•Frictional resistances in out-of-plane failure modes of masonry walls are evaluated.•The stabilizing role of friction is highlighted in comparison with other systems of strength.•Pushover curves are ...defined according to the displacement-based approach.•Experimental results confirm the stabilizing contribution of friction to static multiplier.
In masonry buildings without a box-type behaviour and subjected to seismic loadings, in-plane and out-of-plane failure mechanisms can take place where frictional resistances might play a predominant role. In this paper a detailed limit analysis of a simple out-of-plane failure mechanism is developed according to static force-based and displacement-based approaches. The main goal is to point out the great importance of the stabilizing role of friction between interlocked walls compared to other extrinsic or intrinsic loading capacities, e.g. the effect of tie-rods and simply supported horizontal diaphragms with frictional resistance. The sensitivity of the load multiplier to these strength parameters is investigated both at the onset of the rocking mechanism and after the hinge formation and a parametric analysis is carried out for the first condition. The results are obtained with reference to different combinations of loading conditions, including the detrimental effect of the static thrust of masonry vaults. Comparative results and pushover curves are developed to evaluate the loading and displacement capacities for each case analyzed and some experimental work is presented to validate the analytical results.
•An efficient procedure for the collapse mechanism evaluation of existing RC bridges under horizontal loads is presented.•Three different scenarios of corrosion levels are considered.•A multimodal ...pushover analysis approach is adopted.•The results obtained for the different corrosion levels are discussed considering brittle and ductile failure mechanisms.
The structural safety and durability of existing reinforced concrete bridges can be considered as one of the current most important research topics in structural engineering, especially after the numerous collapses that have occurred in recent years. Considering the Italian context, it is important to highlight that most of these structures were built in the 1960s and 1970s and, consequently, the effects of materials degradation phenomena have reduced their vertical and horizontal load-bearing capacity.
This paper presents an efficient procedure for the collapse mechanism evaluation of existing reinforced concrete motorway bridges under horizontal loads, considering the corrosion effects due to carbonation through a simplified model that takes into account the steel rebars reduction and applying a multi-modal pushover analysis approach. In this study, three different (slight, moderate and high) corrosion scenarios are considered for two existing reinforced concrete bridges characterized by frame piers. The results of the numerical analyses, which consider both brittle and ductile failure mechanisms, highlight a significant decrease of the seismic capacity of the structures as the corrosion level increases, especially for brittle collapse mechanisms that are strongly affected by the bridge maintenance condition. Such a procedure allows identifying the first structural elements reaching the collapse, providing useful information for the maintenance of existing bridges in terms of repair and strengthening interventions.
This work presents an energy-based plastic design method for steel staggered truss framing (SSTF) structures with multiple Vierendeel panels. The effectiveness of the method was investigated and the ...improved seismic performance of plastically designed SSTF structures was verified. First, parameter analysis based on a refined finite element analysis model of steel trusses with multiple Vierendeel panels was conducted. The plastic bending resistance ratio of the chord member to the intermediate vertical member was recommended based on evaluating the failure modes. Then, the energy-based plastic design procedure for the SSTF structure with multiple Vierendeel panels were described step by step. Finally, three SSTF structures were comparatively analyzed by pushover analysis and nonlinear time-history analysis, including a force-based designed SSTF structure with single Vierendeel panels, a plastically designed SSTF structure with single Vierendeel panels, and a plastically designed SSTF structure with multiple Vierendeel panels. Compared with the forced-based designed structure, the plastically designed structures showed slightly lower load-carrying capacities, but much higher ductility. The force-based designed structure had obvious soft stories, while the two plastically designed structures showed more uniform story drift distributions and formed a controllable failure mode. Compared with the structures with single Vierendeel panels, the rotation demand on the chord members of SSTF structures with multiple Vierendeel panels was significantly reduced.
•The plastic bending resistance ratio of the chord member to the intermediate vertical member was recommended.•An energy-based plastic design method for SSTFs with multiple Vierendeel panels was proposed.•Seismic behaviors of SSTFs with multiple Vierendeel panels were elaborated.
In Recent days Earthquake resistant design of structure has earned a lot of scope as Earthquake has become more common. Lateral loading behaviour and energy absorption capacity of monolithic Steel ...framed structures is significantly affected by Presence of infill which adds to the bracing of the structure, Researchers developed new methods of seismic analysis to analyse the behaviour of structure during occurrence of an Earthquake. Performance based seismic design gives methodology for accessing the performance of structure occupancy, life safety or Collapse prevention level. A non-linear static pushover analysis can be used to analyse the inelastic response of structure to lateral load or displacement. In the present research a 3D model of G + 8 story steel framed building is considered for seismic design and performance evaluation. The model was analysed using ETABS software by response spectrum method for zone V according to IS 1893–2016. The performance is accessed by Capacity Spectrum Method using non-linear pushover analysis. The result of all models are analysed and compared in terms of base shear, story displacement, pushover curve, spectrum curve, performance point of the structure. Overall performance of the structure is found in safer limits.
ABSTRACT This article presents a new proposal to estimate structural capacity models for bridge portfolios. A common approach is the use of ductility-based capacity models. Herein, a ductility ...replacement for curvature or drift as engineering demand parameters is conducted, as variability within the bridge’s classes is considered in the results and multidirectional pushover analyses are performed to assess a bi-directional load scenario. Application of the methodology is exemplified for an inventory of Northeastern Brazilian bridges. Parametric analyses are performed by varying the reinforcement ratios to estimate the capacity limit states within the range of values used. These results from probabilistic models define the capacity limit state that can be used to perform vulnerability assessment of bridges to different hazard sources, such as earthquakes.
RESUMO Este artigo apresenta uma proposta para determinação da capacidade estrutural de portfólios de pontes. Uma prática comum é o uso de modelos de capacidade baseados na ductilidade. Neste trabalho, a ductilidade é substituída por curvatura ou drift como parâmetros de demanda, uma vez que a variabilidade dos parâmetros que definem classes de pontes é considerada nos resultados e análises multidirecionais do tipo Pushover são realizadas para avaliar cenários de forças bidirecionais. Uma aplicação da metodologia é exemplificada para um inventário de pontes típicas situadas no Nordeste do Brasil. Análises paramétricas são realizadas por meio da variação das taxas de armaduras para determinação dos estados-limites dentro dos valores estudados. Os resultados dos estados limites de capacidade são informações valiosas para realização de estudos de vulnerabilidade de portfólios de pontes para diferentes fontes de ameaça, como sismos.
The design of offshore platforms in Indonesia generally uses Working Stress Design (WSD) method rather than Load and Resistance Factor Design (LRFD) method. Whereas the LRFD method produces designs ...that better describe real conditions with load and capacity factors. The load and capacity factors are obtained from consideration of the uncertainty or randomness of their values. One of the load factors used is the environmental load factor. The environmental load factor of LRFD method is obtained based on environmental characteristics not in Indonesian waters. There are differences in the environmental characteristics of each water. Uncertainty of environmental loads in the offshore platforms design is wave height, current velocities, and wind speed. To get a structure designed according to the characteristics of the waters in Indonesia, an environmental load factor is needed in accordance with the characteristics of Indonesian water. To achieve that, structural reliability analysis is needed. Structures reliabilty represents the possibility of the structure's performance criteria being met which is expressed by the reliability index. The reliability index of structures designed using the WSD method used as a reference for LRFD method. In this study, reliability analysis was carried out using the reserve strength ratio value from the pushover analysis on WSD method. The reliability index of the structure model is 4.10. This value is categorized as high reliability. This results can be used as a reference to determine the environmental load factor of Indonesian water in the future.
•Inclined loading of a re-entrant honeycomb structure induces a macro deformation stage.•New deformation stage consists of micro plateau-densification micro stages.•Increasing the loading angle ...causes the localisation of deformation.•Inclined loading causes a more compliant and ductile response.
The present study focuses on the deformation mechanisms of re-entrant honeycomb auxetic structures under inclined loading. An auxetic finite element prototype is compressed by a rigid plate during a static Riks analysis. Analysing the deformation response of the structure has revealed that a new transitional deformation stage emerges that highly restricts the elastic response. This new macro stage consists of consecutive micro stages of plateau-densification (yielding-hardening) that corresponds to a highly localised deformation mode, and alters the mechanical response in the following macro stages.
For the assessment of the seismic vulnerability of a historical building, knowledge is a fundamental prerequisite for a reliable assessment of the current seismic safety and for the choice of an ...effective action of improvement. Nowadays, thanks to the available technology used in the field of architectural surveying, laser scanning and digital photogrammetry, it is possible to define the exact geometry of any case study. The main aim of the research is to highlight the relationship between the architectural survey, performed using 3D laser scanner methodology, and the structural analysis based on the finite element method (FEM). The case of study consists of an important and unique construction, which is the baptistery of San Giovanni in Tumba (Italy). After data acquisition, developed by using optical 3D measurement techniques, the proposed procedure sought to generate a NURBS model starting from very dense outlines obtained by point cloud slices. Subsequently, the analysis was developed in a nonlinear framework, in which the behavior of the structure under seismic loads is investigated. In particular, the modal characteristics of the structure allow the use of a nonlinear analysis based on the pushover methodology. In addition, structural behavior has been analyzed by means of a nonlinear response history analysis, in which consistent ground motions were adopted to reproduce seismic loads.
