Institut für Baustoffe, Massivbau und Brandschutz, TU Braunschweig
Baustoffe und Massivbau, Fachbereich Bauingenieurwesen, HS Ostwestfalen-Lippe


In the research project “prestressed masonry walls under seismic load“ of the Institute for building materials, concrete structures and fire protection (IBMB) at the TU Braunschweig and the FH Lippe and Höxter (FH LuH) an improved shear bearing capacity of masonry walls under seismic loads due to higher axial force was shown. Room-high, prestressed masonry walls were loaded by static cyclic head displacement just like seismic loads. The masonry walls were prestressed by tendons with light prestressing jacks. Compared to non-reinforced masonry a considerably higher horizontal resistance was detected. There were used the nonlinear FE – Analysis to calculate the load bearing and deformation behaviour. In the contribution these results are shown, as well as the implementation of the research results on buildings exposed to earthquakes. Furthermore it is presented that prestressed masonry walls can be used to stabilize buildings with few bracing walls (e.g. townhouses) if the structural analysis with unreinforced masonry wall fails. At the new hall building of the MPA Braunschweig the bracing of the building was realized directly by means of vertically prestressed walls. Prestressing forces can be determined following DIN 1045-1. Decompression calculations have the task to guarantee masonry walls without cracks for all action combinations in the serviceability limit state. Axial forces as the result of prestressing do not cause second order effects, if the tendons remain in their place of the cross section during buckling of the wall. To calculate the load bearing capacity of prestressed masonry walls the safety concept of DIN 1055-100:2001-03 can be used in combination with the design-specific definitions of DIN 1053-100:2006-07 for masonry.

Key words
prestressed, masonry, monochord, earthquake, shear reinforcement