Sep 18
Sep 18
Complete Bridge Demolition
Shoring Towers to OWSJ
“Blow’d up real good.” – John Candy
Part 1 – Part 2 – Part 3 – Citations
Common Bridge Demolition Processes for Entire Removal
When a bridge is to be replaced, the original bridge must be removed so that the new one may be constructed. Various methods exist for the removal of large structures, inclusive of heavy impact breaking, hydraulic shearing, staged removal, and explosives.
Heavy impact breaking [2] is a common method for demolishing large portions of a structure. This type of demolition is commonly used by either large scale pneumatic drills (Figures 7 and 12), or a ball-and-crane set up (Figure 13), where a large mass is swung or dropped onto the structure to break it up into pieces (helicopter mounted balls and rig mounted “whiphammers” also exist, which involve a restrained arm attached to a spring, that releases blows onto a structure at high speeds). Ball-and-crane demolition in specific is very dangerous because if the crane misses the ball may swing wide enough to tilt the crane over (Figure 14). Heavy impact breaking is popular because it is simple and can do massive damage, however it is not effective for structures surrounded by people or attached to other structures because it can create large clouds of dust, loud noise, and large vibrations. In addition, for structures with stressed tendons, heavy impact breaking is dangerous because uncontrolled dislodging of the tendons can be hazardous when they lose their anchorage and snap. Furthermore, impact breaking may have difficulty cutting reinforcement, thus requiring cutting in sequence with the breaking.
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Sep 17
Selective Bridge Demolition
Part 1 – Part 2 – Part 3 – Citations
“Do not remove a fly from your friend’s head with a hatchet.” – Ancient Chinese Proverb
Diamond Cutting Saw
Common Selective Bridge Demolition Processes
Selective demolition involves removal of part of the structure which is to be replaced. This process may take the form of cutting or mini-blasting. Cutting bridge sections is a measure of demolition in which parts of the bridge are cut out for replacement and many methods for doing so exist. Mini-blasting involves dislodging parts of the structure with small explosives. Depending on demolition requirements, wire cutting, diamond sawing, splitting, jack-hammering, abrasive water jetting, or mini-blasting may be used.
Sep 16
Never play cards with the Joker
A Beginner’s Guide to Bridge Demolition
Part 1 – Part 2 – Part 3 – Citations
Introduction
“I’m a simple man. I like dynamite, and gunpowder, and gasoline!” – The Joker.
With the growing number of engineering services available today, it’s easy to do some realistic comparisons. This article provides some great tips and helpful hints as it applies to why using an engineer is the safest way to demolish bridges. Whether its complete bridge demolition or selective demolitions complete control and predictable outcomes is synonymous with safety. This article will be published in 3 parts for you to enjoy. It will include some pretty wild videos that illustrate demolition done properly and demolition gone bad. Here is the introduction.