Energy dissipating devices, such as metallic ductile dampers, could represent one reliable system for seismic performance upgrading of reinforced concrete (RC) structures. This paper illustrates the significant improvement to the seismic response of RC structures equipped with dissipative bracing systems, such as eccentric braces (EBs) and buckling restrained braces (BRBs). In fact, the results of experimental tests carried out on two similar two‐storey one‐bay RC structures, respectively equipped with EBs and BRBs, are described. Referring to EBs, 3 lateral loading tests have been performed. Each test is characterized by shear links with bolted end‐plate connections. Different design criteria have been applied in the design of the connections. In the first test, capacity design criteria have not been considered. In the second test, a capacity design criterion has been applied, with a link shear over‐strength factor equal to 1.5. In the third test, a design criterion similar to the one adopted for the second test has been implemented, but with a larger over‐strength factor. In case of BRBs, two types of ‘only‐steel’ braces have been tested: one type was made using two buckling‐restraining rectangular tubes that are fully welded together with steel plates; the other type is detachable, being made again with two buckling‐restraining rectangular tubes but joined together by means of bolted steel connections. In both cases, the internal yielding core was a rectangular steel plate. The experimental results of both bracing systems are encouraging about the possibility to use these devices for improving the seismic resistance of existing RC structures. Santrauka Didinant gelžbetoninių pastatų atsparumą seisminiams poveikiams, gali būti naudojami energiją sugeriantys metaliniai slopintuvai. Straipsnyje parodoma, kaip tokios slopinančios sistemos, kaip necentriniai ryšiai ir klupimą suvaržantys ryšiai, gali iš esmės gerinti pastato seisminę elgseną. Pateikiami dviejų panašių vienos angos gelžbetoninių pastatų su minėtaisiais ryšiais eksperimentiniai tyrimų rezultatai. Tyrimai parodė, kad abi suvaržymo sistemos gerina eksploatuojamų gelžbetoninių pastatų atsparumą seisminiams poveikiams.

In this paper, after a general presentation of the Submerged Floating Tunnel (SFT) as an attractive technical solution for waterway crossings, the SFT prototype to be built in Qiandao Lake (People's Republic of China) is introduced. The main peculiarities of such an innovative system are briefly summarized and the importance of realizing a SFT prototype is underlined. The types of action that the SFTs can be generally subjected to are illustrated and the specific load conditions for the SFT prototype in Qiandao Lake are presented. The numerical analyses carried out for investigating the system behaviour in presence of the environmental loads, such as waves, currents and earthquakes, are focused. Three cables configurations are considered for the hydrodynamic analyses, in order to select the most performing one, which is subsequently analyzed also under seismic loads. The model assumptions and the results of the performed analyses are shown and critically discussed. Finally, the displacement and strength safety checks are shown, which allow to state that the designed SFT prototype is able to withstand the environmental design actions in Qiandao Lake.

Two lateral-loading inelastic tests on a real masonry-infilled reinforced concrete (RC) building are presented. The first test has been carried out on the original building. Extensive damage to both masonry panels and RC elements (columns and staircase structure) has been produced, with out-of-plane collapse of almost all the walls parallel to the loading direction. The second test has been carried out on the repaired building. Namely, perimeter masonry panels were completely rebuilt and also strengthened by placing fiber-reinforced polymer (FRP) rods into the mortar bed joints of masonry. Extensive damage was produced also during this second test. Test results are discussed and compared to each other. Besides, the ability of current analytical methods in predicting the shear strength of both unreinforced and FRP-reinforced masonry panels is investigated. Eventually, simple analytical models are proposed for the lateral response of the whole building, including also contribution from the staircase structure.

This paper presents and discusses the results of an experimental investigation on the use of composite materials for controlling the type of plastic collapse mechanism of existing reinforced concrete structures. The research has been carried out on a full-scale structure obtained starting from an existing building, which was designed and constructed at the end of 1970s. Competent authority has destined demolition of this building, which is now the subject/object of a wider experimental investigation, also briefly described in the paper. The structure has been first tested “as-is,” thus providing the control response of the original behavior. Then, it has been repaired and strengthened by means of carbon-fiber-reinforced polymers (CFRP), externally bonded in such a way to change the plastic collapse mechanism from a column-sway to a beam-sway type. Finally, the structure has been tested again in order to assess the effectiveness of the designed seismic upgrading system.