The rapid expansion of China’s high-speed rail network in recent years has spurred the usage of automated launching gantries for bridge construction.
The rapid expansion of China's high-speed rail network in recent years has spurred the usage of automated launching gantries for bridge construction.
Since the deployment of the first 900-ton capacity gantry for the construction of a full-span bridge on the Beijing-Tianjin high speed railway nearly a decade, China's construction industry has developed a broad range of launching machines and technologies for the development of full-span prefab bridges under a variety of circumstances.
An outstanding example of these bridge building giants is the SLJ900/32, developed by construction equipment company Beijing Wowjoint Machinery Co. The mobile bridge erecting machine is a construction industry behemoth, weighing 580 tonnes and measuring 91.8 metres in length, nine metres in height and 7.4 metres in width.
Like all launching gantries for bridge construction, the machine dispenses with the need for conventional crane techniques when it comes to the creation of horizontal span structures. It instead employs segmental launching methods for the sequential construction of load-bearing bridges.
The machine commences construction at the edge of the bridge and extends itself over empty air toward free-standing towers which it initially employs as props to support itself in place. Once the machine is firmly positioned, the next segment of the bridge is dropped into place from its belly and connected to the tower, providing it with more solid support for further extension.
The widespread use of these machines by China's bridge builders for almost a decade has led to the development of a wide range of innovative launching gantry technology, including launching carriers equipped with underbridges that are capable of proceeding through tunnels, launching gantries that can handle double box beams and launching gantries with longer under bridges.
While launching gantries are generally bespoke pieces of equipment developed with specific bridge designs or conditions in mind, Chinese engineers are trying to extend the usefulness and capabilities of the machines by reconfiguring them for subsequent usage under a variety of circumstances.
Their hope is to cut down on the immense capital costs of developing launching machines that are customised for usage with only a very limited number of projects before becoming obsolete.