Could we build a wooden skyscraper? - Stefan Al

譯者: Ming Hsuan Lu 審譯者: Yi-Ping Cho (Marssi)

Towering 85 meters above the Norwegian countryside,

米約薩塔高85公尺，位於挪威鄉村， 簡約的外型在天際線上顯得突出。

Mjøstårnet cuts a sleek shape in the rural skyline.

Housing 18 stories of restaurants, apartments, and hotel rooms,

這棟18層建築中有 餐廳、公寓和飯店房間，

this modern building might seem out of place.

如此現代的建築可能會顯得格格不入，

But a deeper look reveals it actually blends in quite well

但細看會發現米約薩塔 其實相當融入周遭的森林農地。

among the forested farmlands.

This is likely because Mjøstårnet is the world’s tallest wooden building,

這可能是因為米約薩塔 是全世界最高的木造建築，

made almost entirely from the trees of neighboring forests.

建材幾乎完全來自鄰近森林的樹木。

Until the end of the 20th century,

直到20世紀末，

engineers thought it was impossible to build

工程師都認為不可能

以木材建出超過六層的建築。

a wooden building over six stories tall.

Traditional boards of lumber were fairly strong against forces

傳統的木頭板材能夠抵擋

和纖維方向平行的外力，

parallel to the wood’s fiber growth.

But they were vulnerable to forces applied perpendicular to this direction.

但碰到與纖維垂直的外力就容易斷裂。

As a result, wood lacked steel’s tensile strength

因此，木材的抗拉強度不如鋼，

or concrete’s compressive strength—

抗壓強度又不如混凝土，

each necessary to support tall buildings

而建材要有這兩種強度才能撐起高樓，

and battle the powerful winds found at high altitudes.

在高空的強風中屹立不搖。

But the early 1890s saw the invention of glue laminated timber, or glulam.

但集成材於1890年代初期問世，

And a century later, engineers developed cross-laminated timber, or CLT

一個世紀後， 工程師又研發出直交集成板。

These new wooden materials start out like all other lumber;

這些新型木材在製程初期 和一般木材類似，

a freshly cut log is sawed into smooth uniform boards of wood.

剛砍下的木頭會被鋸成 相同大小的平滑木板，

Then, in the case of CLT, the boards are glued together in alternating orientations

接著，若要製成直交集成板， 就將木板以方向交錯的方式黏合，

with each layer set at 90 degrees to its neighbors.

每一層的方向都和上下層互相垂直。

The resulting material benefits from wood’s structural rigidity

這樣的製造方法利用木頭結構 在各個方向上的剛性，

in every direction,

allowing it to mimic the compressive strength of concrete

使木材能有和混凝土類似的抗壓強度，

and bear loads up to 20 times heavier than traditional lumber.

並承受比傳統木材多20倍的重量。

Glulam on the other hand, glues boards together in the same direction,

而集成材則是將木板 以方向相同的方式黏合，

forming massive beams with tensile strength comparable to steel.

製造出抗拉強度堪比鋼材的木樑。

Glulam isn’t as versatile as CLT,

集成材的運用範圍不如直交集成板廣，

but its incredible strength along one direction makes it superior

但在單一方向上的強度優異，

因此更適合用於需要承重的梁柱上。

for load-bearing beams and columns.

These engineered forms of wood could finally compete with traditional materials

木材經過這些設計， 終於能和其他傳統建材競爭，

while also bringing their own unique set of advantages.

而且還有自己獨有的優勢。

At one-fifth the weight of concrete,

直交集成板的重量 是混凝土的五分之一，

building with CLT requires smaller cranes, smaller foundations,

以其建造可用較小的起重機， 地基也可以造得比較小，

and fewer construction workers.

需要的工人也比較少。

While concrete has to undergo a time-intensive process

混凝土需要大量時間

of casting and curing in a mold,

入模並凝固成型；

timber can be shaped quickly using computer directed cutting machines.

木材則能以電腦控制的機器快速裁切。

And where concrete requires certain weather and timing conditions

且混凝土需要特定的天氣和時間條件，

to be poured on site,

才能在工地上施作；

engineered wood can be prefabricated in a factory,

工程木材則可以預先在工廠製作，

creating standardized parts with clear instructions for assembly.

做出標準化、有明確組裝指示的零件。

Taken together, these materials allow for faster and quieter construction,

綜合以上，使用這些木材 能讓工程更快速安靜，

with more biodegradable materials and less waste.

材料比較能生物降解， 產生的廢棄物也較少。

Once constructed, CLT and glulam buildings are also more resilient

直交集成板及集成材建築建成後 也較能抵擋某些自然災害。

to some natural disasters.

An earthquake can crack concrete, permanently weakening an entire structure.

混凝土若因地震破裂， 整個結構都會受到永久損害，

But cracked wood panels can be easily replaced.

但木板即使破裂，也能輕易替換。

The same is true for fire safety.

火災的情形下也是一樣，

As temperatures rise in a CLT building, the material’s outer layer will char,

直交集成板建築中溫度上升時， 木材的外層會先炭化，

insulating the inner layers for up to three hours.

能替內層的材質隔絕熱長達三小時。

This is more than enough time to evacuate most buildings,

對大部分建築來說， 這段時間很足以用來疏散，

and once the smoke has settled, charred panels can be swapped out—

而且在煙霧散去後， 炭化的木板也能被換掉，

unlike melted steel beams.

不像熔化的鋼材難以替換。

But perhaps the biggest benefits of CLT and glulam

不過直交集成板和集成材最大的優勢

are outside the construction site.

可能不在於施工現場。

Building construction is responsible for 11% of annual global carbon emissions,

建築工程在每年全球 碳排放量中佔11%，

and the production of steel, concrete, iron, and glass

其中鋼、混凝土、鐵和玻璃的生產

are major contributors to that figure.

都是提高碳排量的主要因素。

Timber, however, is a renewable resource that can be made carbon-neutral

然而木材屬於可再生資源，

只要種植樹木來代替砍下的樹， 就能達到碳中和。

if trees are planted to replace those cut down.

Wood also has low thermal conductivity,

木材的熱導率也較低，

making it easier to heat and cool buildings with less energy waste.

因此使建築升溫或降溫較容易， 浪費的能源也較少。

Despite these advantages, CLT requires vastly more lumber

不過雖然有這些優勢， 製造直交集成板所需的木頭

than traditional wooden construction.

卻比傳統木造結構多很多。

And when compared in similar quantities,

而且在數量相近的前提下，

neither CLT or glulam is as strong as steel or concrete.

直交集成板和集成材的強度 都不如鋼或混凝土。

Even Mjøstårnet isn’t made entirely of wood,

就連米約薩塔也並非完全以木材建成，

as it contains concrete slabs to reinforce the upper floors.

而是以混凝土板來強化高樓層的結構。

Taken together, it’s unlikely that a purely wooden structure

總結以上，完全木造的結構不太可能

would be strong enough to support a 40-story building—

撐起40層以上的建築，

the minimum height for a formal skyscraper.

達到摩天大樓的標準。

But even if only buildings under 30 stories were built from wood,

但就算只有那些30層以下的建築 是以木材建成，

it would reduce the carbon footprint of those structures by more than 25%.

也能為這些建築 減少超過25%的碳足跡。

So no matter how tall these wooden buildings rise,

因此這些木造建築不論有多高，

each one contributes to the health of our concrete jungles.

都能對這片水泥叢林的健康做出貢獻。