PSI - Issue 64

Urs Meier et al. / Procedia Structural Integrity 64 (2024) 29–39 Meier/Winistörfer / Structural Integrity Procedia 00 (2019) 000 – 000

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from the building were conducted. The first test, performed on an unaltered floor beam, confirmed the anticipated brittle behavior associated with the scarcity of shear stirrups. The second test, employing a with post-tensioned CFRP loops post-strengthened floor beam, validated the chosen methodology with post-tensioned CFRP tendons. The observed ductile failure attributed to a pure bending mechanism underscored the efficacy of the strengthening solution. Based on the comprehensive tests conducted, it was determined that the allowable service load for the unenhanced floor beams stood at 200 kg/m 2 . The concurrent implementation of shear strengthening measures, coupled with the identified structural reserves of the flexural reinforcement, provided empirical justification for elevating the permissible service load to the current standard of 300 kg/m 2 .

Fig. 4a. Cross section of the T-beam supporting the Hourdi slab. Dimensions in [mm].

Fig. 4b. Apertures next to the beam were broken out without damaging the steel reinforcement.

Fig. 4c. Steel saddles, supported by mortar, were fitted to all corners of the beam. Dimensions in [mm].

Fig. 4d. Loop tendon termination.

The renovation of buildings from the pioneering days of concrete construction places the highest demands on engineers, technicians and craftsmen alike. The stages of the Leuenhof project described above are shown in detail in Figures 4a to 4h. Figure 5 shows a section of one of the refurbished slabs. A total of 1300 Carbo-Link Loop systems with the brand name "CL Restrap" were installed in the Leuenhof. The application of CFRP loops described above is unique in its significance in a long series of applications of CFRP loops in the renovation of historic buildings. According to Kempe (1999), it began in 1994 with the renovation of the roof truss of the Gothic Frauenkirche in Meissen. Follow ups were described by Huster et al. (2008) and Lees and Winistörfer (2011).