Volume 12 (2016): Edizione 1 (March 2016)

Using recycled concrete aggregates (RCA) is a matter of high priority in the construction industry worldwide. In countries like the Netherlands, Denmark, Germany, USA, Japan, France recycled concrete aggregates obtained from demolition are valorized up to 90%, mainly for road construction and less in the manufacture of new concrete.

Recycled concrete aggregates (RCA) generally result from a two-stage crushing of the concrete obtained from demolition followed by the screening and removal of contaminants (wood, plastic, metal, ceramics etc.). The literature review showed that the recycled aggregates concrete (RAC) are less resistant, with 15 to 40% versus concrete obtained using natural aggregates. The factors that play a role in the reducing of mechanical resistance are presented and analyzed in this study.

This paper presents a study on the use of recycled aggregates, from a concrete of specified class, to acquire new cement concrete with different percentages of recycled aggregates. In order to evaluate the influence upon the properties of the new concrete obtained, recycled aggregates have been characterized in terms of the granulosity, the granule shape, the absorption of water, behavior to the Los Angeles test, the content of attached mortar etc.

This paper discusses the concept of a hybrid damper made from a combination of two dissipative devices. A passive hysteretic device like steel Buckling Restrained Brace (BRB) can be combined with a magneto-rheological (MR) Fluid Damper in order to obtain a hybrid dissipative system. This system can work either as a semi-active system, if the control unit is available, or as a passive system, tuned for working according to performance based seismic engineering (PBSE) scale of reference parameters (i.e. interstory drift).

This study presents the results of the mathematical modelling for the micropiles foundation of an investement objective located in Slanic, Prahova county. Three computing models were created and analyzed with software, based on Finite Element Method. With Plaxis 2D model was analyzed the isolated micropile and the three-dimensional analysis was made with Plaxis 3D model, for group of micropiles. For the micropiles foundation was used Midas GTS-NX model. The mathematical models were calibrated based with the in-situ tests results for axially loaded micropiles, embedded in salt rock. The paper presents the results obtained with the three software, the calibration and validation models.

Experience of designing buildings with structural masonry walls and masonry non-structural elements using Codes CR 6-2006 [15a] and P 100-1/2006 [16a], that were developed based on design principles and rules of Eurocodes adopted in Romania SR EN 1996-1-1[13] and SR EN 1998-1[14], revealed the need of some additions and corrections of texts.

These interventions made by developing Codes CR 6 -2013[15] and P 100-1/2013[16], which we can characterize synthetically as follows:

- Are aligned with the Structural Eurocodes principles but correcting some identified deficiencies.

The communication exposes and justifies synthetically the following new approaches introduced in the 2013 editions of the two regulations:

Modification of the methodology for the partial safety factors (γ_M) and for establishing the minimum necessary strength values of masonry.