Much of the thrust concerned how the horizontal component of the concrete load was dealt with.
Unless I am sorely mistaken, concrete subject to gravity exerts only a vertical force. If the pin-ended struts had been themselves vertical, then there would have been no need for the complexities described. – First year statics!
Of course, the reaction from the sloping construction joints would have a horizontal component, but even this could have been eliminated by making them horizontal.
DAVID TEAL (M), Aeolus Partnership, Ashford Kent, firstname.lastname@example.org