At 23, he enrolled to study architecture at the Central University of Venezuela, where he graduated in 1956.
His best known works are the Venezuelan Pavilion in Expo Hanover 2000, Tachira Club in Caracas, Venezuela, the Holy Redeemer church in San Cristóbal, Venezuela, and the Museum of Modern Art in Caracas, Venezuela. Following graduation, he worked with other architects such as Brazilian Oscar Niemeyer and Spaniard Eduardo Torroja. Vivas" architectural style tends to consist of the International style and modernism, though he varies the two styles via naturalist and humanist influences.
His architecture style also utilizes ecology.
The best example of his work is the Venezuelan Pavilion in Hannover Expo in 2000. The pavilion is characterized by the shape of the orchid flower, which is fifty-nine feet tall and protrudes from the building with its thirty-foot petals opening and closing depending on the weather.
He joined the military political party of Venezuela, where he began to design projects for them and other communist parties.