Fire behaviour of HPLWC hollow core slabs: full scale furnace tests and numerical modelling Annibale Luigi MATERAZZI Professor University of Perugia Perugia, ITALY Marco BRECCOLOTTI Assistant Researcher University of Perugia Perugia, ITALY Summary The preliminary results of full scale furnace tests on HPLWC prestressed hollow core slabs are presented. The results supplied useful information to tune the available procedures for the evaluation of the thermal field under fire and of the load bearing capacity. The fire endurance of the tested specimens was reduced by the phenomenon of the explosive spalling, which confirmed to be a drawback of this innovative material. Keywords: High performance light weight concrete, hollow core PC slabs, fire resistance. 1. Introduction High performance light weight concrete (HPLWC) combines three properties that are favourable for civil engineering structures: the lightness (its unit weight is approximately 19 kN/m 3 instead of 25 kN/m 3 of normal weight concrete), the relatively high strength (f ck around 60 N/mm 2 ) and the superior durability. The aforementioned characteristics make this material very suitable for use in prestressed concrete hollow core slabs where, generally, the elements self weight represent a big amount of the total load. Hollow core slabs, made of standard characteristics concrete, are commonly used in the precast concrete industry to build large floors for industrial facilities or commercial buildings where a high fire resistance is commonly needed. While in the literature is reported the favourable fire performance of the normal concrete units [1], the fulfilment of this requirement is considered by several experts as a serious problem for the application of HPLWC, because it is well known that this material is potential exposed to the phenomenon of the explosive spalling, which may seriously affect the heat propagation and the fire endurance. The assessment of fire endurance can be carried out, according to the current standards and regulations (among which we remember [2], [3] and [4]), by means of experimental and numerical methods. These latter are, generally, easier to carry out and cheaper than the other but require the knowledge of the thermal and mechanical properties of concrete and steel, data not always available in a complete form in literature. As a first step to overcome this problem, a research programme has been started at the University of Perugia. The programme of the planned investigations includes the execution of full scale furnace tests and the development of numerical model for the analytical assessment. 2. Furnace tests 2.1 General programme of the research A series of full scale furnace tests has been planned at the University of Perugia to investigate the mechanism of heat propagation in hollow core slabs made with this innovative material and to compare the numerical and the experimental load bearing capacity. The programme includes two furnace tests. During each test two slabs will be exposed to the ISO 834 thermal programme, for a total of four HPLWC hollow core slabs. In every experiment a slab will be loaded during the fire with 60% of the service load, while the other one will be left unloaded, to study its residual strength after cooling. At the present time only one furnace test has been carried out.