Computational Issues of Hinged Walls Used as Retrofitting of Existing Rc Frames

Abstract

In recent years hinged walls have been implemented as a retrofit technique for existing RC buildings. To investigate the effectiveness of the proposed solution on different frame typologies, non-linear 2D pushover analyses have been carried out. Two main configurations were adopted, representing an inner frame with weak beams and strong columns and a side frame with strong beams and weak columns, respectively. The study shows that some computational aspects are of fundamental importance in providing reliable results, namely: the dead load distribution on the beams and the moment-axial force interaction in the columns. The hinged wall technique proves to be an effective retrofit solution only if conceived properly for each structural typology; whilst in some cases it may be detrimental when applied in the traditional way. Some new configurations are herein proposed based on new connection layouts in order to be suitable for the different typologies of existing RC frames.

Pin-supported walls as seismic retrofit for existing RC frames: performance improvement through link removal

“…The simplified model can be adapted to non-shear type conditions also in the non-linear range, by defining corrective factors through sensitivity analyses. The authors showed that, in the non-linear range, the storey nodal ratio (NR) plays a relevant role in determining the structural behaviour (Casprini et al 2019). Being NR calculated for each story as the mean value of the ratios of the sum of the bending moment capacity of the beams over the sum of the bending moment capacity of the columns converging in each node, it represents an estimation of the difference from the assumption of strong beamsweak columns frame type.…”

“…A typical strong beams-weak columns existing RC frame is considered herein (frame B from Casprini et al 2019). The frame features 5-storeys and 5-bays, with an inter-storey height (H) equal to 3 m and a bay length of 4.5 m, for a total dimension of 22.5 m × 15 m. Table 3 reports the relevant details for the structural elements.…”

“…At the system capacity, the maximum bending moment in the PS wall is estimated by following the analytical procedure and then reduced by the corrective factor (Fig. 13b); by considering a mean nodal ratio of 0.87 (Casprini et al 2019) and λ equal to 0.9, the corrective factor to account for non-shear type conditions in the nonlinear range is calculated from Table 2 as 0.84.…”

“…It should be noted that an overall strength increase may also lead to higher loads on the floor diaphragms which need to be carefully assessed (Bull 2004;Rodriguez et al 2007;Tena-Colunga et al 2015;Marini et al 2022). However, the authors preliminarily investigated not only the beneficial effects, but also the weaknesses of PS wall solutions when applied in the retrofit of existing RC frames (Casprini et al 2019). It was shown that, for some frames typologies (as it will be discussed in Sect.…”