StructureTalks找形的意义
Motivation / 动机虚拟防火墙For our structures we always aim for an optimal solution combining various often contradictory aspects. During the design process structural, functional and aesthetical requirements need to be considered. The priorities may vary for each project, but the objective is always a holistic approach - a `symbiosis´ of all criteria.While finding an optimum for each system two main items should be considered as they have a significant influence on the structure’s performance: force and geometry. At sbp we therefore developed veral approaches for a form finding process to achieve the best possible solution for each project.
During the form-finding process the top priority is identifying the geometry that enables the optimum force flow within the structure. During the further development of this geometry the focus shifts towards aesthetic and constructional aspects. The boundaries between the two approaches are often blurred.
结构设计中我们总是在各种矛盾的因素之间寻求最优方案，结构、功能、美学需求一个都不
能少，但是应该优先考虑哪一项呢？当然不同的项目有不同的答案，但目的都是要找到一个综合各项指标的最优的结构方案。
在寻找最优结构方案的过程中，有两个因素对结构性会有重大影响：内力分布和几何形状。sbp施莱希公司研究不同的找形方法，力图为每个项目找到最优的结构方案。
美食介绍
在找形中，首先必须明确如何的几何形状能够在结构中实现最优的力传导；得到几何形状后的完善阶段，工作的焦点又会转移到形体和构造方面；然而这两个阶段之间的界限经常是模糊的。
Form-Finding for optimal force flow / 通过找形实现最优的力传导
When designing resource-saving structures, the key objective is to optimize the material usage. A material-efficient construction can be achieved by optimizing the force flow with mainly 2 simple guidelines:工科专业
设计一个高效的结构，关键是要优化结构材料的用量。通过优化结构受力则可以提高材料的利用率，这个过程主要遵循以下两个简单的指导原则：
- Bending moments should be avoided / 避免弯矩
The forces are distributed evenly over the cross-ction. Therefore, the full capacity of the material cannot be ud.
力在构建横截面上是均匀分布的，这样材料才可能达到100%的利用率。
- Tensile forces transfer loads more efficiently than compressive forces. / 拉力比压力传递荷载更高效
The reason for this is the destabilizing effect of compresd components. This phenomenon is easy to understand by imagining a simple ruler under load.
原因就是受压杆件会有失稳的可能。我们可以想象一下一把尺子在受压时的状态，便很容易理解这种现象。
To create a material efficient system, we always try to keep tho in mind as they are timeless. This leads to amazing structures such as light-weight cable net or membrane roofs.
喝中药能喝酒吗
谨记上述原则是设计高效的结构体系的前提，如下图示例，轻型索网结构体系和膜结构体系同样遵循了上述原则。
微信申请账号▲ Roof over the Olympia stadium in Munich, Germany (1972) / 1972年德国慕尼黑奥林匹克体育场屋盖 © Michael Zimmerman / sbpAlso, astonishing but nevertheless efficient structures like cable suspended footbridges are possible.
形态动人同时又高效的结构体系也是可能实现的。悬索桥便是其中一类案例。关于月亮的手抄报
▲ Erzbahnschwinge Bochum, Germany (2003) / 德国波鸿人行桥 © Tomas Riehle▲Footbridge Gelnkirchen, Germany (2009) / 德国盖尔森基兴人行桥 © Michael Zimmerman / sbpBut as few construction projects can be realized using only tensile structures, even the most efficient structures, such as cable nets and membranes, require compression members. Conquently, the best structure for standard construction projects is an intelligent combination of axially compresd and tensile-loaded members.sbp developed a tool which allows to combine tensile elements with elements under compression as well as bending when necessary. It enables the efficient
analysis of different design options considering varying design parameters. In combination with innovative design approaches it allows us to develop unusual structural designs all the way to detailed design and construction.虽然拉力比压力传递荷载更高效，但很少有项目是仅靠拉力体系就能实现的，即使是最高效的结构如索网和膜结构体系，受压杆件也必不可少。所以，对于大多数的项目，最佳的结构方案是将轴向受压和受拉杆件进行巧妙地组合。
sbp施莱希公司研发的一种计算工具能够结合受拉杆件和受压杆件以及弯矩，有效地分析不同设计参数下的不同的设计方案，同时结合创新的设计方式，有助于设计出独特的最优方案，这个优化的过程可以从方案阶段一直延伸到初步设计阶段甚至施工图阶段。
A lot of our ring cable roofs are developed this way. You can check out our previous “StructureTalks” articles which discuss the principles and performance of ring cable roofs.The BayArena in Leverkun, Germany is a good example for a ring cable roof with 2 compression rings at the outer edge and 1 tension ring in the center connected via radial cables.The following figure show the soccer stadium, the natatorium, and the indoo
r arena in the Suzhou Sports Center. The curvature ofthe roofs enables the system of single layer cable nets.在设计许多轮辐式屋盖结构体系时我们也运用了此种方法。前期的“StructureTalks”文章中已经探讨过轮辐式屋盖结构的设计原则和结构性能等。位于德国勒沃库森的BayArena的体育场是一座典型的采用环索屋盖结构体系的体育场，在它的外边缘上采用了2个压环，在中间采用1个拉环，压环与拉环之间通过径向索连接。
位于苏州的苏州奥林匹克体育中心包括一座体育场、一座游泳馆和一座体育馆，其马鞍形的屋盖采用了单层索网结构。
▲ Bay Arena in Leverkun: A roof structure which transfers loads to merely 8 V-columns, determined in a form-finding process. / 德国勒沃库森拜耳球场：经过找形分析，屋盖结构的荷载仅传递至8根V柱 © sbp
▲ Suzhou Sports Centre, Suzhou, China (2018) / 苏州奥林匹克体育中心 © Kris Provoost
Form-Finding for other aspects / 找形在其它方面的功用
吃药能喝绿豆汤吗Besides a pure structural optimization of the system, other aspects, e.g. a reduction of m
anufacturing effort, can require a further improvement of the geometry.Methods of modern geometry go far beyond the mere illustration and organization of space. Together with the objective of designing efficient and aesthetically appealing buildings, it also enables the optimization of structural, geometric and construction-relevant parameters.
Geometrically equal surfaces can be given great variety in appearance and expression through faceting. Reasonable gmentation can enhance the three-dimensional effect of a surface. In the field of architecture, this goes hand in hand with the logistical need for modular components. Using innovative optimization process, any surface can be divided into elegant, regular gments, while also taking account of specific requirements regarding the production and detailing of components.对几何形状进行优化除了有助于优化结构受力之外，在其它方面例如在减小加工难度方面，也有所帮助。现代科技发展水平下，找形的目的已不仅仅是为了勾勒和组织空间形状。在考虑高效性和美观性的同时，找形也会对结构、形状和施工相关的参数进行优化。
