IRIS – 2012 Benchmark, Parts I and II

IRIS 2012 Benchmark

Part I: Overview and summary of the results
Part II: Lessons learned and recommendations

Part I: Overview and summary of the results

An abstract of the technical paper presented at:
SMiRT-22
San Francisco, California, USA
August 18–23, 2013

Prepared by:
Nebojsa Orbovic¹, François Tarallo², Jean-Mathieu Rambach³ and Andrei Blahoianu⁴

¹Technical Specialist, CNSC-CCSN, Ottawa, ON, Canada 2 Civil Engineering Expert
²IRSN, France
³Dr-Engineer, Civil Engineering Expert, IRSN, France
⁴Director, CNSC-CCSN, Ottawa, ON, Canada

Abstract

A benchmark of numerical simulations of projectile impacts on reinforced concrete (RC) slabs has been launched in the frame of OECD/NEA/CSNI research program under the acronym IRIS. The goal of the research program is to simulate RC structural, flexural and punching behavior under soft and hard missile impact. The first phase the IRIS_2010 was a blind prediction of the tests performed ant VTT facility in Espoo, Finland. The results showed significant scatter of the results for both flexural and punching simulation. The IRIS_2012 is the second, post-test phase of the benchmark with the goal to improve simulations and reduce the scatter of the results. Based on the IRIS_2010 recommendations and to better calibrate concrete constitutive models, a series of tri-axial tests as well as Brazilian tests were performed as a part of the IRIS_2012 benchmark. 25 teams from 11 countries took part in this exercise. The majority of participants were part of the IRIS_2010 benchmark. Participants showed significant improvement in reducing epistemic uncertainties in impact simulations. Several teams presented both finite element (FE) and simplified analysis as per recommendations of the IRIS_2010. The improvements were at the level of simulation results but also at the level of understanding of impact phenomena and its modeling. However, due to the complexity of the physical phenomena and its simulation (high geometric and material non-linear behavior) and inherent epistemic and aleatory uncertainties, the scatter remains important especially comparing to conventional, linear structural engineering analysis.

To obtain a copy of the abstract's document, contact the CNSC. When contacting the CNSC, please provide the title and date of the abstract.

Part II: Lessons learned and recommendations

An abstract of the technical paper presented at:
SMiRT-22
San Francisco, California, USA
August 18–23, 2013

Prepared by:
Nebojsa Orbovic¹, François Tarallo², Jean-Mathieu Rambach³ and Andrei Blahoianu⁴

¹Technical Specialist, CNSC-CCSN, Ottawa, ON, Canada 2 Civil Engineering Expert
²IRSN, France
³Dr-Engineer, Civil Engineering Expert, IRSN, France
⁴Director, CNSC-CCSN, Ottawa, ON, Canada

Abstract

A benchmark of numerical simulations of projectile impacts on reinforced concrete slabs has been carried out in the frame of OECD/NEA under the acronym IRIS_2012. That exercise enlightened the conditions under which some 25 teams using various calculation codes could analyze the dynamic behavior of concrete slabs impacted by either deformable or rigid missiles.

Due to the fast dynamic nature of the solicitation and to the non-linear nature of the concrete, there is an inherent scatter of the results well beyond the scatter of an elastic analysis. Thus, for better understanding and modeling of the physical phenomena involved, a combination of testing and simulation is mandatory. Despite the scatter of the results, the benchmark has pointed out a number of sound methods and numerous skilled teams among the participants, leading to recommendations of good practice. Simplified analyses, with engineering attitude, have to be systematically adopted in parallel to the necessarily sophisticated simulations because those analyses allow quick sensitivity studies and better understanding and simulating of the basic phenomena by the engineers. The results of a numerical simulation should be accompanied by an appropriate margin taking into account the accuracy range of the analysis. A future objective is to continue to enhance existing models, so that their coefficient of variation would be less than 20 percent. The next phase of benchmarking will be focused on induced vibrations. The privileged way is the definition and performing of a precision test and its simulation through benchmarking that allows the multiplicity of models and the benefits of their inter-comparison.

To obtain a copy of the abstract's document, please contact us at cnsc.info.ccsn@cnsc-ccsn.gc.ca or call 613-995-5894 or 1-800-668-5284 (in Canada).  When contacting us, please provide the title and date of the abstract.