Construction + Civil Engineering

Bossong has obtained an ETA certification (ETA – 24/0719) on the BCR HYBRID for applications on masonry under seismic action, making the product suitable for use on both concrete, medium-heavy loads, as well as on all types of masonry.

Solid masonry buildings represent a significant part of building heritage. This construction technique, which uses bricks or solid blocks bound with mortar, has been widely adopted in Italy for centuries, thanks to the availability of materials and the excellent structural properties of masonry. From ancient medieval villages to Renaissance palaces, solid masonry has made it possible to create long-lasting and resistant structures, capable of withstanding the passage of time and environmental challenges.

The main challenge for masonry buildings is to resist horizontal loads, such as seismic loads. Unlike typical concrete frame buildings, which have steel reinforcement inside the concrete element, masonry buildings generally have larger load-bearing elements but do not have reinforcement to resist tensile stress.

Precisely for this reason, reinforced walls have come into use today in the design and construction of a new masonry structure, that is, masonry blocks that are reinforced with reinforcement bars that are then incorporated into the masonry itself with mortar or binder. But what should we do with existing and historic walls? In the case of existing buildings, the interventions that are carried out to reinforce and secure the structure include consolidation and reinforcement interventions. This includes creation of a rigid and collaborating slab in such a way as to have a box type structure functioning under seismic action; creation of rigid curb connected with rigid slab; reinforcement of load-bearing masonry sections using reinforced plaster; reinforcement of the floor with the creation of a new collaborating slab; as well as the reinforcement of load-bearing walls with reinforced plaster.

All these types of interventions require the use of a steel element – adhesion bars that are embedded in the existing element in such a way as to connect the new load-bearing element with the existing one. The products used to anchor the reinforcing bars are obviously chemical anchors. Until recently, for this type of product, the ETA certification was only related to masonry fixings under static action, therefore excluding seismic loads.

Today, however, it is possible to obtain CE Marking and therefore an ETA of a product that contains, in addition to static loads, the seismic performance for solid masonry blocks only. The new version of EAD 330076 has recently been released, which includes the tests necessary for seismic qualification of solid masonry. These tests (total of 20 tests per bar diameter) are divided into shear tests and tensile tests, in a number equal to 10 tests for each type.

All tests are performed in the mortar joint, which is always assumed to be the weak element and in which a crack of 0.5mm is opened, in order to simulate the effect of an earthquake on the brick wall. Finally, half of the tests are performed by applying a static load and half by applying load cycles. The reduction in performance is then evaluated.

Bossong has obtained ETA certification (ETA – 24/0719) on the BCR HYBRID product for applications on masonry under seismic action. This qualification is added to the other ETAs already present on the product for applications in concrete (with seismic qualification C1 and C2) and applications in solid and perforated masonry under static loads.