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Virginia Tech：滨河城市瑞德福市位于弗吉尼亚州，2018年该市委托弗吉尼亚理工大学为当地设计一座新的观景台，以便让公众可以登高欣赏附近静谧流淌的新河(New River)以及远处颇具历史意义的铁路桥。瑞德福市的一项主要发展目标，就是提倡使用清洁技术和低碳建筑产品，以此展示该市从其过去工业结构中的转型。在接下来的两年项目期内，弗吉尼亚理工大学组建的一支跨学科师生团队共同合作研究，最终设计并建造了这座23米长、9米高的公共建筑。在设计前期阶段，团队成员将关注点聚焦于新兴建筑技术——交叉层压木材(CLT)，这种材料因其强度、可持续性和独特的空间特性而受到关注。随着设计的不断推进，项目团队发现将工业生产的交叉层压木材运送到项目现场的碳成本非常高，为降低碳成本，团队不得不将思路转向“当地利用”，这便要求大家对从当地采购的原材料进行创造性地应用。
Virginia Tech：In 2018, the riverfront city of Radford, Virginia approached Virginia Tech – a nearby public research university – to assist the town with the visioning for a new train observation tower that would provide public access to views over the adjacent New River and a historically significant railroad bridge. A primary project objective for the city was the use of clean-tech, low-carbon building products as a way to showcase the city’s transition away from its industrial past. Over the following two-year project period, an interdisciplinary faculty and student team partnered to research, design, and build the 75-foot long by 30-foot high public building. Early in the design process, the students chose to focus on emerging building technology – cross-laminated timber (CLT) – due to its strength, sustainability, and unique spatial properties. As the design process progressed, the project team discovered that the carbon cost to ship industrially produced cross-laminated timber panels to the project site was too high and, as such, the project team was forced to “think local” in order to cut carbon costs, thus entailing the creative application of locally-sourced raw materials.
低碳产品的开发 Low-carbon product development
Following the culmination of years of research across multiple university departments, the resulting custom-developed, hardwood cross-laminated timber (HCLT) product utilizes low-grade Yellow Poplar lumber regionally sourced from oversupplied, hardwood-dominant forests. The custom HCLT product not only outperformed all other commercially available CLT in the U.S. market – notably made from softwoods – but the product’s raw materials were also sourced and up-cycled within a two-hundred-mile radius of the project site.
With research beginning at the scale of a lab sample, and resulting in the 5-foot by 10-foot high-strength panels, the student and faculty team was able to incorporate unique architectural features into the project that aligned with the HCLT’s robust performance metrics, namely 3-inch thick structural cantilevers, and exterior exposed structural members. In the United States, the production of CLT is governed by APA/PRG-320 code requirements, which only permit construction with certified softwood panels. As such, the project team pursued a performance-based approval process for the custom product through the collection of data relating to its structural and moisture-related performance, and its susceptibility to UV, fungal, and insect degradation, a key part of the interdisciplinary project process.
模块化建造 Modular construction
Perched above the New River on a steeply sloping brownfield site, the challenging site conditions required the project team to prefabricate building components in a controlled environment offsite. The project’s architectural design involves two modular HCLT cubes that are bisected by a public walkway. The walkway begins at grade and culminates in a 20-foot-high cantilever as the site drops steeply towards the river.
▽公共走道将观景台一分为二 The modular HCLT cubes that are bisected by a public walkway
▽步道从地面开始延伸并在6米高的悬臂处结束，架空步道下方是陡然向河流倾斜的场地 The walkway begins at grade and culminates in a 20-foot-high cantilever as the site drops steeply towards the river
Due to complicated site logistics, including the ruins of a Civil-war era building discovered under the project’s foundations during construction, the project team entirely prefabricated one 10-foot by 15-foot HCLT module that was then subsequently craned into place on-site, with a six-inch tolerance from surrounding trees. The New River Train Observation Tower is the first project globally to utilize modular HCLT construction methods in a permanent building, thus entailing unique and careful detailing to keep the cantilevering, panelized system water protected and safe from racking during construction. The project is also globally unique as an example of exterior-exposed structural elements made from laminated hardwood. Each screw hole was impregnated with liquid wax, and then the entire exterior envelope was coated in a linseed oil and natural pine tar mix to protect it from UV, heat, and moisture damage.
▽建造过程 The process
▽外壳保护观景台免受紫外线、高温和湿气的损害 The entire exterior envelope was coated to protect it from UV, heat, and moisture damage
The project is the first permanent, HCLT building permitted in the United States. And, through a research and development process that piloted the custom up-cycling of low-value locally sourced materials, it sets a benchmark for low-carbon, research-based, sustainable construction.
项目建筑师：Edward Becker, Kay Edge
设计团队：Kirt Hilker, Robert Riggs, and Virginia Tech students
合作者：Dr. Daniel Hindman, Dr. Tom Hammett, Dr. Henry Quesada, Dr. Joseph Loferski, Dr. Brian Bond
供应商：Henard Metal Fabricators, Walder Foundation Products, Helix Steel, Chandler Concrete
Official Project Name: New River Train Observation Tower
Location: Radford, Virginia
Project completion date: 2021
Client: City of Radford, Virginia
Budget: 101,000 USD
Project Architects: Edward Becker, Kay Edge
Design team: Kirt Hilker, Robert Riggs, and Virginia Tech students
Primary Material: Hardwood cross-laminated timber
Collaborators: Dr. Daniel Hindman, Dr. Tom Hammett, Dr. Henry Quesada, Dr. Joseph Loferski, Dr. Brian Bond
Engineers: Truesdell Engineering
Suppliers: Henard Metal Fabricators, Walder Foundation Products, Helix Steel, Chandler Concrete
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