VTOP v.2.0

VTOP is a computer application that optimizes the pre-stress force and the longitudinal geometry of steel rods in a pre-stressed or post-stressed concrete beam. The aim of the program is to reduce the maximum pre-stress force required to support the structural loads. This is done by working out the optimum geometry of the tendons in the design.

The load assumptions of the VTOP are:

• Single load applied at the centre of the beam
• Uniformly distributed load along the beam
• Two concentrated loads applied at equal distances
• Three concentrated loads applied at equal distances

When the actual loads are none of the above mentioned, the program allows users to input envelopes of positive or negative moment values associated with the loads.

In general, the program assumes the beam to be designed with three rods; an upper rod of uniform eccentricity, an intermediate one with a variable eccentricity and a lower one with a fixed eccentricity.

Depending on the circumstances, the beam can be designed without one or two of the rods, considering only the ones you wish to include.

In the design process, the ultimate strength of the concrete under compression and tension and the design limits related to the maximum eccentricity for the rods have to be specified. Furthemore, the users can limit the radius of curvature of the rods along the beam.

From the optimum structural design point of view, VTOP solves linear optimization problems which obtain their solutions by means of the well-known SIMPLEX algorithm as described in the text called "Methods of Optimal Design of Structures", Santiago Hernández, Roads, Canals and Ports Engineer, Madrid (Spain), 1990.