The diagram of prestressed concrete pipes of circumferential prestressing may be with or without ______

In the case of large tanks, the base slabs is subdivided by ______

The prestressed concrete poles for power transmission lines are generally designed as members with ______

The spherical domes are supported by a ring beam at the ______

The main advantage of prestressed concrete piles over traditional reinforced and concrete steel piles is ______

In circular prestressing, the member may be prestressed by overlapping ______

The investigations by Marshall have shown that prestressing considerably reduces ______

An ingenious method of casting spherical shells at the centre with conical shape was adopted by ______