300 research outputs found
A new strategy for the seismic assessment of existing RC buildings
This paper presents a new strategy for the seismic assessment of existing Reinforced Concrete (RC) buildings. The proposed method is based on a two steps approach. A field survey of some buildings is first developed torecord their geometrical and mechanical characteristics; such survey is then enriched with information based on regulations and practical rules used during construction: the result of this step is the definition of homogeneus classes of buildings representing typical structures. The second step is based on the assessment of the seismic capacity of these structures using both refined models and parametric analysis: the outcomes can be extended to the defined classes to obtain vulnerability maps. A first application of the proposed strategy was made in Catania and the results of that study on an urban area, characterized by RC buildings constructed in the '60s and '70s without seismic provisions, are briefly presented
A new strategy for the seismic assessment of existing RC buildings
This paper presents a new strategy for the seismic assessment of existing Reinforced Concrete (RC) buildings. The proposed method is based on a two steps approach. A field survey of some buildings is first developed torecord their geometrical and mechanical characteristics; such survey is then enriched with information based on regulations and practical rules used during construction: the result of this step is the definition of homogeneus classes of buildings representing typical structures. The second step is based on the assessment of the seismic capacity of these structures using both refined models and parametric analysis: the outcomes can be extended to the defined classes to obtain vulnerability maps. A first application of the proposed strategy was made in Catania and the results of that study on an urban area, characterized by RC buildings constructed in the '60s and '70s without seismic provisions, are briefly presented
A component-level methodology to evaluate the seismic repair costs of infills and services for Italian RC buildings
The reliable estimation of seismic losses due to damage to buildings is paramount for the post-emergency management and the planning of recovery activities. For residential reinforced concrete (RC) infilled buildings, a significant role in the computation of seismic loss is played by non-structural components, above all infills, partitions and services, as shown in past earthquakes. In this work, a component-based methodology is proposed to assess seismic losses for residential RC buildings in Mediterranean region. The attention is focused on the repairing activities for masonry infills (typical enclosure or partitions elements in Italian and Mediterranean RC buildings), and for services (plumbing systems, electric equipment, floor/wall tiles…), commonly enclosed within the infill panels for the considered building typology. The described methodology can be used starting from the expected damage level to infills and partitions. It adopts given repair unit costs at different damage states of infills. The loss estimation methodology has been, first, validated by comparing predicted and actual repair costs for specific case-study buildings damaged by L’Aquila (Italy) 2009 earthquake. Then, the methodology has been applied to a wide dataset of RC buildings (about 2500 residential buildings) damaged by L’Aquila earthquake available from the literature, to show its possible application at a large-scale level. A good agreement between observed and predicted costs is obtained both for specific case-study buildings and for the wider building stock, especially when damage to structural components is very limited
Seismic Loss Estimation in Pre-1970 Residential RC Buildings: The Role of Infills and Services in Low–Mid-Rise Case Studies
The lessons learned after recent earthquakes have highlighted the key role played by infills and services in damage and loss of Reinforced Concrete (RC) buildings. Their influence in seismic performance and loss estimation of selected RC building case studies is thoroughly analyzed here. The case study selection aims to be representative of existing buildings built in Italy before 1970, and covers a different number of stories and design typologies. The seismic responses of the case-study buildings are numerically analyzed by means of non-linear static pushover analysis (PO) considering a lumped plasticity approach with a quadri-linear flexural response for beam/column elements (properly calibrated for RC elements reinforced with plain bars) and a tri-linear compressive-only axial response with diagonal concentric struts for infill panels (empirically derived from experimental data on hollow clay masonry walls). Economic loss estimation is carried out via a component-based methodology that relies on the main repairing activities and resultant costs required for the refurbishment of infills and services for different damage levels. Accordingly, a damage analysis is performed herein, given the intensity measure, based on a comparison between Interstory drift demand from PO analysis and drift-based fragility functions specific for masonry infills. Loss curves, relating the total building repair cost to peak ground acceleration (PGA), are presented and compared for the analyzed case study buildings to show their trends and quantify the incidence of infills and services with respect to the reconstruction cost. A comparison between these outcomes and those recently found in the literature emphasizes the robustness of the considered approach and the reliability of the hypotheses about damage and loss assessment
RINTC-E: Towards seismic risk assessment of existing residential reinforced concrete buildings in Italy
The RINTC research project (RINTC Workgroup, 2018), financed by the Italian Department of Civil Protection, is aimed at evaluating the seismic risk of buildings conforming to the Italian building code. Within the framework of this project, the attention has been recently focused on existing buildings, too. In this study, case-study structures, representative of the existing residential reinforced concrete (RC) building stock in Italy, are analyzed. These structures are three-storey buildings with compact rectangular plan, and they have been defined through a simulated design process, in order to represent two types of buildings, namely designed for gravity loads only during 1970s (gravity load designed, GLD) or for moderate seismic loads during 1990s (seismic load designed, SLD). GLD buildings are assumed to be located in three different sites, namely Milan, Naples and Catania, in increasing order of seismic hazard. SLD buildings are assumed to be located in L'Aquila. The assumed design typologies are consistent with the seismic classification of the sites at the assumed ages of construction. The presence of typical nonstructural masonry infill walls (uniformly distributed in plan as external enclosure walls) is taken into account, assuming three configurations along height, namely “bare” (without infills), uniformly infilled and “pilotis” (without infills at the bottom storey) buildings. Two (not code-based) Limit States are investigated, namely Usability-Preventing Damage, corresponding to an interruption of the building use, and Collapse. RC elements are modelled with a lumped plasticity approach, through an empirical-based macromodel. The possible occurrence of shear failures in columns is taken into account through a preliminary classification of the expected failure mode (flexure- or shear-controlled, in the latter case prior to or following flexural yielding) and, if needed, a modification of the backbone of the nonlinear moment-chord rotation response, through empirical models providing the expected deformation capacity at shear and axial failure, the latter meant as the (initiation of) loss of axial-load-carrying-capacity. The nonlinear response of beam-column joints is modelled, too, with a “scissors model” based on concentrated springs representing the nonlinear response of the joint panel, at the intersection of beams' and columns' centerlines, through a preliminary evaluation of the expected failure mode (i.e. prior to or following yielding of adjacent beam/column elements). Materials properties are provided by literature studies, consistent with the age of construction of the buildings. The in-plane response of infills is modelled, taking into account the presence of openings, too. Modeling should be considered as simplified and, from some points of view, still preliminary, since advances are foreseen within the project in order to capture further failure modes that can occur in structural and nonstructural elements of older, nonductile RC buildings. Nonlinear static analyses, allowing to identify the (top) displacement capacity at the investigated Limit States, are carried out. Multiple stripe nonlinear time history bi-directional analyses of the three-dimensional structural models are carried out in order to evaluate the demand, for ten stripes - each corresponding to a return period ranging from 10 to 105 years - and for twenty couples of records for each stripe. Records were selected, within the activities of the research project, based on a Probabilistic Seismic Hazard Analysis at the sites of interest for the selected return periods. Results are illustrated, highlighting the role of a - although obsolete - seismic design in the response of the buildings and in their capacity, more specifically in terms of displacement capacity at Collapse, but also in terms of demand estimated from multiple stripe analyses. Finally, demand-to-capacity ratios at the investigated Limit States are analyzed, which allow, within the scope of the project, the assessment of the seismic risk of the case study structures
Generalized FAST approach for seismic assessment of infilled RC MRF buildings: application to the 2011 Lorca earthquake
A generalized formulation of FAST vulnerability method for Reinforced
Concrete Moment Resisting Frame (RC-MRF) buildings with non-uniform
distribution of masonry infills in elevation is presented. This method belongs to
the wider family of spectral-based methodologies. It was already proposed for
uniformly infilled frames, and then applied to different earthquakes
for benchmarking purposes. The new generalized approach allows us to consider
a reduction of the amount of infills at the ground floor. Thus, this new version of
FAST is capable of computing all intermediate situations between the opposite
cases: uniformly infilled and pilotis (no infills at ground storey) MRF. Finally,
this generalized FAST method is applied to the case of the Lorca (Spain) 2011
earthquake, using parameters according to the local construction practice of the
area. Results show a fair agreement with damage survey data.GĂłmez-MartĂnez, F.; Perez-Garcia, A.; De Luca, F.; Verderame, GM. (2014). Generalized FAST approach for seismic assessment of infilled RC MRF buildings: application to the 2011 Lorca earthquake. WIT Transactions on the Built Environment. 141:427-443. doi:10.2495/SUSI140371S42744314
Recommended from our members
SV40 and Cellular Gene Expression in the Maintenance of the Tumorigenic Syndrome
The end point of the study of viral transformation is a greater understanding of the mechanism of host growth control. At present, this mechanism is totally unknown. Therefore, we are currently left with the task of tabulating the response of the cell to viral tumorigenic transformation. Such work provides a necessary context for any future hypotheses on the mechanism of cellular growth control, since such hypotheses will have to explain these responses. Fortunately, tumorigenic transformation correlates well with a relatively small number of phenotypic changes in the transformed cell. In rat fibroblast lines transformed by SV40, these changes tend to occur coordinately, forming a syndrome (Fig. 1) (Risser and Pollack 1974; Barett and Ts'o 1978; Pollack and Kopelovich 1979; Steinberg et al. 1979)
Testing analytical models for assessing the out-ofplane capacity of infill masonry walls
The influence of masonry infills on the seismic behaviour of reinforced concrete buildings has been widely studied in terms of their strength and stiffness contribution in the in-plane direction while less studies have been carried out on their response in their out-of-plane (OOP) direction. OOP collapses were observed on recent earthquakes motivating experimental efforts to characterize this behaviour combined and not with previous damage due to in plane loading demands. The present paper pretends to compare the test findings of two different experimental campaigns carried out on full-scale and scaled infill masonry panels under out-of-plane load. The main results of both experimental campaigns will be detailed and discussed to evaluate the key parameters that governed the infill
panels OOP behaviour. The results will be presented in terms of force-displacement envelopes, energy dissipation and failure modes. Besides that, the second main goal of the manuscript is to present the comparison of the experimental results with the analytical models available in the literature
- …