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the bridge beams were built 2013... heeheheheheThis is sooooooo 2013 Ric But a good try.....
the bridge beams were built 2013... heeheheheheThis is sooooooo 2013 Ric But a good try.....
Just bend them back? If that's the city's thinking it's no wounder they failed in the first placeThe weight of the girders will be transferred to the crane so that workers can inspect the steel beams, and begin repairing or removing them.
Just bend them back? If that's the city's thinking it's no wounder they failed in the first place
truckers!!!!
turned corner to sharp
were t-team and Maxwell working on this bridge? that would explain a bunch! lol
how so?
Girder installations are serious business and supreme is the best at it. ( girder supply and erection is typically a one contract item). from the limited details i have and a few photos my conclusion is as follows. This bridge is a single span bridge with 3 girder sections. east west and centre. This means there are no piers for the girders to cantilever and the east and west sections must be temporarily supported past the centre of gravity and chained down at the abutment ends. followed by complete cross brace installation on those completed sections before the centre girders are installed and cross braced. the girders that twisted are in the center section. Steel girders are extremely flimsy in torsion and are designed for only downward force. only when the entire girder structure is cross braced and the concrete deck is cast onto the girders does it become full strength in torsion (earthquake), side load (wind) and down force (vehcles). as girders are installed a team follows quickly behind and installs cross bracing but does not torque all bolts until complete. my "guess" is that the weight of the centre girder sections installed combined with warmer temperatures caused the temporary shoring to sink. This could even be by as little as 20mm to cause this. from the photos you can see the cross bracing team was not able to completely cross brace the damaged section before this occurred. if the shoring did in fact sink this would put extreme amounts of compression on top of the girder and tension on the bottom of the girder causing it to buckle. had they been able to fully cross brace the centre in time this likely would not have happened but it still could have due to the amount of force. In my opinion this is not a matter of poor quality steel ( this is checked and double checked before fabrication and shipping). it is also in my opinion not a fault of the installation crew but more an oversight into the temporary shoring systems in place. i would like to think i am wrong and it was something else because typically all things are considered such as temperature while the contractor and engineer are developing and approving a girder erection plan. I also have a hard time thinking this is a design flaw in the girders for 2 reasons. #1 the girders sitting with no concrete deck or traffic have less than 20% of their design load on them and i dont think they could have fawked that up that bad. #2 the computer software used to design girders is mind blowing. they run them through dynamic and static load tests, wind, earthquake etcetc tests before they are fabricated.
Just my 2c
torsional buckling, should have been braced like the ones on the left prior to disconnecting the cranes.
Sure but that's not the crane operators fault lol