1,721,098 research outputs found
RECORD-TO-RECORD VARIABILITY IN THE SEISMIC RESPONSE OF RC WALLS BUILDINGS SUBJECTED TO GROUND MOTIONS MATCHED TO THE CONDITIONAL SPECTRUM
No full textIn Performance-Based Earthquake Engineering, it is often necessary to be able to estimate the response of a structure whilst accounting for various sources of uncertainty. A number of simplified procedures have been proposed whereby record-to-record variability is accounted for using empirical estimates of dispersion. It is shown herein how the calibration of empirical dispersion estimates may prove challenging due to the numerous factors that influence dispersion. An alternative simplified numerical approach is examined, in which record-to-record variability is accounted for through use of the conditional spectrum. This simplified procedure is evaluated through a comparison with results obtained from nonlinear response-history analyses. Both inter-storey drift ratio and base shear are examined, with promising initial results
DEVELOPMENT OF A SIMPLIFIED DISPLACEMENT-BASED PROCEDURE FOR THE SEISMIC ASSESSMENT OF RC WALL BUILDINGS
No full textIn regions of low or moderate seismicity there may be cases in which a rapid, simplified and conservative seismic assessment may be sufficient to demonstrate that a building satisfies certain seismic risk requirements. In recognition of this, a simplified displacement-based seismic assessment procedure, initially formulated for RC frame structures, is formulated to permit the rapid seismic assessment of reinforced concrete (RC) wall buildings. The key aspect of the procedure is the simplified evaluation of the displacement demand as the maximum spectral displacement across all periods. The displacement capacity, shear capacity and shear demand are also estimated simply, using newly developed equations that are a function of wall geometry and material properties. By adopting such formulations for the displacement and shear, the need to evaluate the period of vibration, stiffness and flexural strength of the walls is eliminated. The proposed approach is evaluated through the design and assessment of several case study buildings. Although the procedure is likely to be conservative in most cases, it is foreseen that it would be used in an initial screening process whereby a pass would require no further assessment and a fail would trigger a more detailed investigation
A comparison of force-based and displacement-based seismic design solutions for steel MRF buildings
No full textDisplacement-based design of steel moment resisting frames with partially-restrained beam-to-column joints
No full textThis article presents a method for the direct displacement-based design of steel
moment resisting frames, with specific consideration of beam-to-column joint characteristics.
The method can be used for steel frames having any type of beam-to-column joints, from rigid
and full-strength to semi-rigid and partial-strength. The plastic rotation capacity of the joints is
explicitly taken into account within the performance criteria for the design. To assess the
accuracy of the method in controlling performance, case study structures were first designed
and subsequently analysed using non-linear dynamic analysis with a set of real accelerograms.
For all cases, the mean of peak inter-storey drift demands and the mean of peak plastic rotation
demands on joints were controlled in accordance with the limits set during design. The results
obtained demonstrate that the proposed method is appropriate for the performance-based
seismic design of steel moment resisting frames with different joint typologies
Displacement-Based Simplified Seismic Loss Assessment of Steel Buildings
No full textEvaluating losses consequent to damages induced by earthquakes has become one main paradigm in seismic performance assessment. Within this context, this paper explores a simplified seismic loss assessment methodology for steel structures that utilises displacement-based assessment in place of non-linear dynamic analyses. To this end, two case studies have been considered: (i) an archetype existing single-storey non-residential building, (ii) a prototype new multi-story residential building. Comparing results obtained using the fully probabilistic and the simplified displacement-based assessment methodologies allows the benefits of the simplified method to be highlighted. Possible difficulties encountered in applying the simplified method are also identified
Use of the conditional spectrum to incorporate record‐to‐record variability in simplified seismic assessment of RC wall buildings
No full textA procedure for incorporating record-to-record variability into the simplified seismic assessment of RC wall buildings is presented. The procedure relies on the use of the conditional spectrum to randomly sample spectral ordinates at relevant periods of vibration. For inelastic response, displacement reduction factors are then used to relate inelastic displacement demand to the spectral displacement at the effective period for single-degree-of-freedom systems. Simple equations are used to convert back and forth between multi-degree-of-freedom RC wall buildings and equivalent single-degree-of-systems so that relevant engineering demand parameters can be obtained. Consideration is also given to higher-mode effects by adapting existing modal combination rules. The proposed method is applied to several case study buildings, showing promising results in the examination of inter-storey drift ratio and shear forces. The proposed method captures the variation in the distribution of structural response parameters that occurs with variations in structural configuration, intensity, engineering demand parameter of interest and site characteristics. Discussion is provided on possible ways to improve the accuracy of the procedure and suggestions for additional future work
Comparison of force-based and displacement-based design approaches for RC coupled walls in New Zealand
Full text linkReinforced concrete coupled walls are a common lateral load resisting system used in multi-storey buildings. The effect of the coupling beams can improve seismic performance, but at the same time adds complexity to the design procedure. A case study coupled wall building is designed using Force-Based Design (FBD) and Direct Displacement-Based Design (DDBD) and in the case of the latter a step by step design example is provided. Distributed plasticity fibre-section beam element numerical models of the coupled walls are developed in which coupling beams are represented by diagonal truss elements and experimental results are used to confirm that this approach can provide a good representation of hysteretic behaviour. The accuracy of the two different design methods is then assessed by comparing the design predictions to the results of non-linear time-history analyses. It is shown that the DDBD approach gives an accurate prediction of inter-storey drift response. The FBD approach, in accordance with NZS1170.5 and NZS3101, is shown to include an impractical procedure for the assignment of coupling beam strengths and code equations for the calculation of coupling beam characteristics appear to include errors. Finally, the work highlights differences between the P-delta considerations that are made in FBD and DDBD, and shows that the code results are very sensitive to the way in which P-delta effects are accounted for.EESDThis is an Open Access article under the terms of the Creative Commons Attribution Licens
Evaluation of seismic assessment procedures for determining deformation demands in RC wall buildings
Full text linkThis work evaluates the performance of a number of seismic assessment procedures when applied to a case study reinforced concrete (RC) wall building. The performance of each procedure is evaluated through its ability to accurately predict deformation demands, specifically, roof displacement, inter-storey drift ratio and wall curvatures are considered as the key engineering demand parameters. The different procedures include Direct Displacement-Based Assessment, nonlinear static analysis and nonlinear dynamic analysis. For the latter two approaches both lumped and distributed plasticity modelling are examined. To thoroughly test the different approaches the case study building is considered in different configurations to include the effects of unequal length walls and plan asymmetry. Recommendations are made as to which methods are suited to different scenarios, in particular focusing on the balance that needs to be made between accurate prediction of engineering demand parameters and the time and expertise required to undertake the different procedures. All methods are shown to have certain merits, but at the same time a number of the procedures are shown to have areas requiring further development. This work also highlights a number of key aspects related to the seismic response of RC wall buildings that may significantly impact the results of an assessment. These include the influence of higher-mode effects and variations in spectral shape with ductility demands.EES
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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