Posted by Manuel Oliveros on January 01, 2003 at 09:52:05:
In Reply to: Structural engineering of the Great Pyramid of Egypt posted by Jim Lewandowski on December 31, 2002 at 10:59:46:
A good finite element program able to deal with the discrete solid blocks would be of great help. This is more likely to be found between the geotechnical engineers than even structural engineers or architects.
The question of air pressure may be non meaningful structurally. Other thing is for ritual or ventilation.
The initial explanation may have some basis, relief chambers. That they used it for ritual or constructive purposes would require more knowledge than I have to venture.
Structurally however the bigger weight at the center of the pyramid than at the edges is likely to create at the central vertical axis mostly vertical compression and corresponding horizontal tension. You can imagine this tension by thinking of the pyramid undergoing dishing action (i.e., the square plan sinks more at the center that at the corners under the weight), this attemptinmg to create a vertical hole at the center of the pyramid. Dishing action shows in most cases of our equal height buildings where the load imposed on the ground by unit surface is quite regular, and so must be an even more relevant phenomenon for pyramidal loads.
In the end, at the vertical axis and giving its size they might know from experience severe distortion (of the kind undergone) might occur under the originated spreading forces of the more or less horizontal tension. Then a trick may have been devised: where if there were not the "relieving" chambers above the king's chamber itself would have been a pre-built big crack likely to concentrate all the effects of the correspondent stress concentration, such effects wuld be minimized by 1. diverting by arch action most of the weight outside the confines of the king's chamber and relief ones (this way the major discontinuity if some would be expelled to the confines of the forced arch action, where would remain unseen, and as well spreaded to a bigger and outer area in seahring action) and 2. building the relief chambers in even more loose way and in bigger size than the king's chamber itself, this way making more likely the remaining disruption effects to concentrate in precisely the chambers above, and making it less likely to show in the king's chamber.
The roughness in the slabs making the floors or roofs of the chambers above may relate to wanting to make the likelihood of the disruption be bigger there, and also to the fact of that nonworked slabs would stand more strong against rupture that worked ones, since less likely to sustain microcracks originated upon fabrication. This would still be wanted, since what was required was a perfect king's chamber after some disruption above would have happened.
The effectiveness of the measures is anyway moderate, since as long friction permits the whole stay cohesive, effects expected of an entirely continuous structure will also show in the one made of discrete blocks. That is, the damages even if minimized are unlikely to be entirely forfeited by these measures, how less so in this massive record structure and standing for so long period of time.
Free 3D Models