Influence of load pattern on the shear strength of hollow core slabs in uncracked sections

Precast hollow core slabs are frequently used to cover large spans for industrial, commercial and residential buildings. Their use has been proved during many years of application to be reliable and economical. However, their construction methods, whether they are extruded or slip-formed, do not make it possible to insert shear resistant reinforcements. For this reason, there are still today significant inconsistencies between experimental data of shear strength of these elements and design strength provided for by the specific structural standards, especially for slabs of greater thickness. In this work, additional considerations, with respect to those already present in the literature, are made on the influence of applied load type (concentrated or distributed) and on the distribution modalities of the stresses upon collapse between the different webs. Detailed numerical analyses are carried out with the commercial FE code Abaqus to determine the shear strength in the uncracked bending zones and to individuate the crack pattern at collapse. The first results of the investigations indicate that the shear strengths of hollow core slabs for distributed loads are always greater (between 22.9% and 41.1% for the investigated slabs) than those observed for concentrated loads.