Static Procedure Research Articles

Linear static analysis of multi storey building with horizontally asymmetric architectures

Multi-storey reinforced concrete (RC) frames with horizontally asymmetric architecture are very common these days due to rapid urbanisation and scarcity of land. Site dimensions, architectural requirements and sometimes client requirements generally force the designer to adopt buildings with horizontally asymmetric architecture. So there is a need to study the seismic effect on buildings with horizontally asymmetric architecture. The objective of this study is to evaluate the performance of buildings with horizontally asymmetric architecture located in the city of New Delhi (Zone 4) and subjected to earthquake. Manual analysis results for a typical ten floor building were compared with those obtained by STAAD.Pro. to validate the Linear static analysis procedure of STAAD.Pro. One regular building and four irregular buildings of same base area and same spacing of columns with heights of 15 m, 30 m and 45 m are analysed and compared for this study. For 5, 10 and 15 floor RC frames considered for study, it is observed that frames with horizontally asymmetric geometry − 2 result in least vales of Axial force in columns and Bending moment in beams with respect to the regular (R) and other horizontally asymmetric geometries I1, I3 and I4.

Studies on Seismic Performance of Low, Medium and High Rise Reinforced Concrete Frame with Infill

This paper studies the pushover analysis of Low, Medium and High Rise Reinforced Concrete (RC) frame with infill. Pushover analysis is nonlinear static procedures for the seismic assessment of Low, Medium and High Rise Reinforced concrete (RC) structures, due to its simplicity, efficiency in modelling and low computational time. Four storey, Eight storey and Twelve storey RC frames with infill models were considered in this analysis. This pushover analysis was carried out for default hinge properties available in program based on FEMA 356. The seismic performance of RC frame with infill was measured in terms of base force and displacement curve, performance point, number of plastic hinges at different performance levels.

Формування соціально-інституційного конструкту цифрової дипломатії

Формування соціально-інституційного конструкту цифрової дипломатії

Estimation of Seismic Expected Annual Losses for Multi-Span Continuous RC Bridge Portfolios Using a Component-Level Approach

ABSTRACT A method for the estimation of expected annual losses under seismic action, using a component-level approach, is proposed. The method follows the general steps of current Performance-Based Earthquake Engineering approaches and two distinct alternatives are evaluated depending on how the collapse cases are identified. Results are compared with a commonly implemented structure level approach, showing that the latter presents an upper bound in loss estimation. The accuracy of simplified structural analysis alternatives, such as nonlinear static procedures, is also evaluated. The method is found to be suitable for economic loss assessment under seismic hazards, producing performance measures easy to understand for different decision makers.

Influence of Riverbed Scour on the Performance of Bridges Subjected to Lateral Seismic Loads

ABSTRACT Many bridges in seismic prone regions suffer from serious foundation exposure caused by scouring of the riverbed. In this study, the seismic performance of a bridge at various scour depths is assessed using a nonlinear static procedure based on the capacity spectrum approach. The performance limit of the bridge is identified in the capacity spectrum. The level of seismic intensity, characterized as peak ground acceleration, required to reach this performance limit is determined accordingly. The influence of riverbed scour on the seismic performance of a bridge is assessed by comparing the seismic intensities correlated to the performance limit at different scour depths. Results emphasize that for a bridge originally equipped with sufficient foundation strength, an improved seismic performance is observed when the scour depth is shallow. Once the scour depth exceeds a critical level, the seismic performance of the bridge is controlled by unexpected damage in the foundation. The seismic intensities correlated to the performance limit of the bridge decreases, and the seismic performance declines rapidly when the scour depth increases. The influence of structural properties and soil profile type on the seismic performance of a bridge at different scour depths is also investigated. The minimum scour depth, which causes the difference in seismic performance limit of a bridge from the original design, reduces with a decrease in the superstructure mass or soil-foundation system strength. The findings of this study help engineers evaluate the need for foundation retrofitting, particularly to ensure satisfactory seismic performance for bridges that undergo riverbed scour.

Seismic design and assessment of steel-concrete frame structures with welded dissipative fuses

This research presents the design and numerical assessment of composite steel-concrete frame structures with welded dissipative fuses. The assessment has been carried out based on linear response spectrum, nonlinear static pushover and time history procedures. The analytical expressions which define the envelope of the nonlinear response of the dissipative fuses are first presented and calibrated against experimental results available in literature. The assessment is then carried out according to a design methodology proposed herein. Outcomes of the numerical assessment indicate that the use of welded dissipative fuses successfully limited damage within the replaceable parts. Furthermore, although structures with dissipative fuses present lower strength and, generally, lower displacement capacity, their displacement ductility and global dissipative performance are generally higher than conventional structures, especially when the structure with dissipative fuses presents a dissipative configuration adjusted to the bending moment distribution diagram calculated for the applied seismic action.

FORECASTING EUROPEAN UNION CO2 EMISSIONS USING AUTOREGRESSIVE INTEGRATED MOVING AVERAGE-AUTOREGRESSIVE CONDITIONAL HETEROSCEDASTICITY MODELS

In the past few decades, there are lot of discussions around global warming and climate change primarily due to the increased CO2 emissions generated by the consumption of fossil fuels, such as oil and natural gas. After an enormous effort, the EU-28 managed to reduce CO2 emissions in 2014 by 25.7% comparing to 1990 (Kyoto Protocol). This effort should continue in the future so that the EU-28 achieve a 40% reduction on CO2 emissions by 2030. The current paper aims at investigating the optimum model to forecast CO2 emissions in the EU-28. To achieve this aim an ARIMA(1,1,1)-ARCH(1) model was used, combined with the linear ARIMA model and the conditional variance of the ARCH model. The estimation of parameter optimisation of ARIMA(1,1,1)-ARCH(1) model was done with the Maximum Likelihood approach using the Marquardt (1963), and Berndt-Hall-Hall-Hausman (BHHH) algorithms and the three distributions (Normal, t-Student, Generalized error), whereas for the estimation of the covariance coefficient the reversed matrix by Hessian was used. Finally, in order to forecast the ARIMA(1,1,1)-ARCH(1) model, a dynamic as well as a static process was applied. The results of the forecasting revealed that the static procedure provides a better forecast comparing to the dynamic one.

Seismic Assessment of Asymmetric Single-storey R/C Buildings by Two New Methodologies: Enforced Displacement-Based and Forced-Based Pushover Procedures

?wo new documented non-linear static (pushover) procedures on asymmetric single-storey R/C buildings are presented in detail herein, aiming directly at the Near Collapse state. Both procedures apply relative to the “Capable Near Collapse Principal reference system” of the single-storey building. The main objective of the two proposed procedures is to fully consider the coupling between torsional and translational vibrations of the floor-diaphragm under translational seismic excitation of the building’s base. The first pushover procedure, which is a Direct Displacement-Based one, uses floor enforced-displacements as action. In the second pushover procedure, which is a Force-Based one, the floor lateral static forces are applied eccentrically to centre of mass using suitable inelastic design eccentricities (dynamic plus accidental ones). The floor enforced-translations/rotation and the appropriate inelastic dynamic eccentricities used in the two proposed procedures derive from extensive parametric non-linear response history analysis and are given by figures or equations. In order to clarify in detail and evaluate the new pushover procedures, a torsionally-flexible, double-asymmetric, single-storey R/C building is seismically assessed. The validation of both procedures relative to the results of non-linear response history analysis shows that both predict with safety the in-plan displacements of the building.

Linear static procedures for the seismic assessment of masonry buildings: Open issues in the new generation of European codes

Linear procedures (lateral static force method or modal response spectrum analysis) are the standard approach for the seismic design of new structures. On the contrary, nonlinear procedures, in particular incremental pushover analysis, should be used for the seismic assessment of existing buildings, because it is difficult to estimate the behavior factor of a building in the absence of a standardized capacity design. Moreover, in the case of existing buildings, the use of linear procedures provides results that are excessively conservative, therefore unreliable. Despite this, seismic codes consider linear procedures because of their theoretical simplicity and robustness with respect to model uncertainties and non-linear issues, a priori avoiding convergence problems. The paper deals with the critical issues related to the application of linear static procedures for the seismic assessment of masonry buildings. Methods proposed by the present draft of the Eurocode 8 (Part 3) and the new Italian Seismic code (NTC 2018) have been applied to a case study building, under two configurations (regular, irregular); in particular, the modelling options usually adopted by professionals have been considered. Results are compared with the assessment carried out through the nonlinear pushover analysis, which may be assumed as able to better estimate the actual seismic behavior. Anyhow, the aim of the paper is not a validation of the code procedures but a comparison between alternative allowed methods. Conclusions show that even by considering the recent improvements in the codes, in the regions characterized from medium to high seismic hazard, linear methods result almost inapplicable leading to almost all buildings not verified in contrast with the evidences of most recent earthquakes.

Development of Fragility Curves for Single-Column RC Italian Bridges Using Nonlinear Static Analysis

ABSTRACT The main objective of this study is to assess the accuracy and suitability of Nonlinear Static Procedures (NSPs) in the development of analytical damage fragility curves for seismic risk assessment of large portfolios of Reinforced Concrete (RC) bridges. Seven NSP approaches, from widely used single-mode conventional pushover-based approaches to the more rigorous multi-mode conventional or adaptive pushover-based procedures are implemented. By systematically comparing fragility curve estimations in terms of shape and accuracy in predicting mean annual rates of exceeding predefined damage limit states, results indicate that when bridges can be classified as higher mode sensitive, multi-mode-based approaches offer a powerful alternative to rigorous time history analysis. In particular, Generalized Pushover Analysis and Adaptive Capacity Spectrum methods offer a better performance with respect to other multi-mode alternatives. For first mode dominated bridges, with a classical first mode shape, the performance of all methods is similar. Single-mode based procedures present an acceptable alternative only in such particular cases, for which the N2 method represents a viable approach when compared to other single-mode or multi-mode procedures.

Parametric Assessment of Equivalent Static Procedure Accounting for Foundation-Pinning Effects in Analysis of Piled Bridge Abutments Subject to Lateral Spreading

AbstractFoundation pinning is a critical consideration for design and analysis of bridge foundations subject to liquefaction-induced lateral spreading, particularly for bridges with a standard appr...

Damage assessment of reinforced concrete moment resisting frames using performance-based seismic evaluation procedure

The performance-based seismic design has two primary concerns: (a) appropriate quantification of the uncertainties associated with the performance evaluation process, and (b) satisfactory characterization of the associated structural damage for direct incorporation into the design or performance evaluation methodology. This study deals with seismic damage assessment of moment resisting frames. Some damage indicators are introduced by using the nonlinear responses obtained at the output of nonlinear static procedures. Among these, some are possible extensions of previously defined static indicators and some are newly defined ones. The damage variables used in formulation are inelastic displacement, spectral displacement, spectral acceleration, and base shear. The introduced damage indicators address the plastic ductility, loss of strength, stiffness degradation, and dissipated energy of a structure. The variations in damage values for various drift criteria were used to associate with different performance levels.

Performance-based Seismic Assessment of Reinforced Concrete Moment Resisting Frame

The performance-based seismic design has two primary concerns: (a) appropriate quantification of the uncertainties associated with the performance evaluation process, and (b) satisfactory characterization of the associated structural damage for direct incorporation into the design or performance evaluation methodology. This study attempts to address these primary concerns by evaluating the performance of reinforced concrete frame using nonlinear static procedures. For this, fifteen-moment resisting frames designed following the guidelines of Indian seismic codes were subjected to different lateral load patterns. The seismic performance is investigated in terms of fundamental periods, roof displacements, interstory drift ratio, base shear, and modification factor and was compared with various performance limits. The obtained results showed disagreement with Indian seismic code provisions, especially, towards the fundamental time period, upper and lower bound values of base shear drift ratio and modification factor.

Investigating the lateral stability of three-wheeled scooter taxi due to tyre-road forces

Three-wheeled scooter taxi (TWST) that is currently prevalent in developing countries, is fuel efficient and cheap. It is used mainly for commercial purposes, also as a means of reducing unemployment and tackling poverty. However, the vehicle is unstable and prone to accidents due to its design configuration. The aim of this research work is to investigate the lateral stability of TWST due to Tyre-Road Forces. Therefore, lateral stability equations for three-wheeled vehicle (TWV) were developed and used in the analysis of TWST based on parametric values obtained from static test. The results showed that the vehicle is stable with respect to lateral stability, which is in line with what was obtained from literature, thereby validating the models with the driver alone. However, with two or more occupants the vehicle became unstable. Possible ways of eliminating this instability were discussed. The static test procedure, if adopted and legislated upon, would significantly enhance safety of life and properties of stakeholders in developing countries.
 Keywords: Three-wheeled scooter Taxi, Stability Analysis, Safety of life and properties, Legislation.

Preparation and Characterization of Anionic Composite Hydrogel for Dyes Adsorption and Filtration: Non-linear Isotherm and Kinetics Modeling

An anionic, low-cost, and environmentally friendly composite PVA/Agar/Bentonite (PAB) hydrogel was prepared via self-assembly method, then evaluated as an adsorbent for both cationic methylene blue (MB) and anionic Congo red (CR) dyes using static (batch adsorption) and dynamic (column filtration) procedures. The structural/textural and morphological features of the hydrogel were investigated by X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, zeta potential measurements and scanning electronic microscopy. The nonlinear forms of first-order and second-order kinetic model, and nonlinear forms of Langmuir–Freundlich, Redlich–Peterson, Langmuir and Freundlich isotherm model were used to study the equilibrium adsorption. The adsorption kinetics of MB and CR dyes onto composite hydrogel followed the nonlinear form of pseudo-second-order model with the adsorption capacity of 107.45 and 42.05 mg/g, respectively. The equilibrium data were fitted well to the nonlinear Langmuir–Freundlich model for MB dye and nonlinear form of Langmuir model for CR dye, which were confirmed by R2, MSE and EABS values. Using the column purification method, the composite hydrogel PAB promotes the removal of the MB and CR pollutants by maintaining the concentrations of the filtrate solutions below 0.1 mg/L, even when the volume of the dye reaches 20 mL.

A multi-mode adaptive pushover analysis procedure for estimating the seismic demands of RC moment-resisting frames

The main contribution of this paper is to develop a new multi-mode adaptive pushover analysis procedure for estimating the seismic demands of RC moment-resisting frames. The proposed procedure enhances the seismic demands of conventional pushover analysis methods by combining the advantages of ‘multi-modal’ and ‘adaptive’ pushover procedures. The presented method, which has been named the multi-mode adaptive displacement-based pushover (MADP) analysis procedure, estimates the seismic demands of buildings by using several multi-stage modal pushover analyses. Each multi-stage pushover analysis begins with the lateral load pattern proportional to the elastic mode-shape. The pushover analysis is then continued with a new lateral load pattern, constructed based on the story displacements obtained from the previous stage. The lateral force distribution is changed whenever a new plastic hinge is formed in the inelastic structural model. The ‘first-mode’ inelastic mode-shape of the structure is also used by the MADP method to accurately estimate the value of the target-displacement. The final structural responses are determined by combining the seismic demands obtained by the multi-stage modal pushover analyses using an appropriate modal combination rule. The accuracy and efficiency of the MADP procedure is verified using the analysis of four special RC moment-resisting frames with 4-, 8-, 12-, and 20-stories. The structural responses are estimated for two different seismic hazards (intensities). A comparison is then carried out between the estimates from the MADP method with those given by the exact nonlinear response history analysis (RHA). The results from two advanced pushover analysis procedures including the modal pushover analysis (MPA) and consecutive modal pushover (CMP) methods are also presented for the purpose of comparison. The results show that the MADP method is able to satisfactorily estimate the critical seismic demands such as interstory drift ratio and the plastic rotation of the hinges for the example buildings, and to provide an advanced nonlinear static procedure for the seismic performance assessment of RC moment-resisting frames.

Static force-based seismic analysis of reinforced concrete frames having weaker beam-column joints

Shake table tests were conducted on three 1:3 reduced scale two-story RC frames having weaker beam-column joints. The models were subjected to multi-levels input acceleration time histories to understand the seismic behaviour of test models. The models incurred severe damages in beam-column joint panels, forming shear hinging in joint panels, and were found in the incipient collapse state under input excitation below the design level excitation. Elastic hypothetical structures were considered having fundamental frequency that of test structures, which were subjected to actually recorded input excitation, in order to assess the seismic demands (base shear force and lateral roof displacement) using simplified analytical static procedure. The analytically predicted demands were correlated with the measured inelastic response, in order to calculate seismic response parameters (force reduction factor R and displacement modification factors Cd ). On average, R = 2.0 and Cd = 1.86 were obtained for the considered structures. The derived seismic response parameters can be employed in the analytical static force-based procedure for the seismic vulnerability assessment of RC frame structures having weaker beam-column joints. Example study is presented for the vulnerability assessment of considered structure using the proposed analytical static force procedure and the derived seismic response parameters.

Orbicularis Oculi Muscle Reinnervation Confers Corneal Protective Advantages over Static Interventions Alone in the Subacute Facial Palsy Patient.

Corneal protection is a priority in flaccid facial palsy patients. Denervation of the orbicularis oculi muscle results in weak palpebral closure and predisposes patients to severe corneal sequelae. While periorbital static procedures enhance corneal coverage in repose, voluntary closure is only regained through dynamic reinnervation of the muscle. This study aims to elucidate the added effect of dynamic reinnervation of the orbicularis oculi muscle on long-term corneal integrity as well as on dynamic closure of the palpebral aperture. Retrospective review was performed on two groups of complete palsy patients: those who received solely periorbital static procedures and those who underwent concomitant orbicularis oculi muscle reinnervation and static lid procedures. Only patients with complete ophthalmic examinations were included. Corneal punctate epithelial erosions in addition to static and dynamic palpebral measurements were serially assessed preoperatively and postoperatively. Of 272 facial palsy patients, 26 fit the inclusion criteria. Eleven patients underwent combined muscle reinnervation involving facial-to-masseteric nerve coaptation in addition to static eye procedures, and 15 patients underwent solely static interventions. Analysis revealed a 65.3 percent lower mean punctate epithelial erosion score in reinnervation patients as compared with static patients when evaluated at more than 9 months postoperatively (p < 0.01). Reinnervation patients were also found to have 25.3 percent greater palpebral aperture closure (p < 0.05) and 32.8 percent higher closure velocity (p < 0.01) compared with static patients. In patients with subacute facial palsy, dynamic reanimation of the orbicularis oculi muscle with concomitant static interventions provides lasting corneal protection not seen in patients who receive solely static interventions. Therapeutic, III.

Individualized lung protective ventilation vs. conventional ventilation during general anesthesia in laparoscopic total hysterectomy.

Laparoscopic total hysterectomy is performed by carbon dioxide insufflation, Trendelenburg position and mechanical ventilation of patients under general anesthesia. However, this may induce pulmonary atelectasis and/or hyperdistention of the lungs. Multiple studies have indicated that mechanical ventilation with the use of low tidal volumes, moderate positive end-expiratory pressure (PEEP) and regular alveolar recruitment maneuvers may improve post-operative outcomes. However, the benefits of an individualized level of PEEP have not been clearly established. In the present study, it was hypothesized that a moderate fixed PEEP may not suit all patients and an individually-titrated PEEP during anesthesia may improve the peri-operative pulmonary oxygenation function. The aim of the present study was to compare the pulmonary oxygenation function and post-operative pulmonary complications (PPCs) in patients receiving individualized lung-protective mechanical ventilation (LPV) vs. conventional ventilation (CV) during laparoscopic total hysterectomy. The present study was a randomized double-blinded clinical trial on 87 patients who were randomly divided to receive CV or protective ventilation (PV). An optimal individualized PEEP value was determined using a static pulmonary compliance-directed PEEP titration procedure. Pulmonary oxygenation function, serum inflammatory factors, including interleukin-8 and Clara cell protein 16, the incidence of PPCs and the post-operative length of stay were also determined. Patients in the PV group exhibited improved pulmonary oxygenation function during and after the operation. The total percentage of PPCs during the first 7 days after surgery was significantly lower in the PV group compared with those in the CV group. In conclusion, as compared to CV, intra-operative individualized LPV significantly improved pulmonary oxygenation function and reduced the incidence of PPCs during the first 7 days after laparoscopic total hysterectomy (Clinical trial registration no. ChiCTR1900027738).

Pre‐ and post‐earthquake regional loss assessment using deep learning

SummaryAs urban systems become more highly sophisticated and interdependent, their vulnerability to earthquake events exhibits a significant level of uncertainties. Thus, community‐level seismic risk assessments are indispensable to facilitate decision making for effective hazard mitigation and disaster responses. To this end, new frameworks for pre‐ and post‐earthquake regional loss assessments are proposed using deep learning methods. First, to improve the accuracy of the response prediction of individual structures during the pre‐earthquake loss assessment, a widely used nonlinear static procedure is replaced by the recently developed probabilistic deep neural network model. The variabilities of the nonlinear responses of a structural system given the seismic intensity can be quantified during the loss assessment process. Second, to facilitate near‐real‐time post‐earthquake loss assessments, an adaptive algorithm, which identifies the optimal number and locations of sensors in a given urban area, is proposed. Using a deep neural network that estimates area‐wide structural damage given the spatial distribution of the seismic intensity levels as a surrogate model, the algorithm adaptively places additional sensors at property lots at which errors from surrogate estimations of the structural damage are the greatest. Note that the surrogate model is constructed before earthquake events using simulated datasets. To test and demonstrate the proposed frameworks, the paper introduces thorough numerical investigations of two hypothetical urban communities. The proposed frameworks using the deep learning methods are expected to make critical advances in pre‐ and post‐earthquake regional loss assessments.