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Purdueenginerd

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Posts posted by Purdueenginerd

  1. I cycle a good bit in the city. I'll ride on westheimer occasionally (normally only inside the loop). My safety protocol is the consume the entire lane. I don't want cars trying to edge by me and clip me. If an automobile wants to pass me, they need to change lanes. In addition, riding in the far right doesnt give me sufficient maneuvering room in the event of debris or accidents infront. I do this for my safety.

     

    The other thing I do when riding city streets is use significant amount of hand signals to let cars know where I'm going. I use hand signals to let them know I'm braking, and hand signals to let them know I'm changing lanes. I follow all traffic laws. 

     

    That being said, I've never been a huge fan of critical mass. While I'm all for sharing the roads, I'd be a lot more supportive of critical mass if they stopped at traffic lights, did not weave between moving cars, and cut off 2 ton vehicles. That's not a way to spread  your message--- its a way to piss people off and put yourself in danger. I'm stereotyping, because not all CM riders are jerks and ride recklessly. I think its a lot more constructive of a message if CM stayed within the traffic laws. "Share the rode" Implies cars and bikes... not overwhelming cars.

  2. Interesting! If in fact it was a wind induced failure --- What's interesting to me is that the lateral system failed before the actual tarp or whatever they used to secure the tarp to the scaffold (tie wire, for example). Engineered scaffolding must account for wind loading. 

     

    Note, on the side of the building on the first picture, there are 3 holes in rectilinear formation. I think (hard to tell) that is the lateral anchor supports that tie the scaffold to the primary structure. There's no discernible structural damage in those locations, It would appear the anchor failed. The failure at that point could have been brought on by improper installation, improper anchors, impact load from a falling scaffold (failure brought on by something else), and windloads beyond design specifications.... there are multitude of reasons that anchor could have failed. 

    Just some food for thought/discussion from the codes:
     

    "(12) Work on or from scaffolds is prohibited during storms or high winds unless a competent person has determined that it is safe for employees to be on the scaffold and those employees are protected by a personal fall arrest system or wind screens. Wind screens shall not be used unless the scaffold is secured against the anticipated wind forces imposed."

     

     

    Now if the contractors added wind screens without engineering approval, this would have altered the loading characteristics of the scaffold. 
     

    The footing or anchorage for scaffolds shall be sound, rigid, and capable of carrying the maximum intended load without settling or displacement. Unstable objects such as barrels, boxes, loose brick, or concrete blocks shall not be used to support scaffolds or planks.

     

     

    Scaffolding contractors like to cut corners on this. I can't see the footings in any of the pictures.

     

     

     

    Scaffolds and their components shall be capable of supporting without failure at least four times the maximum intended load.
    To prevent movement, the scaffold shall be secured to the building or structure at intervals not to exceed 30 feet horizontally and 26 feet vertically.

     

     

     

    Thank goodness no one was hurt...

     

    Ninja edit from the OSHA guidelines. for 3' or wider bases

     

    3150_4.jpg

     

     

     

    Ninja edit 2:

     

     

    Supported scaffolds with a height to base width (including outrigger supports, if used) ratio of more than four to one (4:1) shall be restrained from tipping by guying, tying, bracing, or equivalent means, as follows:

    1926.451©(1)(i)

    Guys, ties, and braces shall be installed at locations where horizontal members support both inner and outer legs.

    1926.451©(1)(ii)

    Guys, ties, and braces shall be installed according to the scaffold manufacturer's recommendations or at the closest horizontal member to the 4:1 height and be repeated vertically at locations of horizontal members every 20 feet (6.1 m) or less thereafter for scaffolds 3 feet (0.91 m) wide or less, and every 26 feet (7.9 m) or less thereafter for scaffolds greater than 3 feet (0.91 m) wide. The top guy, tie or brace of completed scaffolds shall be placed no further than the 4:1 height from the top. Such guys, ties and braces shall be installed at each end of the scaffold and at horizontal intervals not to exceed 30 feet (9.1 m) (measured from one end [not both] towards the other).

    1926.451©(1)(iii)

    Ties, guys, braces, or outriggers shall be used to prevent the tipping of supported scaffolds in all circumstances where an eccentric load, such as a cantilevered work platform, is applied or is transmitted to the scaffold.

     

    /disclaimer: No engineering calculations or analysis has been done on this structure by me, do not interpret this post as an engineered statement on the cause of collapse. 

     

  3. I am going to bet that it is going to be a little too noisy for the owners to sit outside and enjoy a bottle or three of tequila during the week (rush hour, pollution, traffic, violence, etc) considering it is right next to the highway.

     

    Violence? Hardly. I think statistically that area is in line with midtown and downtown.

    Rush hour- I drive through that area for my commute all the time- It's hardly inconvenient. Traffic on the street level isnt bad at all during rush hour. On 45... that area is a bit irritating. But residents will hop on I-45 well south and north of that location. I would guess a significant percentage of the residents would work in downtown/medical district as well... making traffic on 45--irrelevant. 

    Particulate Pollution: PM2.5 and PM10 do tend to be higher in areas directly adjacent to interstate highways... and in the city in general. 

    Sound Pollution: Sound resistant windows and doors do a lot to remedy that.

     

    Also, Who drinks 3 bottles of tequila in one sitting? 

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