SlabSTRESS in a nutshell

Nowadays, flat slabs supported on columns represent one of the most commonly used structural systems for commercial, office, industrial and residential buildings as well as for parking garages. They are very simple to construct and also to use in fact they need simple formwork and reinforcement and the flat soffit allowing an easy placement of equipment and installation underneath the slab (Muttoni 2008).

In a flat slab system, it is possible to identify three different levels of the structure from the simplest to the most complex. The first level is the isolated slab column connection; gradually there is the single floor and finally the whole building. Space limitations in the laboratory often determine the size of tests units. For this reason, many works on the behaviour of isolated slab column connection have already been done (Coronelli et al, 2015; Fanella et al., 2017; Hueste et al., 2007), fewer regarding a single storey (Hwang and Mohele, 1993; Rha et al., 2014) and not many for the whole structural system (multi storey buildings) (Fick et al., 2017; Moehle and Diebold, 1984, Kang and Wallace, 2005).

Due the growing use of flat slab structures, there is a need for a greater and deeper knowledge of the behaviour of these elements as a part of the whole system of the building together with the requirements of a European regulation.

With these aims, a new project called slab STRESS is here presented regarding tests for seismic and cyclic loading on flat slab building on a real scale.

In the program entitled “SlabSTRESS” (Slab STructural RESponse for Seismic design in Europe), flat slab floors in a real scale flat slab building will be tested for seismic and cyclic loading at the ELSA Reaction Wall of the Joint Research Centre in Ispra (Italy). The experimental campaign is part of the Transnational Access activities of the SERA (Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe) project. This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No.730900. The SlabSTRESS user team is made up of a group of European institutions, led by the Politecnico di Milano  together with EPFL Lausanne, UNOVA Lisbon and UTCB Bucharest.

The real scale of the structure testing is important because no study to date considered such thickness of the slab within a whole building structure. Moreover, the pseudo-dynamic technique will test the effective seismic response of a system with primary and secondary parts.

This system reproduces real boundary conditions of inter-story flat plate systems as well as longitudinal and transverse continuities of the floor slab, so as to precisely simulate slab moment distribution and redistribution in a span and over adjacent spans.

Finally, since the flat slab structural system is increasingly used and since there will be ever more structures, it is necessary to deal with the topic of retrofitting and repair of a slab-column connection for a given level of damage. This issue is of particular relevance for the maintenance and retrofitting of existing structures and not many works are available regarding this topic in scientific literature (Faria et al., 2012; Fernandes et al., 2017; Inácio et al., 2012; Ramos and Lúcio, 2008; Ramos et al., 2014).

Click here to see the video "SlabSTRESS enters in the ELSA laboratory"



Coronelli, D., Martinelli, L., Foti, F. (2015) “Reinforced concrete voided slabs Analysis and design of reinforced concrete voided slabs subjected to gravity and seismic actions” Dario Flaccovio Editore srl, 248 pp, ISBN 9788857904702 (English Translation available online).

Fanella D.A., Mahamid, M., Mota, M. (2017) “Flat Plate Voided Concrete Slab Systems: Design, Serviceability, Fire Resistance and Construction” ASCE Practice Periodical on Structural Design and Construction, Vol.22, 3, August.

Faria, D. M. V., Lúcio, V. J. G., Ramos A. P. (2012) “Post-Punching Behaviour of Flat Slabs Strengthened with a New Technique using Post Tensioning, Engineering Structures 40, July 2012, pp. 383-397.

Fernandes, H., Lúcio, V. J. G., Ramos A. P., (2017) “Strengthening of RC slabs with reinforced concrete overlay on the tensile face”, Engineering Structures, Volume 132, 1 February 2017, Pages 540-550, ISSN 0141-0296.

Fick, D. R., Sozen, M. A., Kreger, M. E. (2017) “Response of Full-Scale Three-Story Flat-Plate Test Structure to Cycleas of Increasing Lateral Load” ACI Structural Journal, V. 114, No. 6, pp. 1507-1518.

Hueste, M. B. D., Browining, J., Lepage, A., Wallace, J., W. (2007) “Seismic Design Criteria for Slab-column Connections”. ACI Structural Journal, V. 104, No. 4, pp. 448-458.

Hwang, S.-J., Moehle, J. P. (1993) “An Experimental Study of Flat-Plate Structures under Vertical and Lateral Loads”.Report N. UCB/EERC-93/03, Earthquake Engineering Research Center, University of California, Barkeley, Feb. 1993, 278pp.

Inácio, M. M. G., Ramos A. P., Faria, D. M. V. (2012) “Strengthening of Flat Slabs with Transverse Reinforcement by Introduction of Steel Bolts using different Anchorage Approaches”, Engineering Structures 44, November 2012, pp. 63-77.

Kang, T. H.-K., Wallace, J. W. (2005) “Dynamic Response of Flat Plate System with Shear Reinforcement”. ACI Structural Journal, V. 102, No. 5, pp. 763-773.

Moehle J. P., Diebold J. W. (1984) “Experimental Study of the Seismic Response of a Two-Story of a Flat-Plate Structure”. University of California, Berkeley.

Ramos, A. P.,Lúcio, V. J. G.(2008) “Post-punching behaviour of prestressed concrete flat slabs." Magazine of Concrete Research 60, No.4,pp. 245-251.

Ramos, A. P., Lúcio, V. J. G., Duarte,Faria, D. M. V. (2014) “The effect of the vertical component of prestress forces on the punching strength of flat slabs”, Engineering Structures, Volume 76, 1 October 2014, Pages 90-98, ISSN 0141-0296.

Rha, C., Kang, T. H.-K., Shin, M., Yoon, J. B. (2014). “Gravity and Lateral Load-Carrying Capacities of Reinforced Concrete Flat Plate Systems”.ACI Structural Journal, V. 111, No 4, 2014, pp. 753-764.