Design of earthquake-resistant structures according to Eurocod 8 is not based on the concept of acceptable/tolerable probability of exceedance of the near collapse limit state. Rather than that standard introduces fundamental non-collapse and damage limitation re-quirements, which are associated with the design seismic action. It is foreseen that the non-collapse requirement issatisfied when the regular structure does not collapse in the case of an earthquake with a return period of 475 years. Probability of such an even in 50 years is 10%. Therefore it is obvious that probability of failure of structures, which would be designed strictly according to the fundamental non-collapse requirement, would be unacceptable for society. Due to factors ofsafety involved in design the structures withstand much stronger earthquakesin comparison to an earthquake with a period of 475 years. In orderto assess which factor of safety have the greatest impact on the overall safety of code-conforming buildings, two multi-storey reinforced concrete buildings were investigated. The strength and the system ductility of the six variants of the structures were evaluated on the basis of the pushover analysis gradually taking into account the requirements of the Eurocode 2 and 8, as well as gradually excluding the design assumptions. Safety in design of the buildings was evaluated by the difference between the calculated and prescribed behaviour factor, by the ratio between the design ground acceleration and that associated with the near collapse limit state, which wasassessed using the N2 method, and by the escalation of safety in terms of probability of exceedance of the near collapse limit state. The results of this analysis are dis-cussed in the paper. For the investigated buildings it is shown that the design seismic action has the greatest impact on the yield strength of the structure and the peak ground accelera-tion, which cause the near-collapse limit state. On the other hand, the partial factors of mate-rialstrength contribute around 50% to the return period of the near-collapse limit state, whereas the contribution of the capacity design principles to overall safety is minor.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 6303073The paper presents an experimental study of seismic resistance of reinforced concrete columns for the purpose of analysing the influence of uncertainty of material characteristics and uncertainty in manufacture. In order to cover all of the considered sources of uncertainty, 12 columns were manufactured in three different companies. The same plan and nominally the same materials were used in the production of the columns. In addition to the material characteristics, the influence of lapping of longitudinal reinforcement on the seismic response of columns was analysed as well. The columns were tested with cyclic horizontal load, which was increased until collapse. The research has shown that there are big differences in the manufacture of the columns, which is observed in the seismic response after reaching the maximum capacity. The biggest influence on the ductility can be attributed to the detailing of the stirrups. The research has also confirmed some already well-known dependences and demonstrated that one of important parameters of the seismic resistance of columns might be the location of the first stirrup above the foundation.
F.01 Acquisition of new practical knowledge, information and skills
COBISS.SI-ID: 7886177The invited lecture entitled Risk-informed engineering: From force-based design to loss assessment of buildings was given at University College London, on the invitation of Tiziana Rossetto, professor of earthquake engineering from University College London, who has managed to gain the ERC project on earthquake engineering. The emphasis was on the dissemination of the results obtained within the project sponsored by Slovenian Research Agency. We agreed that both research institution will try to prepare proposals for European projects and strengthen collaboration through the exchange of young researcher.
B.04 Guest lecture
COBISS.SI-ID: 7096417The concept of intensity-based assessment for risk-based decision-making was recently introduced, and realized by 3R method (Record selection, Response analysis and Risk-based decision making), which can be used to check the adequacy of structural seismic safety. The objective of the method is estimation whether the seismic collapse risk is lower or larger in comparison to target collapse risk, which is assumed acceptable. This can be estimated with high accuracy on basis of results of only few nonlinear dynamic analyses at single intensity by using carefully selected ground motions, which are termed characteristic ground motions (CGMs). The engineer can decide that the structural seismic collapse safety is suitable when collapse is observed in the case of less than half of, for example, seven CGMs. On the other hand, if collapse is observed in case of more than half CGMs, the collapse risk is estimated to be too large. The decision model is therefore straightforward, if appropriate CGMs are used. The purpose of this application is to select seven CGMs in a user friendly manner. The selection of CGMs in the 3R method is two-step procedure. In the first step the ground motions are selected in accordance with the target collapse risk and seismic hazard at the site. In the second step the smaller set of seven CGMs is selected on basis of computationally non-demanding analysis of simplified structural model with one degree of freedom, which is defined on basis of pushover analysis results. CGMapp performs this selection automatically, which enables fast and efficient decision-making about adequacy of seismic safety in accordance with the 3R method.
F.15 Development of a new information system/databases
COBISS.SI-ID: 7333985Company JUBHome has developed low-energy house system with structural walls JUBHome WALL. The walls consist of modules which have two layers of thermal insulation, which are interconnected with plastic ties. In the space between insulation layers, horizontal and vertical reinforcement is installed which is then filled with concrete. Because such type of construction is not taken into account by the provisions of current seismic regulations, it was necessary to develop technical guides for designers. The development of designer’s guide consisted of experimental tests as well as numerical studies aiming to satisfy the basic requirements of damage limitation and collapse prevention. The basis for numerical simulations were experimental tests, which were carried out for individual elements. Based on the experimental results, we evaluated the mathematical models for deformation capacity and strength of structural elements and the impact of uncertainty in the construction of the building. We have also calibrated overstrength factor, which is necessary for assessing the real capacity of the elements. In the numerical simulations we studied the behaviour of a large number of structures built according to this system considering the minimum requirements from the standard. We conducted a parametric study on these structures, evaluated their response at various ground motion intensities and assessed their seismic risk. Based on this, we determined the minimum area of the walls in the structure to ensure proper behaviour and reliability of such facilities.
F.11 Development of a new service
COBISS.SI-ID: 7996769