ABSTRACT
ABSTRACT: The stability and tightness of the concrete outer tank has to be guaranteed by an appropriate design also under cryogenic conditions. The relevant codes provide a lot of formal regulations, but give no precise indications for analytical procedures and criteria which have to be applied in the design. Hence, the following paper deals with the behaviour of reinforced and prestressed concrete sections in direct contact with LNG, considering thermal strains and consecutive crack formation. Mechanical models, which have to be clear and simple, are discussed. The course of sectional forces and displacements due to a temperature gradient of 180◦C after failure of the inner tank are outlined for areas below and above the LNG level. Substantial design criteria are proposed and discussed. Essential in this respect are the thickness of the residual compressive zone, the reinforcement steel stresses and the characteristic crack width. By means of ingenious models, a way for the direct understanding of the coherence between the strains and deformations imposed by the temperature gradient and the above design criteria is pointed out.
