Could we build a wooden skyscraper? - Stefan Al

Prevodilac: Katarina Šimšić Lektor: Milenka Okuka

Towering 85 meters above the Norwegian countryside,

Uzdižući se 85 metara nad norveškim pejzažom,

Mjøstårnet cuts a sleek shape in the rural skyline.

Mjostarnet predstavlja elegantan prizor na seoskom horizontu.

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

Sa 18 spratova ispunjenih restoranima, apartmanima i hotelskim sobama,

this modern building might seem out of place.

ova moderna zgrada bi se mogla učiniti neumesnom.

But a deeper look reveals it actually blends in quite well

Ali na drugi pogled ćete otkriti da se zapravo jako dobra stapa

among the forested farmlands.

sa šumovitim zemljištima.

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

To je verovatno zato što je Mjostarnet najviša drvena zgrada na svetu,

made almost entirely from the trees of neighboring forests.

koja je skoro u potpunosti napravljena od drveća susednih šuma.

Until the end of the 20th century,

Do kraja 20. veka,

engineers thought it was impossible to build

inženjeri su smatrali da je nemoguće izgraditi

a wooden building over six stories tall.

drvenu zgradu sa više od šest spratova.

Traditional boards of lumber were fairly strong against forces

Tradicionalne drvene daske su bile poprilično otporne na sile

parallel to the wood’s fiber growth.

koje su paralelne drvenim vlaknima.

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

Međutim, bile su osetljive na vertikalno primenjene sile.

As a result, wood lacked steel’s tensile strength

Kao rezultat, drvetu je nedostajala zatezna čvrstoća čelika

or concrete’s compressive strength—

ili jačina pritiska betona;

each necessary to support tall buildings

obe neophodne za podupiranje visokih zgrada

and battle the powerful winds found at high altitudes.

i odbranu od snažnih vetrova na velikim nadmorskim visinama.

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

Ali ranih 1890-ih je izumljena laminacija drveta lepkom tj. glulam.

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

Jedan vek kasnije, inžinjeri su razvili unakrsno lamelirano drvo ili CLT

These new wooden materials start out like all other lumber;

Ovi novi drveni materijali su započeli kao i svaka druga građa;

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

sveže posečeni balvani se tešu u glatke i jednake drvene daske.

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

Zatim, u slučaju CLT-a, ploče se lepe u naizmeničnom smeru

with each layer set at 90 degrees to its neighbors.

sa svakim slojem postavljenim na 90 stepeni naspram susednog.

The resulting material benefits from wood’s structural rigidity

Dobijeni materijal koristi strukturnu krutost drveta

in every direction,

u svim pravcima

allowing it to mimic the compressive strength of concrete

što mu omogućava da imitira betonsku jačinu pritiska

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

i podnese opterećenja do 20 puta veća od tradicionalne građe.

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

Glulam, sa druge strane, lepi daske u istom pravcu,

forming massive beams with tensile strength comparable to steel.

formirajući masivne grede zatezne čvrstoće uporedive sa čelikom.

Glulam isn’t as versatile as CLT,

Glulam nije toliko svestran kao CLT,

but its incredible strength along one direction makes it superior

ali njegova neverovatna snaga duž jednog pravca ga čini superiornijim

for load-bearing beams and columns.

za nosive grede i stubove.

These engineered forms of wood could finally compete with traditional materials

Ovi konstruisani oblici drveta su se konačno mogli takmičiti sa tradicionalnim,

while also bringing their own unique set of advantages.

istovremeno donoseći i svoj jedinstveni skup prednosti.

At one-fifth the weight of concrete,

Kako je za petinu lakši od betona,

building with CLT requires smaller cranes, smaller foundations,

izgradnja sa CLT-om zahteva manje dizalice, manje temelje,

and fewer construction workers.

i manje građevinskih radnika.

While concrete has to undergo a time-intensive process

Dok beton mora proći kroz dugotrajan proces

of casting and curing in a mold,

livenja i očvršćavanja u kalupu,

timber can be shaped quickly using computer directed cutting machines.

drvo se može lako oblikovati sa programiranim mašinama za sečenje.

And where concrete requires certain weather and timing conditions

I dok beton zahteva određene vremenske uslove i pogodan trenutak

to be poured on site,

za izlivanje na lokaciji,

engineered wood can be prefabricated in a factory,

konstruisano drvo se može unapred proizvesti u fabrici,

creating standardized parts with clear instructions for assembly.

stvarajući standardizovane delove sa jasnim instrukcijama za montažu.

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

Zajedno, ovi materijali omogućuju bržu i tišu izgradnju,

with more biodegradable materials and less waste.

sa više biorazgradivih materijala i manje otpada.

Once constructed, CLT and glulam buildings are also more resilient

Nakon izgradnje, CLT i glulam zgrade su takođe otpornije

to some natural disasters.

na neke prirodne katastrofe.

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

Zemljotres može da slomi beton i trajno oslabi celu strukturu.

But cracked wood panels can be easily replaced.

Ali ispucale drvene ploče se lako mogu zameniti.

The same is true for fire safety.

Isto važi i za protivpožarnu sigurnost.

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

Kako temperature rastu u CLT zgradi, spoljni sloj materijala će se ugljenisati,

insulating the inner layers for up to three hours.

izolujući unutrašnje slojeve i do tri sata.

This is more than enough time to evacuate most buildings,

Ovo je više nego dovoljno vremena za evakuaciju većine zgrada,

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

a kad se dim slegne, ugljenisane ploče se mogu zameniti—

unlike melted steel beams.

za razliku od topljenih čeličnih greda.

But perhaps the biggest benefits of CLT and glulam

Ali možda su najveće prednosti CLT-a i glulama izvan gradilišta.

are outside the construction site.

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

Konstrukcija zgrada je odgovorna za 11% godišnjih globalnih emisija ugljenika,

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

a proizvodnja čelika, betona, gvožđa i stakla

are major contributors to that figure.

najviše doprinosi toj brojki.

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

Drvo je, međutim, obnovljivi resurs koji se može učiniti karbonski neutralnim,

if trees are planted to replace those cut down.

ako se drveće zasadi na mesto posečenog.

Wood also has low thermal conductivity,

Drvo ima i nisku toplotnu provodljivost

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

što olakšava zagrevanje i hlađenje zgrada uz manje energetskog otpada.

Despite these advantages, CLT requires vastly more lumber

Uprkos ovim prednostima, CLT zahteva znatno više građe

than traditional wooden construction.

od tradicionalne drvene konstrukcije.

And when compared in similar quantities,

I kada se uporede u sličnim količinama,

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

ni CLT, ni glulam nisu toliko jaki kao čelik ili beton.

Even Mjøstårnet isn’t made entirely of wood,

Čak ni Mjostarnet nije u potpunosti napravljen od drveta,

as it contains concrete slabs to reinforce the upper floors.

već sadrži betonske ploče za učvršćivanje gornjih spratova.

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

S obzirom na ovo, mala je verovatnoća da bi čisto drvena konstrukcija

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

bila dovoljno čvrsta da podupre zgradu od 40 spratova—

the minimum height for a formal skyscraper.

što je minimalna visina zvaničnog nebodera.

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

Ali čak i ako su samo zgrade ispod 30 spratova izgrađene od drveta,

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

to bi smanjilo emisiju ugljenika tih struktura za više od 25%.

So no matter how tall these wooden buildings rise,

Dakle, bez obzira na to koliko su visoke ove drvene zgrade,

each one contributes to the health of our concrete jungles.

svaka doprinosi zdravlju naših betonskih džungli.