Kotvení předpjaté frp výztuže pro betonové konstrukce

Abstract

Předpětí FRP výztuže v betonových konstrukcích eliminuje její negativní vlastnost, kterou je nízký modul pružnosti. Článek popisuje vyvinutý způsob kotvení, který požívá FRP materiály i pro kotevní oblast. Základní princip návrhu je popsán v textu. Výsledky analytického návrhu jsou porovnány s experimenty, které byly provedeny v rámci řešení výzkumného projektu AdMaS.Non-metallic reinforcement has many advantages, but there are some areas of application that need to be resolved to improve the usage of FRP reinforcement in real conditions. One of the disadvantages of FRP reinforcement is its lower modulus of elasticity, which leads to greater deflections of structures and can also cause early propagation of cracks. The paper deals with the possibility of eliminating this problem by prestressing the reinforcement. It covers several problems related to anchoring and current anchoring methods used world-wide. The paper also mentions some drawbacks of these methods. In an effort to bypass these drawbacks a new anchoring method has been developed. It differs in the way longitudinal forces are transferred from the bar to the surrounding concrete. Basically, it is based on the addition of an additional anchoring member (cylinder) on the surface. This member is made of polymers so the whole system remains completely steel-free and very simple to produce. Before using the system in real structures a series of tests were performed and the results are presented. Also, some prestressed test panels were prepared and compared with standard panels.