10层以下的小型高层建筑的建造为案例研究的内容, 建筑的底面积在 (6~8) m× (10~12) m之间。微型塔楼位于新加坡, 坐落在一排传统商店建筑后面, 参与者可以探索其形式系统连接不同类型城市环境的能力。系统在第二阶段的基础上进一步完善, 以便清晰地表达承重、循环、包络和分隔系统 (图5) 。

　　 如图6所示:

　　 (1) LOJ——线性元素, 正交节点:通过正交节点和轴向距离的变化实现复杂性。

　　 (2) L3J——线性元素, 三维节点:线性元素在三维空间中进行连接, 以增加结构系统的侧向稳定性。

　　 (3) COJ——曲线元素, 正交节点:这种设计将经过优化的力流模式转化为结构系统的节点, 然而在弯曲元件之间建立连接系统以及创造有意义的组织逻辑依然比较困难。

　　 如图7所示:

　　 (1) CCJ——曲线元素, 曲线节点:这一模式着重探索木材构件切口的切割方式和曲线构件的布置策略。

　　 (2) P3A——平面元件, 三维组装:诸如交叉层积材 (CLT) 面板的平面元件被用于建立具有横向稳定性的三维结构。

　　 (3) SFJ——薄板元件, 纤维/纺织节点:这一座塔楼的独特性源于其中轻质网格状元件的组合, 这些元件与织物膜结合以提供抗拉强度。

　　 本次研究在记录材料与工艺, 了解木构建筑工艺悠久的历史, 重新概念化并将研究结果投射到新的形式概念中这些方面取得了成功。超越胶合层压木材 (Glulam) 和交叉层压木材 (CLT) 等技术的尝试, 使其成为更关键的设计论述的一部分, 试图从木材的检验和设计中获得额外的审美价值。这超出了普遍讨论的低生态影响、高度预制化和低自重的范畴。

　　 因此, 实验试图提供热带环境中木构建造的新观点。目前, 由于建筑认证许可, 世界各地为数不多的新建木建筑大多使用欧洲软木制成的构件, 而热带硬木并没有太多的记录和测试。但热带硬木将为大规模工程木材 (MET) 提供巨大的应用机会, 因为典型的热带硬木密度是欧洲软木密度 (700~900kg/m³) 的大约两倍, 具有更加优异的承载能力。与现有技术相比, 这将促生出更加纤细且使用不同节点的木结构系统。总之, 对于使用热带硬木的木构建筑以及针对性应对热带气候的更具体的工程和设计, 还有很多的研究机会, 因为目前这一领域几乎没有研究成果存在。

　　 Many of the fastest growing cities in Southeast Asia have expanded with massive consumption of concrete, steel and other non-renewable materials.However, society is increasingly challenged by a scarcity of material resources.Recently, wood has resurfaced as an attractive alternative with the invention of new manufacturing and construction methods.It offers manifold potentials, as structural material as much as for envelopes.On top of that, wood is a renewable material and has a significantly lower impact on the environment than the most commonly used construction materials (Gustavsson, 2006) .Further added benefits are a high degree of pre-manufacturability and considerably lower weight.

　　 The timber industries actually look back on a long history in Southeast Asia.Just like in many other regions around the world, wood once was the predominant material used in construction and was available as an abundant resource.With the advancement of modern construction materials such as concrete and steel though, and their apparent advantages such as efficient production processes and consistent properties, the timber industries went into decline and eventually vanished.Only very recently, systems such as Glue Laminated Timber (Glulam) and Cross Laminated Timber (CLT) have received attention in the region as they offer competitive technologies with equally consistent material properties.They potentially pave the way for a revitalisation of wood construction in tropical regions.

　　 These series of design experiments discussed in this paper are the results of a design studio at Singapore University of Technology and Design.The focus is set on the tectonic articulation and formal variation of wood joinery and assembly techniques.Material experimentation is taken as a point of departure, inspired by the notion of revitalising a dormant industry sector that has disappeared from urban construction.Wood as well as composite materials and hybrid construction systems are explored to envision new concepts of vertical construction.Additionally, inspiration is taken from tropical building techniques like the tying of timber joints with Rattan wood found across Indonesia, or the lightweight and fabric like woven wood structures of Sumatra Long Houses.

　　 The studio initiates its explorations with similar emphasis on physical experiments and translations of material properties into design as has been demonstrated in numerous full-scale pavilions at ICD Stuttgart (Fleischmann, 2012) .This design research uses digital fabrication technologies merely as means of quick design iterations and for the comprehension of the actual physical behaviour of wood.It rather focuses on construction design aspects and tries to anticipate large-scale applications of building components.Hence, it also puts less emphasis on high precision (Sass, 2006) or the large variation of potential machining processes (Willmann, 2016) .A closer reference can be found at the Bartlett School of Architecture’s Research Cluster 4 with assembly strategies for discrete elements in intricate configurations (Retsin, 2017) .

　　 The studio focuses on design experiments across different media.It emphasises fabrication experiments paired with the parametrisation of the findings from physical models Rhino 3D modelling software and the Grasshopper plugin.It thus builds on the notion of the“second digital turn in architecture” (Carpo, 2017) , where architectural designs no longer have to be compressed into two-dimensional and simplified line drawings, but instead utilise data representations to bring complex assembly logics forward.Also, the attentions shifts from typologies to topologies (Schumacher, 2008) –away from highly specific and mono-functional types (typology) that are reproduced in a mode of simple repetition towards topological components that can be parametrically varied and optimised to different conditions.This results in a renewed focus on the tectonic articulation of architecture, expressing the structural systems and the construction design details of material joints.

　　 The 12 design experiments are categorised according to geometric parameters of their basic elements, and the topologies of their joints:firstly, linear (L) , planar (P) elements and curvilinear (C) shapes;secondly, orthogonal (O) , 3dimensional (3) and transitional (T) joints;and thirdly, material combinations of fibres or textiles (F) with wood.Three projects are further explained to elaborate the design phases and architectural studies.In the initial design phase, physical experiments started exploring linear load bearing elements (such as beams and columns) , surface elements (such as walls and slabs) , and correlating skins with“thinner”versions of linear and surface elements.All experiments were abstracted from the construction reality by focusing on various geometric formations and establishing tectonic systems.Physical prototypes were built with veneer, plywood sheets and timber planks.

　　 This concept is exemplary for the phase of material explorations.In this case, kerfing was used to strategically soften the wood with different cutting patterns, bending it and connecting in transitional joints.The wood elements lose their tension capacity but retain some active bending behaviour and most of their compression resistance.In order to regain tensile strength, textile fibres are woven around the bent nodes following the incisions in the surface to guide the fibres.The concept of weaving timber joints is paralleled by vernacular joining techniques in Indonesian houses.Various bending angles, bifurcations and intersections were tested;future experiments will additionally take the grain direction of the wood elements in consideration and form optimised correlations within the established composite material system.An alternative to textile weaving as a stabilising mechanism was explored in a different project by applying interlocking wedges to stabilise the curvatures.

　　 In the second phase of the studio the design concepts were categorized to evaluate the capacities of the physical components and to build a catalogue of architectural elements.These elements were adapted to various scales and functions:they were parametrically varied and differentiated in order to meet different criteria of an architectural programme.The catalogues included usable spaces, roofs, walls including perforation systems, circulation systems and so on.In the project LPT, the centre of attentions was shifted towards the lamination of veneer and the exploration of transitional joints.The joining point between elements is shifted from the corner towards the straight sections of elements.This liberates the joint itself from geometric constraints and enables continuous translations of forces from horizontal to vertical directions and gradual transitions from linear to planar elements.3.3 MICRO-TOWERS

　　 Eventually all concepts were translated into architectural programs.The development of small high-rise buildings of up to ten stories high, and with footprints of around six to eight by ten to twelve metres served as case studies.These Micro-Towers are located behind a row of traditional shop houses in Singapore, allowing the participants to explore the capacity of their formal systems to connect to different types of urban context.Systems were further refined from phase two in order to articulate load bearing, circulation, envelope, and partition systems:

　　 ·LOJ-Linear Elements, Orthogonal Joints:complexity is achieved with orthogonal joints and the variation of axial distances.

　　 ·L3J-Linear Elements, 3-dimensional Joints:linear elements are joined 3-dimensionally in order to increase lateral stability in the structural system.

　　 ·COJ-Curvilinear Elements, Orthogonal Joints:this design translates an optimised pattern of force flows into the articulation of the structural system.Difficulties occur particularly in the joining system between curved elements and in establishing a meaningful organizational logic.

　　 ·CCJ-Curvilinear Elements, Curved Joints:this concept explores kerfing of wood members and strategical placement of curvilinear members.

　　 ·P3A-Planar Elements, 3dimensional Assembly:planar elements such as CLT panels are used to establish a three-dimensional structure with lateral stability.

　　 ·SFJ-Sheet Elements, Fibrous/Textile Joints:the unique character of this tower results from the combination of light weight grid like elements that are combined with textile membranes in order to establish tensile strength

　　 Since wood has been off the attention in urban construction, the seminar proved successful in recording the material and craft to get a sense of its long history, re-conceptualising it and projecting the findings into new formal concepts.The attempt to go beyond technologies like Glulam and CLT makes it part of a more critical design discourse that attempts to get an added aesthetic value from the examination and designing with timber.This goes beyond the commonly discussed benefits of a low ecological impact paired with high degrees of pre-manufacturing and considerably lower weight.

　　 It thus tries to provide a fresh view on timber construction in a tropical context.Currently, due to building certifications, elements made from European softwoods are shipped across half the globe for the few newly constructed timber buildings.Tropical hardwoods are not much documented and tested, although they would offer huge opportunities for applications as Mass Engineered Timber (MET) :typical species have around two times of the density (700-900 kg/m3) and thus superior load bearing capacities.This leads to slenderer and differently articulated wood construction systems than current technologies.In conclusion, there is a lot of research opportunities for timber construction with tropical hardwoods and for more specific engineering and design for tropical climates as it hardly exists now.