THEORY OF THE SHORT-TERM STRENGTH AND PERMANENT STRENGTH OF CONCRETE SUBJECTED TO MULTIAXIAL LOADING

STUDIE ZUR THEORIE DER KURZZEITFESTIGKEIT UND DER DAUERSTANDFESTIGKEIT DES BETONS MIT MEHRACHSIGER BEANSPRUCHUNG

A THEORY FOR DESCRIBING THE STRENGTH AND DEFORMATION OF CONCRETE UNDER HIGH UNIAXIAL CONSTANT LOADING WAS DEVELOPED WITHIN THE FRAMEWORK OF THE RESEARCH PROJECT V 152 "PHYSICAL TESTING OF CEMENT STONE - CREEP (RESISTANCE) LIMIT OF CEMENT STONE AND CONCRETE". THE SIGNIFICANT RESULTS OF THE THEORY WERE CONFIRMED BY TESTS ON CEMENT STONE, MORTAR AND CONCRETE. IN ORDER TO BE ABLE TO CONSIDER THE MULTIAXIAL STRAIN STATE FREQUENTLY ENCOUNTERED IN PRACTICE THE THEORY OF DEFORMATION AND STRENGTH OF CONCRETE, ALREADY DEVELOPED AND WELL CONFIRMED BY EXPERIMENT, MUST BE EXTENDED IN ORDER TO BE ABLE TO DESCRIBE, IN ADDITION, THE BEHAVIOUR IN THE MULTI-AXIAL STRESS STATE. THE WORK IS TO BE REGARDED AS A THEORETICAL SUPPLEMENT TO THE COMPREHENSIVE RESEARCH PROGRAMME HAVING AS ITS THEME "MULTI-AXIAL STRENGTH OF CONCRETE" UNDERTAKEN BY THE INSTITUT FUR MASSIVBAU (INSTITUTE FOR MASSIVE CONSTRUCTION). THE EXTENSION OF THE THEORY WILL NECESSITATE A CONSIDERABLE AMOUNT OF COMPUTER TIME ON THE TR 440. USING THIS THEORY WILL ENABLE THE WELL-KNOWN STRENGTH DIAGRAM TO BE FORMULATED ANALYTICALLY FROM EXPERIMENTAL STUDIES. THE FORMATION OF MICRO-CRACKS AND THE ONSET OF THE MACROSCOPIC FRACTURE STATE CAN BE CALCULATED, WITH THE AID OF A MATHEMATICAL ANALYSIS, FROM THE PROBABILITY OF THE OCCURRENCE OF STRAIN PEAKS.