What Happens During Bridge Demolition?

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An extensive bridge construction project often necessitates demolishing existing structures, an intricate task with wide-reaching effects on traffic flow and the environment. Select the best Mesa Demolition.

Conventional methods of bridge demolition typically involve static cutting, mechanical chiseling, and blasting control – these techniques usually require expressway closures lasting anywhere between six and 120 hr.

Isolating the Bridge

One critical step of bridge demolition is isolating it from moving water by damming both rivers on either side of it. This creates a dry work area for construction crews and protects wildlife and people living downstream.

Safety should always be the top priority when building bridges. Construction crews must adhere to federal and state regulations for safe operations, including providing adequate training, equipment, procedures, and emergency plans in case an incident arises.

As part of a bridge demolition, its structure must be carefully observed to ensure it is being demolished correctly. To accomplish this goal, various sensors and monitoring equipment are utilized – for instance, six dynamic strain gauges may be placed on abutments to detect stress changes during deconstruction; four inclinometers also help monitor changes in support bracket inclinations.

Recent surveys conducted among Departments of Transportation across the nation discovered that many bridge owners lack policies or procedures for overseeing demolition work. This indicates a clear need for national specifications regarding bridge demolition. While multiple methods may be used for bridge destruction projects, comprehensive documents and specifications will help reduce accidents, injuries, and worker fatalities during this process.

Explosive Demolition

Once bridges reach their end of useful life, they are typically demolished to make room for new ones. Bridges play an essential part in connecting areas, stimulating economic and community growth, and helping traffic move smoothly throughout the region.

Engineers must select an effective bridge demolition method for every particular structure they are deconstructing. While conventional methods like backhoes or cranes may suffice for certain bridges, others require explosives if demolition must take place quickly or is impractical for other means of demolition.

Explosive demolition during bridge removal typically entails strategically attaching explosive charges to load-bearing components of the structure to cause them to collapse under their own weight, also known as building implosion (although atmospheric pressure doesn’t actually pull or push a structure inward; gravity does).

This process is typically used in urban settings where collateral damage needs to be kept to a minimum. It can also be an ideal option when large volumes of debris must be cleared quickly from an area, such as when deconstructing bridges over roadways for road widening projects.

Hydraulic Breakers

Hydraulic breakers are heavy mechanical devices designed to demolish concrete, asphalt, and stone materials with their percussive force, shattering them into smaller pieces.

Construction cranes are ideal for difficult material that’s hard to break apart manually or with a hammer, as well as projects like bridge removal, where contractors have limited timeframes to complete the task.

Hydraulic breakers are powered by hydraulic systems that deliver high-pressure fluid to a piston. The piston strikes a chisel against the piston to produce an impact that shatters the material’s surface and widens cracks as it moves back and forth. Depending on your project, there are various styles and sizes of hydraulic breakers; side-type breakers work best when breaking apart concrete walls, while top-type ones perform best when breaking larger rocks or boulders.

The material type also impacts performance. According to Bigwood, hydraulic accumulators may be added to breakers to increase their blow energy when hitting harder material. These units store hydraulic oil that the piston recoils from each strike and use it again on subsequent strikes to increase the striking power of the hammer.

City Circle Demolition used hydraulic breakers from Indeco to meet its tight deadline for demolishing an overpass on Duncan Road in southern California in just 22 hours – minimizing traffic disruption and allowing the route to open as scheduled.

Dismantling

The superstructure of a bridge (deck, trusses, cables, and towers above water) should usually be disassembled carefully before being recycled for reuse. Meanwhile, its piers below water may need to be demolished using explosives.

Destruction requires careful planning and is usually very time-consuming. Safety is of primary concern to nearby structures and the public. Therefore, conducting an in-depth structural analysis, installing appropriate barricades and warning signs, using controlled demolition techniques, and minimizing dust and noise during the project is of the utmost importance to its success.

At the same time, it is also crucial to consider how demolition will impact traffic if a bridge crosses highways or rivers. To mitigate its effect, demolition must occur so as to allow rapid reconstruction with new structures or at least the reopening of local transportation networks as soon as possible.

This study presents a non-blasting and efficient rapid demolition method based on SPMT for bridge demolition to minimize traffic disruptions and environmental pollution during its demolition process. To achieve this objective, key technology involves designing a unique cutting system capable of cutting into multiple parts of the old bridge body before transport. Furthermore, stability, synchronization, and influencing parameters of this cut bridge body-transport system were analyzed extensively as well as an application of this method to demolish a crossline symmetrical rigid frame arch bridge in China within 5 hours demonstrated its feasibility and efficiency.