# Box Girder Distortion: Stability Geometry Explained

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In summary, a box girder under pressure is not simple. The bone in a skull is a beam of 2 layers of cortex about 2mm thick with trabeculae connectors about 4mm. Surgical chisels are 2mm thick or less to avoid side deflected shock, cracking and so jamming the chisel in surgery. A razor blade striking bone cause erratic cracking from the tip.
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I have minimal engineering knowledge. Air speed resistance is linear with surface area as is static pressure from a standing body. A box girder under pressure is not simple. The bone in a skull is a beam of 2 layers of cortex about 2mm thick with trabeculae connectors about 4mm. Surgical chisels are 2mm thick or less to avoid side deflected shock, cracking and so jamming the chisel in surgery. A razor blade striking bone cause erratic cracking from the tip.

An analogy may be a naval destroyer with sharp bow hitting a wood wharf with timber piles and cross-timbers. A broad merchant ship may have twice the width in the bow but the effect of high speed wharf collision may not be just half the penetration. The box girder wharf may spread the force out wider causing a shallow complex distortion. The collected broken timbers may further broaden the front force .

Could the final effect be a damaged area that is 3, 4, 5 times the width of the merchant ship? A skull has been excavated with excised bone and an Australian Aboriginal wooden sword-blade is assumed to be the cause. These are about 5mm thick at 10mm back from edge but the smooth excision fracture looks like a metal sword cut ( say 3mm thick). Any comments on the stability geometry of box girders will be appreciated .

Your posting is too much of a jumble to really understand what you are asking about . Can you explain the basic problem more clearly and ask some specific questions ?

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The final q. is : would a sword of 5mm blade thickness be likely to slice a skull bone 8mmm thick, like a 2mm thick blade cuts ? Given the 2mm limit for a slicing action before erratic side damage , what proportions of force would act in this box-girder geometry? Bone researchers don't know the answer so I'm just hoping for general comments . The 4mm length of trabeculae connectors may be relevant if the force strikes their whole length rather than mid-point. I'm guessing the whole thing would collapse in a depression fracture.

## 1. What is a box girder distortion?

A box girder distortion is a type of structural deformation that occurs in box girder bridges, which are bridges that are composed of two parallel girders connected by a deck. This distortion can result in changes in the bridge's stability and geometry, which can affect its overall strength and ability to support heavy loads.

## 2. What causes box girder distortion?

Box girder distortion can be caused by a variety of factors, including uneven distribution of weight on the bridge, temperature changes, and external forces such as wind or earthquakes. In some cases, it can also be attributed to design flaws or material defects.

## 3. How does box girder distortion affect the stability of a bridge?

Box girder distortion can significantly impact the stability of a bridge by altering its geometry and reducing its load-carrying capacity. It can also lead to uneven distribution of weight and stress on the bridge, which can increase the risk of structural failure.

## 4. What measures can be taken to prevent box girder distortion?

To prevent box girder distortion, engineers can incorporate various design features such as stiffening systems, expansion joints, and reinforcement in critical areas of the bridge. Regular inspections and maintenance can also help to identify and address any potential issues before they become more severe.

## 5. Can box girder distortion be repaired?

In some cases, box girder distortion can be repaired through techniques such as post-tensioning, which involves applying tension to specific points of the bridge to correct any deformations. However, the extent of the distortion and the underlying cause must be carefully evaluated before determining the appropriate repair method.