INTERACTION OF BUTT WELDS AND HIGH-STRENGTH SCREWS OR RIVETS UNDER STATIC AND FATIGUE LOADING. PART 2 - TESTS ON GIRDERS SUBJECTED TO BENDING

ZUSAMMENWIRKEN VON STUMPFNAEHTEN MIT HV-SCHRAUBEN ODER NIETEN BEI RUHENDER UND BEI DAUERBELASTUNG. TEIL 2: VERSUCHE MIT BIEGETRAEGERN.

ACCORDING TO DIN 4100 THE COMBINATION OF DIFFERENT JOINTING MATERIALS IN ONE JOINT HAS RECENTLY BECOME ADMISSIBLE FOR STEEL STRUCTURES. BECAUSE OF THE POSSIBLE ECONOMIC ADVANTAGES IN THESE TYPES OF JOINTS THEIR FUNDAMENTAL BEHAVIOUR IN JOINTS HAVING PROFILES IPE 450 (IN WHICH ONE CHORD OF A GIRDER WAS WELDED AND THE OTHER CHORD AND THE CROSSPIECE WERE JOINED BY HV BOLTED OR RIVETTED COVER PLATES) WERE TESTED UP TO THE FAILURE POINT USING STATIC BENDING TESTS. AS THESE JOINTS ARE OF PARTICULAR INTEREST IN CRANE CONSTRUCTION SEVERAL ADDITIONAL ALTERNATING BEND TESTS WERE CARRIED OUT IN ADDITION ON A FURTHER TEST PIECE. THE STRAIN AND DEFORMATION MEASUREMENTS IN THE STATIC TESTS SHOWED NO SIGNIFICANT DIFFERENCES FROM JOINTS USING ONLY ONE JOINING METHOD; FAILURE WAS RECOGNISED BY INSTABILITY OF THE IPE PROFILE AND WAS NOT AFFECTED BY THE JOINTS; THE RESULTS OF THE FATIGUE TESTS, ON ACCOUNT OF THE NOTCH EFFECTS, ARE GREATLY DEPENDENT ON THE TECHNIQUE EMPLOYED IN MAKING THE JOINTS. THEY PERMIT A CLASSIFICATION OF THE DIFFERENT TECHNIQUES INTO DEFINITE TYPES OF NOTCH ALTHOUGH AN EFFECT DUE TO REPEATED WELDING AT THE SAME SPOT, ON ACCOUNT OF THE TYPE OF TEST TECHNIQUE EMPLOYED USING ONLY ONE GIRDER, CANNOT BE DISREGARDED. SINCE, WITH HV JOINTS THE WASHERS (SHIMS) ARE INVOLVED IN THE LOAD TRANSMISSION BECAUSE OF THE FRICTION CONTACT THESE HIGH STRENGTH COMPONENTS SHOULD NOT BE DENTED BY STAMP IMPRESSIONS.