Experimental Analysis of Steel Dissipative Bracing Systems for Seismic Upgrading

Abstract

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.

A Semi-Analytical Model for Dissipative Shear Links: Experimental Tests and Numerical Analyses

“…80 mrad) but reliable in relation to what observed during experimental tests revealing a higher rotational capacity and, besides, higher over-strength factors ( [19]- [20]- [21]). A safety/confidence factor equal to 1.30 has been also applied during the design.…”

Numerical investigation of seismic behavior of short-core all-steel buckling restrained braces

“…In addition, cyclic full scale tests on all-steel dismountable BRBs applied to an existing damaged reinforced concrete building were conducted by Corte et al [19] and Aniello et al [20]. Moreover, the effectiveness of special only-steel BRBs and also eccentric braces to enhance the seismic resistance of an existing RC building was tested by Mazzolani et al [21]. The results showed the distinct ability of all-steel BRBs to increase the lateral resistance and stiffness of RC frames and produce a stable hysteretic behavior and good ductility in the braced frame.…”

On the selection by MCDM methods of the optimal system for seismic retrofitting and vertical addition of existing buildings

“…The tested BRBs belonged to the 'only-steel' type, with the core made of one single steel plate (25 mm  10 mm) and two restraining rectangular steel tubes (100 mm  50 mm  5 mm) [6]. Two tests were carried out, differing only for some detailing of the yielding core end portions [7,8]. The first type of BRB tested is shown in Fig.…”