Due to advancements in computational tools, performing a full nonlinear response history analysis of structures at the system level using detailed numerical simulations of components has become less ...demanding, even on standard personal computers. However, the modelling approaches need to be calibrated and verified against experimental measurements to ensure the accuracy of the system-level predictions. In this study, an advanced numerical simulation method is used to predict the 3D nonlinear dynamic response of a four-story reinforced concrete building tested at E-Defense shake table. The structure is modelled in the finite element analysis programme DIANA, using a previously developed and validated approach to predict the failure modes of doubly reinforced walls with confined boundary regions. Curved shell elements are used to model the walls and slabs, and the reinforcement is modelled using embedded bar elements. The frame elements are modelled using beam elements with the effect of confinement on the concrete behaviour represented in the material constitutive model. The numerical versus experimental response comparison is conducted at both local and global levels. For local levels, the base shear versus top displacement curves, strain gradients as well as the crack pattern predicted by the numerical model are compared with the test measurements. The inter-story drift response history is considered as the metric for the global level assessment. The effects of different modelling parameters on the accuracy of predictions are also investigated.
●Development of a detailed yet feasible finite element modelling approach for nonlinear response prediction of RC buildings.●Verification of the model using full-scale shake table test of a four-story RC wall building.●Sensitivity analysis of the nonlinear response prediction to different modelling parameters.●Evaluation of the prediction accuracy with respect to local and global response parameters.●Recommendations regarding an optimum modelling approach that would result in fairly accurate predictions with reduced simulation complexity.
•A method for predicting progressive collapse resistance of RC building structures is presented.•A beam hinge with lowest curvature ductility was chosen as the critical hinge.•The ultimate flexural ...capacity is determined by yield-line analysis.•This method is validated by 12 beam-slab sub-assemblage tests.•It shows continuity of beam bottom reinforcement can mitigate progressive collapse.
Progressive collapse resistance of reinforced concrete (RC) building structures can be assessed by sudden column loss scenarios. Penultimate column loss is among the most critical scenarios since it leaves the affected beam-slab systems with lack of external lateral restraints. Under such accidental situation, flexural action in the double-span beams and slabs bridging over the removed column is experimentally identified as the main mechanism to redistribute the gravity loads, which is amplified by double span effect and dynamic effect. This paper presents a simplified approach for progressive collapse assessment of RC building structures subjected to a penultimate column loss. The collapse resistance is calculated based on an idealized elastic–plastic static response of a double-span beam-slab structure, which is constructed with (i) ultimate flexural capacity of the beam-slab structure that is determined by yield-line method of analysis and (ii) displacement ductility at the removed column position that is established based on curvature ductility of a critical connection touching on the affected area. The idealized static response is validated by experimental results of 12 beam-slab sub-assemblage tests. A simple step-by-step procedure together with worked examples are provided. Practical application of this approach and design recommendations for mitigating progressive collapse are discussed.
To explore the vulnerability of a reinforced concrete girder bridge and reinforced concrete building during an earthquake, and to compare the difference in the seismic capacity of the two types of ...engineering structures, the nonlinear vulnerability numerical and probabilistic model analysis methods were combined. Overall, 1069 reinforced concrete girder bridges and 949 reinforced concrete buildings damaged in the Wenchuan earthquake of May 12, 2008 were selected for vulnerability analysis. The vulnerability grades of damaged samples were evaluated according to the Chinese seismic intensity scale (CSIS-08), and the vulnerability matrix of reinforced concrete girder bridges and reinforced concrete buildings in multiple intensity regions was established. Moreover, the novel vulnerability comparison curve model was developed by considering the failure ratio and exceeding probability. The anomaly characteristics of seismic damage vulnerability between reinforced concrete girder bridges and reinforced concrete buildings under the influence of age, seismic design, the coupling of age and seismic design, and foundation type factors were compared and analysed. By employing the matrix calculation model of the mean damage index, the matrix and curve comparison model of the mean damage index vulnerability parameters of reinforced concrete girder bridges and reinforced concrete buildings in multiple intensity zones were developed.
•A Hierarchical Bayesian updating method is proposed to account for excitation level.•The approach estimates stiffness-amplitude relationship as well as modeling errors.•It is applied for updating of ...an RC building using ambient and shaker test data.•Estimated uncertainties are propagated in predicted response time histories.•Improved confidence bounds are obtained when accounting for excitation level.
Calibrated linear equivalent models of civil structures are often used for response prediction and performance assessment. However, these models are only valid for a narrow range of excitation level for which these models are calibrated. In this paper a hierarchical Bayesian model updating approach is proposed for model calibration and response prediction of dynamic structural systems in a wide range of excitation levels where the linear equivalent stiffness of different structural components are updated as functions of excitation amplitude. The proposed approach is implemented on a two-story reinforced concrete building with masonry infills. The building, located in El Centro California, has suffered severe damage during past earthquakes. Ambient and forced vibration tests were performed on the building using an eccentric mass shaker, and its dynamic response was measured using an array of accelerometers. The modal parameters of the structure are identified under different amplitudes of vibration and the natural frequencies exhibit significant decrease at higher vibration levels. The hierarchical Bayesian model updating approach is used to estimate the probability distribution of effective stiffness of considered structural components which is characterized by the stiffness mean and covariance as hyperparameters, as well as modeling errors. To account for the effect of vibration amplitude, the effective stiffness mean is considered as a function of vibration level. A two-step sampling approach is proposed to evaluate the joint posterior probability distribution of updating parameters. The calibrated model is then used to predict time history response of the building under forced vibration which is compared with measured data. The good agreement observed from this comparison verifies the calibrated model and the proposed approach to account for the excitation level in updating process.
•Progressive collapse resistance of infilled reinforced concrete frames was studied.•A mechanics-based infill macro-model was presented and validated against past tests.•Infilled and counterpart bare ...frames were investigated by means of pushdown analysis.•The effects of infills and parametric changes in the frame geometry were evaluated.•Uncertainties in the infills were modelled and propagated through Monte Carlo method.
Despite the increasing interest in progressive collapse-resistant design and analysis of reinforced concrete buildings that was triggered by accidental and man-made extreme events occurred over the last couple of decades, only few studies, especially numerical ones, have been carried out so far on the role of masonry infill walls. Just like in the case of first earthquake engineering applications, infills are usually considered as non-structural or architectural elements and, hence, their resistance is commonly ignored, given also that current design guidelines do not provide specific indications concerning this point. Although such an assumption leads to an ease in both design and assessment of structures, it may also give rise to misleading and overly conservative results, as the presence of masonry infills may result in extra vertical resistance.
Thus, this paper presents the outcomes of a large number of progressive collapse simulations aimed at quantifying the effects of infill walls on the vertical load-carrying capacity of reinforced concrete frames for different levels of damage, thus allowing evaluation of the interaction between these structural elements and the surrounding frame for different regimes/stages of the response. To this end, a macro-model concept was first developed and its effectiveness was then evaluated by comparing numerical results to experimental data from a past test on a one-third scaled planar structure featuring full-height infill walls. After validation, the proposed model was used to predict behavioural changes in the response of infilled reinforced concrete structures as a consequence of parametric variations in the geometry of the selected prototypes. Counterpart bare frames were also analysed in order to present a twofold comparison, in terms of resistance and dissipated energy. Finally, the manuscript describes the results of a further set of analyses, in which uncertainties in the mechanical properties of the masonry infills were modelled and propagated through fibre modelling and pushdown analysis techniques.
•The corrosion process due to the erosion of chloride ions on reinforced concrete (RC) buildings is analyzed.•The influence of the corrosion on structural reliability of RC buildings is assessed.•The ...structural reliability was evaluated at the end of different time intervals.•The analyses are performed by the Monte Carlo Simulation technique and stochastic modelling of corrosion.•This study highlights the importance for structures near salt environments.
The corrosion process due to the erosion of chloride ions on reinforced concrete (RC) buildings is analyzed in this paper. The main objective of this study is to determine the influence of the corrosion on structural reliability of reinforced concrete buildings under earthquakes. It is assumed that the buildings are located in the city of Acapulco Guerrero in Mexico, and a comparison of the structural reliability when the resistance of the structural members of the buildings under earthquakes is affected by corrosion and when not is computed. In addition, the influence of concrete cover is considered. For the objective of this study, the buildings are modeled as 3D RC frames and they are subjected to several earthquake ground motion records. Furthermore, the analyses are performed by the Monte Carlo simulation technique and stochastic modelling of corrosion initiation, corrosion propagation and corrosion cracking to estimate the steel corrosion. It is shown that omitting the effect of corrosion in reinforced concrete structures can lead to erroneous estimations of the structural reliability of buildings under earthquakes.
This research gives information about the practice of concreting work in Reinforced Concrete (RC) building project in Indonesia. The study area is Padang City, which has suffered severe damages due ...to September 2009 Earthquake. The target interviewee is 100 builders who are constructing RC buildings. This interview together with observation was conducted by directly visiting the construction sites. While collecting information about the main factors which contribute to RC building quality, e.g., concrete mixing, compaction, concrete placing and curing, the information about the profile of the builders have been collected. The results show that the workers dominate the profile of builders in productive age with 30 years experiences on average. However, 90% of the builders yet experience any construction workshop. The concreting work, which is conducted by the builders, yet reaches the required standard. More than 50% of the builders produced concrete with the higher water-cement ratio, and almost 65% admitted that they add more water after concrete`s setting time is finished. There are 3common methods of concrete compaction which is used. 6% of the builders use a vibrator, 43% use the rodding method, 28% use hummer, and 8% choose to add more water to placed concrete to increase concrete workability. Meanwhile, more than 60% of the builders do not cure the placed concrete. The results show that construction practice that is conducted by the local builders is needed to be improved. The mistakes seem to be repeated over a generation since the source of learning of the builders is mainly from their senior builder (77.25%) and self-learning (2.5%). Only 7.5% that admitted they had experienced on construction workshop.
Nowadays, it is possible to capture the whole surface areas of buildings in three-dimensional point clouds using laser scanners. However, it is still challenging to find the damaged areas of the ...building data automatically. The objective of the study is to investigate the use of deep neural networks in combination with the building data captured by the terrestrial laser scanner for damage detection. The post-seismic building data for our experiments is from a structural lab. To find out what kinds of DNNs are useful for damage detection, the deep neural networks we choose are PointNet and PointNet++ (MSG, MRG, and SSG). Since innovative DNNs can only directly operate on small 3D rigid models, we transform the detection problem into a classification problem by voxelizing the whole façade before feeding into the 3D DNNs. Meanwhile, we find a pair of optimal parameters after investigating the impact of different point sizes and voxel sizes on detection results. By comparison, we perform a point-based classification by Random Forest to highlight the effectiveness of our approach.
In this study, nonlinear time‐history analyses are performed to assess the floor response spectra of bare and infilled reinforced concrete framed buildings with different number of stories and ...designed according to Eurocode provisions for different intensity levels of the seismic action. Infill walls are modeled by neglecting and by accounting for the effects of their out‐of‐plane response and of the in‐plane/out‐of‐plane interaction. To this aim, a recent out‐of‐plane response model is updated and improved.
The results of the numerical analyses are compared in order to assess, first, the different floor spectra obtained for bare and infilled buildings and, second, the effect of the in‐plane/out‐of‐plane interaction on the results obtained for infilled buildings. The main parameters influencing the shape and the amplitude of floor response spectra are investigated, namely higher vibration modes, structural nonlinearity, and damping of the secondary element. This is also performed with the support of the discussion and application of current code and literature formulations.
Based on the results of the numerical analyses, a simplified code‐oriented formulation for the assessment of floor response spectra in bare and infilled reinforced concrete framed structures is proposed. The proposed formulation may be a useful tool for the seismic assessment and safety check of acceleration‐sensitive nonstructural components.
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