This study deals with selecting optimal seismic retrofit solutions for reinforced concrete (RC) buildings. To this aim, multi-criteria decision-making (MCDM) is implemented explicitly considering ...earthquake-induced economic loss as a decision criterion. Fragility (i.e. likelihood of damage levels vs intensity measure (IM) levels) and vulnerability (i.e. likelihood of loss levels vs IM levels) relationships are derived by using three increasingly refined analysis methods: Simple Lateral Mechanism Analysis; numerical pushover; time-history analysis. A seismically deficient RC school index building, with construction details typical of developing countries, is used for illustrative purposes. Concrete jacketing, addition of concrete walls, and addition of steel braces are the considered retrofit alternatives. Intensity-based expected loss and expected annual loss are adopted in the MCDM, among other criteria, independently derived with the three analysis methods. It is shown that, given the adopted loss-analysis methodology, the ranking of the retrofit alternatives is insensitive to both analysis methods and loss metrics, even when the weight for the seismic loss criterion is high. These findings suggest that simplified methods can be effectively employed in the conceptual/preliminary design of retrofit alternatives.
This paper investigates the trade-off between simplicity (modelling effort and computational time) and result accuracy in seismic fragility analysis of reinforced concrete (RC) frames. For many ...applications, simplified methods focusing on “archetype” structural models are often the state-of-practice. These simplified approaches may provide a rapid-yet-accurate estimation of seismic fragility, requiring a relatively small amount of input data and computational resources. However, such approaches often fail to capture specific structural deficiencies and/or failure mechanisms that might significantly affect the final assessment outcomes (e.g. shear failure in beam-column joints, in-plane and out-of-plane failure of infill walls, among others). To overcome these shortcomings, the alternative response analysis methods considered in this paper are all characterised by a mechanics-based approach and the explicit consideration of record-to-record variability in modelling seismic input/demands. Specifically, this paper compares three different seismic response analysis approaches, each characterised by a different refinement: 1) low refinement - non-linear static analysis (either analytical SLaMA or pushover analysis), coupled with the capacity spectrum method; 2) medium refinement - non-linear time-history analysis of equivalent single degree of freedom (SDoF) systems calibrated based on either the SLaMA-based or the pushover-based force-displacement curves; 3) high refinement - non-linear time-history analysis of multi-degree of freedom (MDoF) numerical models. In all cases, fragility curves are derived through a cloud-based approach employing unscaled real (i.e. recorded) ground motions. 14 four- or eight-storey RC frames showing different plastic mechanisms and distribution of the infills are analysed using each method. The results show that non-linear time-history analysis of equivalent SDoF systems is not substantially superior with respect to a non-linear static analysis coupled with the capacity spectrum method. The estimated median fragility (for different damage states) of the simplified methods generally falls within ±20% (generally as an under-estimation) of the corresponding estimates from the MDoF non-linear time-history analysis, with slightly-higher errors for the uniformly-infilled frames. In this latter cases, such error range increases up to ±32%. The fragility dispersion is generally over-estimated up to 30%. Although such bias levels are generally non-negligible, their rigorous characterisation can potentially guide an analyst to select/use a specific fragility derivation approach, depending on their needs and context, or to calibrate appropriate correction factors for the more simplified methods.
•We investigates the trade-off between simplicity and result accuracy in seismic fragility analysis of reinforced concrete frames.•We consider: analytical SLaMA or numerical pushover; non-linear time-history analysis of SDoF systems or MDoF systems.•All the methods are characterised by: a mechanics-based approach; the explicit consideration of record-to-record variability.•We quantify the errors of the simplified methods with respect to the MDoF time-history analysis in estimating seismic fragility.•Such bias levels are non-negligible. Their characterisation allows calibrating correction factors for the simplified methods.
•A by-hand procedure for the non-linear capacity curve of RC wall/frame systems is proposed.•The mechanical interaction among frame(s) and wall(s) is explicitly considered.•28 case studies: different ...geometry, wall-to-frame strength ratio and plastic mechanism.•Comparison with pushover analyses shows a maximum 5% error (base shear and displacement).
A paramount step in seismic assessment of existing structures is the determination of the structural capacity. It is widely recognised that non-linear numerical approaches are arguably the most reliable tool to achieve this goal. However, reliable yet simple analytical procedures are needed to identify potential structural weaknesses and their influence on the overall capacity, to cross-check and/or interpret numerical analyses. This paper presents a novel analytical -or “by-hand”- procedure to calculate the non-linear capacity curve of RC dual wall/frame systems within the framework of the Simple Lateral Mechanism Analysis (SLaMA). The mechanical interaction among frame(s) and wall(s) is explicitly considered to calculate their base shear and overturning moment contributions. The procedure is outlined and applied to 28 case studies with different geometry, wall(s) position, wall-to-frame strength ratio and plastic mechanism. The results are compared to refined numerical pushover analyses, showing a maximum 5% error both in terms of ultimate base shear and displacement for the majority of the case studies.
U radu su prikazani rezultati istraživanja u proizvodnji soje na OPG-u Saša Jeličić i proizvodnje agropeleta na OPG-u Slađana Pandur. Kroz uporabu tehnološke karte prikazane su pravodobno i stručno ...obavljane agrotehničke operacije na OPG-u Saša Jeličić, kao i vremenska razdoblja njihovih obavljanja. OPG Slađana Pandur bavi se proizvodnjom agropeleta kao novog energenta proizvedenog od sojine slame. Iako su novi u tom području ostvaruju zavidan rezultat u samoj proizvodnji. OPG trenutno proizvodi agropelet samo za vlastite potrebe. Rezultati istraživanja na ovom gospodarstvu pokazuju kako se uspješnom suradnjom dvaju gospodarstva može ostvariti profit na obostrano zadovoljstvo te dodatan način zarade iz sekundarnog proizvoda.
The article presents the results of research on soybean cultivation on the Saša Jeličić family farm and the production of agro-pellets on the Slađana Pandur family farm. A technology map shows the timely and professionally carried out agrotechnical works on the Saša Jeličić family farm and the periods of their implementation. The family farm Slađana Pandur is engaged in the production of agro-pellets as a new source of energy from soy straw and although they are new in the field, they achieve an enviable result in the production itself. The family farm currently produces agro-pellets for their own use only. The results of the research on this farm show that with the successful cooperation of two farms, a win-win situation can be achieved and additional income can be generated from the by-product.
Istraživan je utjecaj različitih sustava obrade tla i korištenja slame kao malča te njihove interakcije na prinos i agronomska svojstva jare pšenice. Pokus je postavljen u sjeverozapadnoj Hrvatskoj ...na fluvioslu u humidnim uvjetima 2021. godine s tri sustava obrade tla (glavni faktor): konvencionalna obrada s oranjem do 20 cm u jesen i tanjuranjem u proljeće (CT), primjena kombiniranog oruđa do 15 cm u proljeće (MT), podrivanje na dubinu 35-40 cm u jesen te rahljenje kombiniranim oruđem do 15 cm u proljeće (RT). Svaki sustav obrade podijeljen je na parcele sa i bez slame kao podfaktorom pokusa. Obrada tla imala je značajan učinak (p<0,05) samo za hektolitarsku masu, dok je značajan učinak korištenja malča zabilježen za masu 1000 zrna i sedimentacijsku vrijednost. Interakcija obrade i slame pokazala je značajan učinak na sva istraživana svojstva (prinos, masa 1000 zrna, hektolitarska masa, sadržaj proteina, sadržaj vlažnog lijepka, sedimentacijska vrijednost). Prema dobivenim rezultatima može se zaključiti da se plitkom obradom (MT) ostvaruje zadovoljavajući prinos u odnosu na konvencionalnu obradu, ali je za optimizaciju kemijskih karakteristika prinosa jare pšenice potrebno testirati i druge agrotehničke mjere.
This paper presents the influence of different tillage systems and the use of straw as mulch and their interaction on yield and yield components (physical and chemical) of spring wheat. The experiment was established in northwestern Croatia on alluvial soils under humid conditions with three tillage systems (main factor): conventional tillage with plowing up to 20 cm in autumn and disc harrowing in spring (CT), use of multitiller up to 15 cm in spring (MT); subsoiling to a depth of 35-40 cm in autumn and loosening with multitiller up to 15 cm in spring (RT). Each tillage system has subplots with and without straw. The tillage factor had a significant effect (p < 0.05) only on hectolitre mass, while a significant effect of mulch use was observed on 1000-kernel weight and sedimentation value. The interaction of these factors had a significant effect on all the components studied (yield, 1000-kernel weight, hectolitre mass, protein content, wet gluten content, sedimentation value). From the short-term results obtained, it can be concluded that shallow tillage (MT) gives satisfactory yield compared to conventional tillage, but further optimization of the agrotechnical system is required to improve the chemical properties
Dynamic analysis is the best and most accurate type of analysis for accurate evaluation of structures. However, being time consuming and the need for experience in reviewing the results of this type ...of analysis, lead engineers to use traditional or adaptive pushover analyzes. In this study, after a comprehensive literature review, three existing irregular high-rise concrete structures with 15-, 20- and 25-story are modeled in 3D and the results of different traditional and adaptive pushover analyzes are compared with the more accurate results of nonlinear dynamic analysis. Also, in performing the analysis, not only the effects of the existence of masonry infill panels, but also the effects of higher modes on the structure have been investigated, simultaneously. Also, by averaging the amount of target displacement, the effect of the lateral loading pattern on the structure has been investigated. Finally, using the SLaMA method, the contribution of concrete frames and masonry infills in the bearing of forces on the structure has been calculated. Reviewing of the results shows that in performing pushover analysis, higher modes, affect the results of adaptive methods and their effects should be considered in the analysis. Also, the results of the SLaMA Method show that in high-rise structures, infill panels have different behavior in withstanding the forces acting on the structure, which should be considered in the analysis of these members.
•Masonry infill panels are being considered for both modeling and analyses.•The location of masonry infill panels is being investigated.•Comparing the findings to those of non-linear time-history ...analyses.•Adaptive Pushover analyzes are being implemented.•Taking into account the primary mode of oscillation.
In modern Pushover analyzes, as well as irregular structural forms, consideration of the effect of higher modes is critical. For this purpose and in the same direction as the companion paper, this study extends prior work by attempting to examine three available 15-, 20- and 25-story high-rise geometrically irregular concrete buildings. This study, also takes into account the effects of masonry infill panels. The examined variables include the layout of the infill panels and investigating the results of the adaptive pushover analyzes associated with each case. The results of the more precise nonlinear dynamic analysis are the reference required to review and compare pushover analysis responses, which they show a significant difference between the results and the placement layout of the masonry panels. The most important conclusion of this study is that in irregular RC structures infilled with masonry panels or walls, it is necessary to consider not only the location of the center of mass, but also the location of the center of stiffness (rigidity) of the structure, or in another words, the influence of infill panel layouts on MRF response (i.e. eccentricity between the center of mass and stiffness). Furthermore, it is necessary to consider the main mode of oscillation. Finally, as the main characteristic of this study, the outcomes of the Simple Lateral Mechanism Analysis (SLaMA) procedure show that layouts of the infill panels can play a major role in this method.
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