If the connecting piece over the joint between the two halves had been inside the arch the collapse would been less likely.
The joint is the weak point and under load the arch would bend at the joint. If the connecting piece was inside the arch it woule have come under tension and provided it di not snap would have kept the side of the joint pressed into each other. Being on top it went into compression and could have acted as a fulcrum to force the joint apart.
The joint is the weak point and under load the arch would bend at the joint. If the connecting piece was inside the arch it woule have come under tension and provided it di not snap would have kept the side of the joint pressed into each other. Being on top it went into compression and could have acted as a fulcrum to force the joint apart.