Forschung

The following research projects have been carried out by the group of Prof. Bachmann:

Earthquake Scenarios for Switzerland - Vulnerability of Existing Structures
The goal of the research project Earthquake Scenarios for Switzerland is to improve the assessment of seismic hazard, to investigate the vulnerability of the built environment and to elaborate risk scenarios. The study has focused on certain target areas in the region of Basel.

Nonlinear dynamic analysis of reinforced concrete buildings
The equivalent force method commonly used in practice is only intended for regular buildings. For building structures with irregular distribution of stiffness and mass more advanced methods such as nonlinear time history analysis are required. Corresponding tools were developed.

Nonlinear seismic response of arch and gravity dams including reservoir and foundation
The purpose of the project is to develop mathematical models for a realistic prediction of the seismic response of arch and gravity dams. Important aspects are the nonlinear behaviour of dams and the interaction of dams with their reservoir and their foundation. A key aspect of the project is the development of algorithms for the interaction problems in the time domain. These algorithms allow including nonlinear dam behaviour and interaction problems simultaneously in an analysis.

Structures under pseudodynamic action
With the pseudodynamic test method it is possible to simulate the dynamic behaviour of a structure with a static test. The equation of motion of a computer model of the test specimen is integrated incrementally during the experiment. For each step of the integration, inertial and damping forces are calculated analytically while the nonlinear restoring forces are measured.

Reinforced concrete structures under cyclic static action
In the framework of this project the behaviour of reinforced concrete structures under seismic action were studied experimentally. The test results together with numerical simulations were used to develop practical rules for design and construction.

Reinforced concrete structures under cyclic dynamic action
Even though computer methods for the nonlinear analysis of reinforced concrete structures are getting more and more refined, shake table tests are important for the verification and calibration of numerical models. The tests served to determine important input parameters of the numerical models. The tests also demonstrated that ductile reinforced concrete structures really have the energy dissipation capacity usually assumed in seismic design.

Vibration problems in structures
Theoretical and experimental investigations have been carried out in connection with vibration problems in structures caused by rythmic man-induced vibrations, machine-induced vibrations as well as high winds.

Torsion and ductility demands on buildings under seismic action
Torsional behavior of asymmetric buildings under earthquake action was studied numerically in connection with local ductility demands. The aim of the study was to define rules that will ensure a better consideration of nonlinear torsional effects.

Reinforcing steel under cyclic static action
The main goal of this project was to determine essential constitutive relations for the nonlinear dynamic analysis of reinforced concrete structures. Additionally, standards were defined, guaranteeing sufficient ductility of reinforcing steel.

Seismic upgrading of existing structures
Approximately 95 % of the existing structures in Switzerland were not designed for seismic action or based on obsolete rules. These structures are in general very vulnerable and possess an unknown, often inadequate, seismic safety. Even in the case of a moderate earthquake, human casualties and severe damage have to be expected, especially damage to the environment caused by chemical plants. Efficient methods and measures were developed to improve the seismic performance of existing vulnerable structures.