4. let's have a closer look at volcanic ash

However, the option of solid abutments on specific perimetral points is structurally not self-referential as it transfers an oblique force to the surrounding ground (diagram bottom). The thrust is not reacted only by the mass of the abutment but also by the mass of soil surrounding it.

If we reconsider this detail we might encounter failures due to the often poor and unconsolidated surface soil consistency in many parts of Quito. Therefore it was decided that tieing the abutments back to each other(diagram opposite page, bottom) and post-tensioningthe tie would be a safer option in the light of unpredictable ground conditions. Thus the load transferred to the ground is essentially vertical.

400mmsolid concreteabutment2m x 3m

thrustload

obliqueresultingvector

200mm250m

m

300mm

350mm1:100 section

profile of shell varies in thickness (moreinformation in 5.8)

ties

thrust

verticalcompression

tensiontie

GAUSSIAN

In red, areas of anticlastic curvature affected by double thrust along intersection of 2 domes.

6. emptying it out