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Publications in Scientific Journals:

S. Lu, R. Heuer:
"Seismic assessment of lifeline masonry structures using an advanced material model";
Structural Control & Health Monitoring, 14 (2007), 321 - 332.



English abstract:
A new approach for seismic assessment of lifeline structures consisting of unreinforced masonry (URM) walls is presented. In the context of the associate material model an appropriate combination of yielding surfaces in the stress space, i.e., fracture criteria, characterizes all failure modes of the masonry. Since, due to international safety limits, permanent (plastic) deformations have to be avoided in lifeline structures, a computational strategy is developed for investigating the elastic capacity of the building. Compared to the material model of Ganz [1], the new model is extended to cover also tension strength aspects of masonry, which exist in that (non-plastic) range of material properties. The new material law is implemented into the Finite Element (FE) software ANSYS considering all fracture criteria, and an automatic procedure for determining the geometrical parameters of the masonry structures in the global FE-model is integrated. Additionally to the theoretical background, applications and numerical examples are presented. In a first step, laboratory experiments are used to test and calibrate the material model, and second, illustrative examples of an earthquake excited three story structure is analyzed numerically utilizing the advanced material model. In one example the structure consists of soft uniaxially spanned timber beam slabs, while in another application the URM building exhibits rigid RC flat slabs. Comparisons are also given between the results of the new material model, considering tension strength, and of the model according to Ganz, indicating a noticeable increase of carrying capacity within the non-plastic range.

Keywords:
unreinforced masonry (URM), material model, seismic assessment, plasticity theory, finite element method, ANSYS

Created from the Publication Database of the Vienna University of Technology.