Behaviour of End Zone of Pre-tensioned Concrete Elements

Application of high performance concrete or self-compacting concrete is verycommon in prefabrication plants. For pre-tensioned concrete structures prestressing reinforcement may be prepared in the form of smooth or profiled steel wires or multi-wire strands.The transfer of the prestressing force onto pre-tensioned element takes place through the bond between concrete and steel. Proper recognition of bond phenomenon directly influences the safety and durability of structure. It is especially important for pre-tensioned concrete elements without the normal reinforcement, such as railway sleepers or hollow core floor slabs.The value of bond stress in pre-tensioned structures depends on the value of tendon's slippage and many material and technological aspects. Complex stress state in end zone of the element, caused by transferring the prestressing force to concrete, may result in different damages. In the elements without transverse reinforcement cracking of end zone can endanger its safety use.The paper presents also the calculations of the transmission length of prestressing force according to the latest regulations - Eurocode 2 and Model Code 2010.