Ingegneria civile: Il ponte ad arco più grande del mondo, The Third Pingnan Bridge in Guangxi (Cina) скачать в хорошем качестве

Ingegneria civile: Il ponte ad arco più grande del mondo, The Third Pingnan Bridge in Guangxi (Cina)

http://gabrielemartufi.altervista.org © The Third Pingnan Bridge / CGTN / ECNS /    / chinesebridge   / 2020 Il terzo ponte di Pingnan, situato nella regione autonoma del Guangxi Zhuang, nel sud della Cina, è attualmente il ponte ad arco più grande del mondo, con una campata di 575 metri. È un ponte ad arco tubolare in acciaio riempito di cemento (CFST, Concrete-Filled Steel Tube). Il terzo ponte di Pingnan è un capolavoro di ingegneria civile e, nello specifico, di ingegneria strutturale. World's Longest Arch Bridge, The Largest Arch Bridge in the World, The Largest-Span Arch Bridge in the World. 28 December 2020 The Third Pingnan Bridge in Guangxi (China), with a main span of 575 meters, this 1,035-meter-long bridge has consumed 15,000 tons of iron. Engineers designed an abutment built on a pebble layer, with about five millimeters of submergence observed until now. It has surpassed the span of Chaotianmen Bridge, resetting the world record. "The cost of an arch bridge is 100 million yuan less than a suspension bridge or 40 million yuan less than a cable-stayed bridge of the same length. Yet, it is more durable and costs less in maintenance," said Zheng Jilian, a professor of Guangxi University, and an academician of the Chinese Academy of Engineering. A through arch bridge, also known as a half-through arch bridge or a through-type arch bridge, is a bridge that is made from materials such as steel or reinforced concrete, in which the base of an arch structure is below the deck but the top rises above it. It can either be lower bearing or mid-bearing. Thus, the deck is within the arch, and cables or beams that are in tension suspend the central part of the deck from the arch. For a specific construction method, especially for masonry arches, the proportions of the arch remain similar no matter what the size: wider arches are thus required to be taller arches. For a semi-circular arch, the height is half of the span. Bridges across deep, narrow gorges can have their arch placed entirely beneath a flat roadway, but bridges in flatter country rise above their road approaches. A wide bridge may require an arch so tall as to become a significant obstacle and incline for the roadway. Arch bridges generate large side thrusts on their footings and so may require a solid bedrock foundation. It is often impossible to achieve a flat enough arch, simply owing to the limitations of the foundations – particularly in flat country. Historically, such bridges often became viaducts of multiple small arches. With the availability of iron or concrete as structural materials, it became possible to construct a through arch bridge: a bridge where the deck does not have to be carried over the top of the arch. This requires a structure that can both support the deck from the arch by tension rods, chains or cables and allow a gap in the arch, so the deck can pass through it. The first of these in particular cannot be achieved with masonry construction and requires wrought iron or steel. The use of a through arch does not change the proportions or size of the arch: a large span will still require a tall arch, although this can now reach any height above the deck without obstructing traffic. The arch may also reach downwards at its sides, to either reach strong foundations or to place the roadway at a convenient height for spanning a deep valley from a plateau above. 28 December 2020 The world's largest span arch bridge Guangxi Pingnan Third Bridge, The Third Pingnan Bridge completed and opened to traffic. Innovations in Design, Construction, and Management of Pingnan Third Bridge, World's Longest Arch Bridge, The Largest-Span Arch Bridge in the World, The Largest Arch Bridge in the World. The main bridge of Pingnan Third Bridge is a half-through concrete-filled steel tubular (CFST) arch bridge with a span of 575 m, and it is the largest-span arch bridge worldwide. Several innovative technologies were proposed and adopted with respect to the design, construction and management of Pingnan Third Bridge (3rd Pingnan Bridge, Pingnan 3rd Bridge), including: integrated design and prefabricated construction technologies based on the independent cantilever unit concept to accelerate the assembly of the steel truss for the main arch; a BeiDou Navigation Satellite System (BDS) based active force control and displacement adjustment technology for the construction tower and a force optimization model for the one-time tensioning of buckled cables; the vacuum-assisted filling technique integrated with an advanced timed expansion and shrinkage compensation technology that generally solved the historically stubborn defect of in-tube concrete de-bonding and voiding in the CFST arch bridge industry; a novel composite bridge foundation of the diaphragm wall encapsulating a grouting-reinforced pebble layer for the northern abutment of the Pingnan Third Bridge. https://en.wikipedia.org/wiki/Through...