UNIVERSITY OF SÃO PAULO ENGINEERING SCHOOL OF SÃO CARLOS DEPARTMENT OF STRUCTURAL ENGINEERING PABLO AUGUSTO KRAHL Lateral stability of ultra-high performance fiber-reinforced concrete beams with emphasis in transitory phases Instabilidade lateral de vigas de concreto de ultra-alto desempenho reforçado com fibras com ênfase em fases transitórias São Carlos 2018