The structural behavior of concrete

Concrete is often considered to be the ultimate construction material, thanks to its considerable strength, relatively low cost and the virtually limitless design capabilities. The research group of prof. dr. ir. Luc Taerwe and prof. dr. ir. Stijn Matthys studies the structural behavior of concrete, currently focusing on the following topics:
Recent examples of the structural failure of concrete structures have demonstrated the limitations of current design methods. While current methods focus on the design of individual beams, columns and slabs, the favourable interaction between these elements is very often neglected. Consequently, studying the robustness of concrete structures is a research domain of significant importance and would allow for a performance based design at acceptable costs to society. One of the major aspects related to the robustness of concrete structures is the membrane action of reinforced concrete slabs. Experimental and numerical research on membrane actions at large deformations is currently performed with a unique full-size test set-up (Dirk Gouverneur). 

Fig.1. Full-size test set-up on membrane action in reinforced concrete slabs.Structuralbehavior.jpg
Full-size test set-up on membrane action in reinforced concrete slabs.


A second research domain is related to the structural behavior of concrete during and after fire exposure, especially with respect to the correct assessment of the residual strength of concrete elements. Currently, research is being performed in order to quantitatively evaluate the effect of different design alternatives on the safety level of concrete structures exposed to fire, including the study of related risk based decision making and risk transfer mechanisms (Ruben Van Coile). Another study is focusing on the influence of thermal restraint on the fire resistance of concrete elements. Calculation procedures to include transient strain and practical design methods for beams subjected to different types of thermal restraint are being developed, based on the numerical calculation and validation of previously executed fire tests (Limin Lu). Further, research and experiments related to the influence of second order effects on the behaviour of concrete elements subjected to fire still has to be described by a proper analytical model. FEM based analysis, validated by previously executed real scale fire tests, are used in order to execute a parameter study with respect to second order effects under fire, enabling to propose suitable analytical models for normative purposes (Lijie Wang).
Concrete beams strengthened with fiber reinforced polymer reinforcement (FRP: Fiber Reinforced Polymer) additionally deserve a lot of attention with respect to the fire resistance. The use of FRP-concrete is currently not widely accepted due to its limited reliability during fire, making optimization of the fire resistance of FRP reinforced concrete structures an interesting research area. Specifically, the ‘Near Surface Mounted FRP’ technique where FRP reinforcement is placed in grooves near the surface of the concrete beams is evaluated (Aniello Palmieri).
A third research domain comprises the structural assessment of existing concrete structures. In this area research is being performed on an adequate and coherent evaluation procedure based on the partial safety factors and taking into account an alternative lifetime, alternative target values for the safety level and additional information, e.g. based on test data (Robby Caspeele).
The optimal bonding of concrete and reinforcement is another important research domain. Within the laboratory, experimental research is being performed on the bonding behavior of different types of reinforcing steel (Dorleta Ertzibengoa).