Lifetime-Oriented Structural Design Concepts- P18: At the beginning of 1996, the Cooperative Research Center SFB 398 financially supported by the German Science Foundation (DFG) was started at Ruhr-University Bochum (RUB). A scientists group representing the fields of structural engineering, structural mechanics, soil mechanics, material science, and numerical mathematics introduced a research program on “lifetimeoriented design concepts on the basis of damage and deterioration aspects”. | 228 3 Deterioration of Materials and Structures material properties reinforcement S500 structural steel S460 concrete C35 45 studs S235 J2G3 C450 sliding layer PTFE greased S235 Fig. . Details of test beam VT1 in the interfaces between steel and concrete and data of the strain states of the steel beams and the concrete slabs were collected continuously during all test phases. Without additional measurements or detailed monitoring it is not possible to determine the failure of studs. As known from the push-out tests the damage process in the interface between steel and concrete proceeds continuously and steel beam - headed studs - sliding layer side a 4 24 side b 54 headed studs 022 - h d 125mm 22mm la-27a lb-27b 250 3 HEA 300 675 6600 i o o o o o i 1 11 17 1 1 o 1 o o o o o 1 1 27_ @ 262x140x10 stiffener I 200 250 22 x 250 ------ ------------- sliding plate 675x300 on PTFE-foil each 1mm thick - PTFE double sided greased - cut-out 0 40 mm 100 Experiments 229 230 3 Deterioration of Materials and Structures transducers VT1 strain gauges oriented in longitudinal direction QS1 - QS7 mm 50 QS2 QS6 20 7 50 QS2 QS6 20 bl 1500 transducers side A 1125 675 1125 1125 1125 675 QS0 QS1 QS2 QS3 QS4 QS5 QS6 QS7 QS8 strain gauges oriented in longitudinal direction QS1 - QS7 transducers 50 50 side A 50 QS2 QS6 1500 horizontal transducers side A 50 QS2 QS6 20 400 400 Tf 400 400 400 1125 1125 1125 1125 QS0 QS1 QS2 QS3 QS4 QS5 QS6 QS7 QS8 400 400 vertical transducers side A Fig. . Test setup of test beams VT1 and VT2 side A n VT2 so no significant change in properties of a beam can be observed after single stud failure. In order to avoid a complete shear failure of studs the studs of one row of each beam were coupled in an electric circuit. According to the circuit shown in Figure shear failure during a cyclic loading phase can be detected when the corresponding LED starts to flicker or .
