Nikola Tošić

Experimental Setup for Measuring Long-Term Behavior of Green Reinforced Concrete Beams

The behavior of reinforced concrete under long-term loading is an important topic when designing concrete structures. Creep and shrinkage of concrete and long-term deflections of concrete structures, mainly reinforced concrete beams, have been studied for many decades but because of the long-term nature of these tests, existing experiments are relatively scarce. More importantly, there are significant challenges when carrying out these tests. These include achieving optimal beam design to ensure a realistic stress distribution with a developed cracked state, measuring deflections from self-weight, adequately measuring elastic deflections and strains, and instantaneously applying the imposed load. The problem is exacerbated with the advent of sustainable structural concretes containing recycled and waste materials—green concretes; they possess specific properties and experimental results for these concretes are even scarcer.

Current Serbian design codes: Transferring from a deterministic to a semi- probabilistic approach

The Serbian design code for reinforced concrete structures is somewhat out-of-date in its approach to structural design. In this paper, a study into the possible transition to a semi-probabilistic approach is presented. Firstly, the implicit reliability indices in the current Serbian reinforced concrete design code are determined for three design situations bending, axial compression and shear and for various cases within each of them. The implicit reliability indices show that the Serbian design code is more conservative than Eurocode 2, but that design for shear without stirrups has a significantly low reliability index (2.27). Secondly, a calibration procedure was implemented in order to obtain partial safety factors for a target reliability index of 4.8 (calculated as the average of the implicit reliability indices). The obtained partial safety factors are ready-for-use with the current Serbian design code and, as expected, are higher than those in Eurocode 2.