Definition of Implosion // im-plo-sion: an instance of something collapsing violently inward.
Ok… Let’s dive deeper into this definition of implosion also known as explosive demolition. The basic idea of explosive demolition is quite simple: If you remove the support structure of a building at a certain point, the section of the building above that point will fall down on the part of the building below that point. If this upper section is heavy enough, it will collide with the lower part with sufficient force to cause significant damage. The explosives are just the trigger for the demolition as numerous small explosives, strategically placed within the structure, are used to catalyze the collapse. Gravity then comes in and brings the building down.
Depending on the structure of a building, demolition blasting team will load explosives on several different levels of the building so that the building structure falls down on itself at multiple points. Dynamite, or other explosives are used to shatter reinforced concrete supports. Linear shaped charges are used to sever steel supports. These explosives are progressively detonated on supports throughout the structure. Then, explosives on the lower floors initiate the controlled collapse. When everything is planned and executed correctly, the total damage of the explosives and falling building material is sufficient to collapse the structure entirely, so cleanup crews are left with only a pile of rubble.
In order to demolish a building safely, a qualified team such as FBUSA must map out each element of the implosion ahead of time. It’s the preplanning and the softstrip (prep work) that generally takes the most time. In the planning phase, the first step is to examine architectural and structural drawings of the building, if they can be located, to determine how the building is put together. Next, the blaster crew and professional engineers tours the building (several times), recording notes about the support structure on each floor. Once they have gathered all the raw data they need, the team hammer out a plan of attack. Drawing from past experiences with similar buildings, they decide what explosives to use, where to position them in the building and how to time their detonations. For Fabio Bruno USA, we also prefer the use of 3-D simulation software which allows us to view the implosion before it happens allowing us to check every detail and anticipate potential issues. Testing out the plan ahead of time in a virtual world is a key component to our success. This is what sets FBUSA apart from the rest of the competition as we pride ourselves in using the absolute best in proprietary digital modeling by bringing an advanced level of scientific inquiry to the examination, analysis, and study of structures. Because we are plugged into the most advanced technology in the implosion industry, we are a leader in the Explosive Demolition world and we have Applied Sciences International to thank for that. ASI has been involved with almost every single one of our implosions and the results have been spot on perfect! To see video of our 3-D simulations click here.
The main challenge in bringing a building down is controlling which way it falls. Ideally, we will be able to tumble the building over on one side, into a parking lot or other open area. This sort of blast is the easiest to execute, and it is generally the safest way to go. Tipping a building over is something like falling a tree. For example, to topple the building to the north, blasters would detonate explosives on the north side of the building first, in the same way you would chop into a tree from the north side if you wanted it to fall in that direction. Blasters may also secure steel cables to support columns in the building, so that they are pulled a certain way as they crumble.
Sometimes, though, a building is surrounded by structures that must be preserved. In this case, we would proceed with a true implosion, demolishing the building so that it collapses straight down into its own footprint (the total area at the base of the building). This feat requires such skill that only a handful of demolition companies in the world will attempt it. At FBUSA, we have imploded many high rise structures in tight quarters with neighboring buildings and have been recognized as the best in the world at true implosions. As we like to say, this is Controlled Demolition at it’s finest. Click the link to our media to see some of our implosion projects.
We approach each project a little differently, but the basic idea is to think of the building as a collection of separate structures or towers. Our blasters set the explosives so that each "tower" falls toward the center of the building, in roughly the same way that they would set the explosives to topple a single structure to the side. When the explosives are detonated in the right order, the toppling towers crash against each other, and all of the rubble collects at the center of the building. Another option is to detonate the columns at the center of the building before the other columns so that the building's sides fall inward. Additionally, we typically detonate the first 2-3 floors, then we detonate the 3rd, 4th, or 5th floor above that. Then this sequence (3rd, 4th, or 5th) repeats until we reach the top floor, however this all dependent upon the structure of the building and what our structural engineers and 3-D modeling suggest.
Every building in the world is unique and there can be a number of ways a blasting crew might bring it down. It was noted by Brent Blanchard, an implosion expert from Protec Documentation Services, the demolition of Hayes Homes, a 10-building housing project in Newark, New Jersey, which was demolished in three separate phases over the course of three years. "A different blasting firm performed each phase," Blanchard says, "and although all of the buildings were identical, each blaster chose a slightly different type of explosive and loaded varying numbers of support columns. They even brought the buildings down in different mathematical sequences, with varying amounts of time factored in between each building's collapse."
Generally speaking, blasters will explode the major support columns on the lower floors first and then a few upper stories. In a 20-story building, for example, the blasters might blow the columns on the 1st and 2nd floor, as well as the 7th and 8th floors but again it all depends on what our 3-D modeling suggests. In most cases, blowing the support structures on the lower floors is sufficient for collapsing the building, but loading columns on upper floors helps break the building material into smaller pieces as it falls. This makes for easier cleanup following the blast.
Once our team of blasters have figured out how to set up an implosion, it's time to prepare the building. In the next article, we'll find out what's involved in pre-detonation prepping or soft stripping and see how blasters rig the explosives for a precisely timed demolition. For Part 2 of the Process of Building Implosions CLICK HERE.