The following event happened while I was at work today. It is a first hand experience, being that I was one of the locals working on the equipment at the time of the incident. All the names of those involved as well as the companies, location, and artist will be withheld for the protection of the rights of all. With that said, here I go.
This morning it all started at a normal load in. The venue was a temporary arena and grandstand set up by my employer for the summer. The roof, I believe, is the largest that the manufacture offers. The artists arrived, providing all their own production (lights, audio, and video). All was going well, the lights were all in the air, and audio was on its way up. We took our break and when we came back I was reassigned to video. We knew we were in for a lot of work because there were five, two ton motors rigged for the video LED wall alone. We get the first row (each row is four LED panels high) floating in the air. There is a little bounce, but that is understandable because the roof has a certain amount of give. We get the second row hung and flown, still now major problems, it still had a lot of bounce in the wall. We get the third row hung, and flown but it had a tremendous amount of bounce, and took a lot to get it flown. We get to the fourth row (only two LED panels high) that was split over five carts, half on one side half on the other. We get it all lined up and locked together and start to bring the wall in to connect the fourth row to the third. The video guy brought in the wall and it bounced in real hard, but close enough for us to start to connect the rows. Something was not level so the video guy attempted to level the wall so we could connect the half row. He did not like how it came in so he called over some crewmates to assess the situation. With the half row still unattached he proceeded to lift the wall. He held the up button for 2-3 seconds and the wall did not move. At that point the decision was made to ground stack the last half row. The video guy then proceeded to lift the wall over the nubs on the last row, so we could slide the half row out. And then it happened. The wall jerked, there was a loud crack, and we all left the deck. What had happened was that one of the three main roof trusses buckled shifting the weight of the video wall to the half row underneath, pushing a caster through the deck. Luckily, NO ONE WAS HURT. From there we went to lunch and waited for a crane to come and support the roof while we slowly loaded out everything.
Although there is not an official cause, there has been a lot of finger pointing.
There was talk that the deck gave out first causing a shock of weight on the roof. I was right there. I don’t think so.
There were bad welds on the roof truss. This is possible.
The way in which the points were rigged put undue stress on the roof. This is the most likely cause. An employee of the roof company was on hand (every time the roof in moved or rigged upon) and said the points were ok, knowing that there were to be 2-ton motors. The two points that potentially caused the problem were the outside points which were bridled between two cross members of the roof. It is thought that the extra weight of the bumps pulled the cross members together causing the roof truss to buckle and break most of the welds in that section of truss.
The buckle in the roof caused the back half of the roof to tweak, even the corner blocks.
The roof engineers said the roof could take that much weight. The total weight of the wall was around 7 tons.
We lowered in the roof and looked at the damage, and the section was mangled pretty badly.
Here are some pictures.
http://www.svsu.edu/~jmsinick/roof1.jpg
http://www.svsu.edu/~jmsinick/roof2.jpg
http://www.svsu.edu/~jmsinick/roof3.jpg
The show was rescheduled for a later date.
Jeremy
This morning it all started at a normal load in. The venue was a temporary arena and grandstand set up by my employer for the summer. The roof, I believe, is the largest that the manufacture offers. The artists arrived, providing all their own production (lights, audio, and video). All was going well, the lights were all in the air, and audio was on its way up. We took our break and when we came back I was reassigned to video. We knew we were in for a lot of work because there were five, two ton motors rigged for the video LED wall alone. We get the first row (each row is four LED panels high) floating in the air. There is a little bounce, but that is understandable because the roof has a certain amount of give. We get the second row hung and flown, still now major problems, it still had a lot of bounce in the wall. We get the third row hung, and flown but it had a tremendous amount of bounce, and took a lot to get it flown. We get to the fourth row (only two LED panels high) that was split over five carts, half on one side half on the other. We get it all lined up and locked together and start to bring the wall in to connect the fourth row to the third. The video guy brought in the wall and it bounced in real hard, but close enough for us to start to connect the rows. Something was not level so the video guy attempted to level the wall so we could connect the half row. He did not like how it came in so he called over some crewmates to assess the situation. With the half row still unattached he proceeded to lift the wall. He held the up button for 2-3 seconds and the wall did not move. At that point the decision was made to ground stack the last half row. The video guy then proceeded to lift the wall over the nubs on the last row, so we could slide the half row out. And then it happened. The wall jerked, there was a loud crack, and we all left the deck. What had happened was that one of the three main roof trusses buckled shifting the weight of the video wall to the half row underneath, pushing a caster through the deck. Luckily, NO ONE WAS HURT. From there we went to lunch and waited for a crane to come and support the roof while we slowly loaded out everything.
Although there is not an official cause, there has been a lot of finger pointing.
There was talk that the deck gave out first causing a shock of weight on the roof. I was right there. I don’t think so.
There were bad welds on the roof truss. This is possible.
The way in which the points were rigged put undue stress on the roof. This is the most likely cause. An employee of the roof company was on hand (every time the roof in moved or rigged upon) and said the points were ok, knowing that there were to be 2-ton motors. The two points that potentially caused the problem were the outside points which were bridled between two cross members of the roof. It is thought that the extra weight of the bumps pulled the cross members together causing the roof truss to buckle and break most of the welds in that section of truss.
The buckle in the roof caused the back half of the roof to tweak, even the corner blocks.
The roof engineers said the roof could take that much weight. The total weight of the wall was around 7 tons.
We lowered in the roof and looked at the damage, and the section was mangled pretty badly.
Here are some pictures.
http://www.svsu.edu/~jmsinick/roof1.jpg
http://www.svsu.edu/~jmsinick/roof2.jpg
http://www.svsu.edu/~jmsinick/roof3.jpg
The show was rescheduled for a later date.
Jeremy
