Hinge Properties Research Articles

Power synchronisations determine the hovering flight efficiency of passively pitching flapping wings

The power exchange between fluid and structure plays a significant role in the force production and flight efficiency of flapping wings in insects and artificial flyers. This work numerically investigates the performance of flapping wings by using a high-fidelity fluid–structure interaction solver. Simulations are conducted by varying the hinge flexibility (measured by the Cauchy number, $Ch$ , i.e. the ratio between aerodynamic and torsional elastic forces) and the wing shape (quantified by the radius of the first moment of area, $\bar {r}_1$ ). Results show that the lift production is optimal at $0.05 < Ch \leq 0.2$ and larger $\bar {r}_1$ where the minimum angle of attack is around $45^\circ$ at midstroke. The power economy is maximised for wings with lower $\bar {r}_1$ near $Ch=0.2$ . Power analysis indicates that the optimal performance measured by the power economy is obtained for those cases where two important power synchronisations occur: anti-synchronisation of the pitching elastic power and the pitching aerodynamic and inertial powers and nearly in-phase synchronisation of the flapping aerodynamic power and the total input power of the system. While analysis of the kinematics for the different wing shapes and hinge stiffnesses reveals that the optimal performance occurs when the timing of pitch and stroke reversals are matched, thus supporting the effective transfer of input power from flapping to passive pitching and into the fluid. These results suggest that careful optimisation between wing shapes and hinge properties can allow insects and robots to exploit the passive dynamics to improve flight performance.

Simplified Method for Nonlinear Seismic Response Analysis of Corroded Pile-Supported Wharf

Fiber-based finite element analysis (FB-FEA) has been widely recognized for its ability to reproduce experimental results and is also a reliable method for evaluating the nonlinear seismic response of pile-supported wharves (PSWs). Design practice often employs frame analysis (FA) due to its easy implementation. To precisely reproduce the nonlinear seismic response of PSW using FA, it is necessary to configure mechanical properties such as the hinge property correctly. However, it is unclear whether the hinge properties proposed in previous studies can be applied to PSWs with spun piles. In this study, a novel FA method was developed to investigate the nonlinear seismic response of PSWs with corroded spun piles considering PC bar area reduction, deteriorated material properties, the bending stiffness reduction factor, and the moment–curvature relationship of the spun pile. The nonlinear seismic response of corroded PSWs was determined by performing pushover analysis using three methods: FA using the method of the previous study (FA-1), the proposed FA method (FA-2), and FB-FEA. As regards PSW foundations, vertical pile and batter pile configurations were considered. The pushover analysis results were compared in terms of several parameters, such as the natural period, plastic hinge formation, and load capacity of the corroded PSWs. The FA-2 results agreed very well with the FB-FEA results, while the FA-1 results were less precise with respect to the natural periods and load capacities of corroded PSWs. The results indicated that the bending stiffness reduction factor, moment–curvature relationship, and axial load–bending moment (P–M) capacity of the corroded spun piles should be appropriately defined. Corrosion had greater negative impacts on the compressive axial load and bending moment capacities of the spun pile than on its tensile axial load capacity.

Assessment of plastic hinge length in reinforced concrete columns

Plastic hinge properties are crucial parameters in predicting the nonlinear response of structural elements. Because of the intricate material nonlinearity, precise determination of the plastic hinge length (PHL) has encountered several obstacles. Over the last few decades, there have been various definitions and models put forth to forecast this length, nevertheless, the outcomes displayed significant disparities. Therefore, the paper introduces a comprehensive method for determining PHL using certain criteria, including rebar strain profiles, concrete cover and core peak strains, curvature profiles, and damage observations. Furthermore, a set of four full-scale reinforced concrete (RC) columns measuring 400 mm × 400mm × 3000mm and featuring varying transverse reinforcement configurations were constructed and subjected to testing under a high axial load ratio (ALR). The tested results implied that it is necessary to separate the PHLs based on different criteria. The high axial compression load led to enhancing the PHLs, which were based on rebar compressive yield strains, curvature profiles, concrete cover and core peak strains. In contrast, it has a minor effect on PHL based on tensile yield strains. In addition, the amount of transverse reinforcement had an insignificant effect on all PHLs for tested columns. Hence, a revised equation was proposed to estimate the equivalent PHLs of rectangular RC columns based on tested results and a 114-column database. The proposed equation had better accuracy compared with some other model results in the literature.

Instability-Induced Origami Design by Topology Optimization

Instability-induced wrinkle patterns of thin sheets are ubiquitous in nature, which often result in origami-like patterns that provide inspiration for the engineering of origami designs. Inspired by instability-induced origami patterns, we propose a computational origami design method based on the nonlinear analysis of loaded thin sheets and topology optimization. The bar-and-hinge model is employed for the nonlinear structural analysis, added with a displacement perturbation strategy to initiate out-of-plane buckling. Borrowing ideas from topology optimization, a continuous crease indicator is introduced as the design variable to indicate the state of a crease, which is penalized by power functions to establish the mapping relationships between the crease indicator and hinge properties. Minimizing the structural strain energy with a crease length constraint, we are able to evolve a thin sheet into an origami structure with an optimized crease pattern. Two examples with different initial setups are illustrated, demonstrating the effectiveness and feasibility of the method.

Comparison of capacity curves of reinforced concrete buildings using ADINA moment-curvature element and SAP2000 lumped plasticity model

One of the most important steps in the establishment of the capacity curve using pushover analysis is setting up reasonable member nonlinear properties that control the inelastic behavior of reinforced concrete (RC) members. The length of the plastic hinge is one of the major effective parameters in such type of analysis when using lumped plasticity models. In this study, the finite element program ADINA which has the capabilities in defining the non-linear properties through the moment-curvature for element, without the need to define the plastic hinge length, was utilized to obtain the capacity curve for three RC buildings. Also, the capacity curve was obtained using the user-defined non-linear hinge properties in SAP2000 software in which the nonlinear elements are defined by assigning plastic hinges at the ends of RC members. The potential differences between capacity curves obtained using the user-defined hinge properties by SAP2000 and the moment-curvature element in ADINA were investigated. Two four-storey and one eight-storey RC frames with different ductility were considered to represent low to medium rise buildings. The results of analysis showed that the base shear capacity obtained by SAP2000 model for different plastic hinge length values were almost identical and the base shear value obtained by ADINA model was little lower than that obtained by SAP2000 models, the variation in base shear capacity ranged between 3.55% and 6.53%. However, the displacement capacity was significantly affected by the value of the plastic hinge length.

Non-linear displacement and deformation damage limits of reinforced concrete circular columns by analytical observations according to TBSC 2018

In the study, based on the non-linear calculation methods used to determine the seismic performance of structures in TBSC 2018, the stress-strain, moment-curvature, displacement capacity, plastic rotation limits, and deformation-based damage limit values of the reinforced concrete circular cross-section columns were calculated and compared according to different design parameters. The studied effects of the design parameters on the non-linear relation of reinforced concrete columns were also evaluated in terms of strength, curvature, and displacement ductility of the sections. All design parameters affecting the non-linear behavior and deformation limits of the reinforced concrete circular cross-section columns were taken into account. Deformation demands for reinforced concrete structural members are essential for detecting element damage. Based on TBSC (2018), non-linear relationships of reinforced concrete columns were obtained in order to calculate plastic hinge properties and deformation limits. For the Limited Damage, Controlled Damage, and Collapse Prevention performance levels defined for the structural elements in TBSC 2018, plastic rotation and deformation limit values were obtained according to the characteristic values calculated from the non-linear analyzes of reinforced concrete circular columns. For column models, damage limits and damage zones calculated based on TBSC 2018 were shown on the visually obtained moment-curvature relationships. Depending on the upper deformation limit values derived, cross-sectional deformation damage levels were determined and evaluated using the moment-curvature relationships. The variation of the non-linear behavior of column models by design parameters and deformation-based damage limits were examined both analytically and visually. The deformation limits remain in a safer direction as a result of increasing longitudinal and spiral reinforcement ratios for the reinforced concrete circular columns.

Seismic Performance of R. C. Elevated Water Storage Tanks

The primary basis for construction of structures for strong ground shaking is that it shall not collapse. However, permissible damage for structural components is permitted. If a structure is permitted to be damaged in the case of severe ground shaking, it shall be constructed for seismic forces considerably lesser than those expected in the event of severe shaking if it is to remain linearly elastic. Response reduction factor, R is the factor that should be used to lower the actual base shear in order to obtain the required design lateral force. In the case of seismic design of water tanks, different values of the “R” factor are suggested by various countries, such as IBC-2000 gives the value of the “R” factor varying from 2 to 4, whereas ACI 350.3 has given the values from 2 to 4.5, whereas AWWA (D-100) recommended the values in between 3 and 4. According to Eurocode 8, the behaviour factor, also known as the “R” factor, varies between 1 and 5. The values in the Indian code for seismic analysis, IS1893-(Part 2), range from 2 to 4.Hence, it is tempting to look into the real aspect of the ‘R’ factor evaluation. IS 1893, an Indian seismic code, calculates a design shear force for an elastic structure and divides it by twice R. In other words, the term “R” refers the amount of over-strength and ductility that a structure is predicted to possess. Thus, by considering the elements, over strength factor, redundancy factor, and ductility factor, the structure can be constructed for much lesser force than is predicted by the violent shaking, preventing the structure from collapsing. Available literature shows a sound recommendation does not exist for the values of “R” given in the seismic design codes of various countries, including India. There is currently no basis for the R-values in the codes. According to the available literature, limited research has been done on the influence of viscous dampers on “R,” which reflects a structure's ability of dissipation of energy through inelastic behaviour. The finite element (FE) approach must be used in conjunction with the study of material properties, the study of nonlinear hinge properties, the investigation of the seismic response of water tanks for different water heights, and the effect of including braces in staging to reduce the seismic response of the water tank to examine the nonlinear response of tanks under dynamic time-history and push-over analysis.

Effect of Plastic Hinge Properties in Pushover Analysis of Reinforced Concrete Plane Frames

The four-bay, five-story Reinforced Concrete (RC) frame with two-dimensional beams and a column moment frame system that is vulnerable to Mosul, Iraq's seismic activity is examined. A plastic hinge symbolizes the member yielding failure mode in columns and beams. Utilizing SAP2000 software (V.16), the pushover study was carried out to confirm the code's fundamental goal of life safety performance under seismic events. By combining the seismic hazard with the inelastic structural analysis, one may determine the anticipated seismic performance of a structure. An essential outcome of pushover analysis for both brittle (force-controlled) and ductile (deformationcontrolled) actions of the plastic hinge behavior is the base shear vs structure's tip displacement curve. The pushover analysis, using a variety of alternatives for the plastic hinge behavior, showed that the plastic hinge formed because of its brittle nature placed it in the more severe category. All of the plastic hinges created in the beams as a result of brittle behavior are placed in the risky branch ("Collapse Prevention CP") of the plastic hinge acceptance criterion. This necessitates increasing the shear strength of the beams.

Comparative vulnerability analysis of structure with sand and soft soil

World frequently faces the seismic activities at different locations with varying intensities causing heavy damage to the property. Here we are doing Comparative vulnerability study between two soil type which is sand and soft soil. We will analyze two building having same dimensions, beam column sections. This paper represents the comparative vulnerability analysis which have been resulted using pushover analysis. Also the plastic hinge properties have been utilized for calculating the seismic vulnerability index to examine the performance stages of the selected building, complete used software is SAP 2000.

Development and Verification of the Capacity Curve for Two Dimensional Reinforced Concrete Moment-Resisting Frames System under Earthquake Loading

Pushover analysis is an efficient method for the seismic evaluation of buildings under severe earthquakes. This paper aims to develop and verify the pushover analysis methodology for reinforced concrete frames. This technique depends on a nonlinear representation of the structure by using SAP2000 software. The properties of plastic hinges will be defined by generating the moment-curvature analysis for all the frame sections (beams and columns). The verification of the technique above was compared with the previous study for two-dimensional frames (4-and 7-story frames). The former study leaned on automatic identification of positive and negative moments, where the concrete sections and steel reinforcement quantities the source of these moments. The comparison of the results between the two methodologies was carried out in terms of capacity curves. The results of the conducted comparison highlighted essential points. It was included the potential differences between default and user-defined hinge properties in modeling. The effect of the plastic hinge length and the transverse of shear reinforcement on the capacity curves was also observed. Accordingly, it can be considered that the current methodology in this paper more logistic in the representation of two and three-dimensional structures.

Programmable origami-inspired cellular architected building blocks for flow-regulating adaptive weir

Unprecedented properties and advanced functionalities enabled by origami-based architected materials has been demonstrated at various length scales, but most prototypes only showed single mode deformation and required external fields to trigger the reconfiguration. Here, we demonstrate a simple yet robust design strategy to program modular origami-inspired cells to achieve multi-phase adaptive behavior under flow. Guided by physical tests and numerical simulations, we qualitatively proved that our small-scale origami-inspired weirs are able to show a diverse adaptive behavior under hydrodynamic force without human input. With a specific flow-regulating target, the adaptive behavior of the proposed cellular structure can be tailored by varying the geometry and density of a baseline cell, spatial layout among cells, hinge properties and arrangements, and different boundary conditions. Governed primarily by the geometric design, the proven adaptability could be achieved at various length scales and could be integrated into diverse reconfigurable systems and devices for flow regulation and management.

Effect of Anchor Bars on Seismic Behavior of Infilled Walled Frames

User-defined plastic hinge properties obtained experimentally are used to examine the structural behavior of bare, infilled walled frames with and without anchor bars in reinforced concrete (RC) buildings. Experimentally obtained moment-curvature relationships of structural members (i.e., beams and columns) are used to determine the plastic hinge properties of each section. Three building frames are modeled and examined for time-history analysis using 20 ground-motion records. Seismic performance levels of three buildings are analyzed to determine the effects of anchor bars. Limit states at each performance level are defined, and the multi-record incremental dynamic analysis curves are obtained; 16%, 50%, and 84% fractal curves are obtained for each case. Cumulative distribution functions are constructed to summarize the varieties in the roof-drift ratios of three RC buildings with different frame types for design-based and maximum-considered earthquake hazards. It is found that, with an increased spectral acceleration of ground motions, the probability of exceeding the performance levels of infilled walled frames in reinforced buildings is reduced with the help of anchor bars. The increased stiffness of RC buildings with infilled wall frames exhibiting lower ductility is re-gained by the absorption energy of the anchor bars.

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.

Seismic performance of strengthened reinforced concrete columns

Post-earthquake reconnaissance studies have reported severe damage to reinforced concrete buildings. In a moment resistant framed building, columns are the critical members of the load path. Shear failure of a column is brittle, leading to quick degradation of the lateral strength and vertical load carrying capacity. The reported study focuses on seismic strengthening of a short shear-critical column by concrete jacketing technique. For a shear-critical jacketed column, the integrity of the new and old concrete depends on any slippage at their interface. The investigation on the effects of three different interfaces such as surface roughening, providing dowel bars or bent shear connector bars in addition to surface roughening, on the seismic performance of jacketed columns, is presented in this paper.Large-scale column specimens were tested to shear failure under lateral monotonic and cyclic loads, in presence of estimated service level axial loads. The details of the experiments and the comparison of their results in terms of shear strength, stiffness and behavior are included. The specimens with different interfaces were found to be similar in their lateral load resistance, showing negligible difference in strength. However, the specimens with bent bars showed higher stiffness compared to the specimens with other two types of interfaces. The strengths of the specimens were predicted using codal provisions and a strut-and-tie model. Their behavior was traced using a piecewise linear model. The predictions were compared with the test results. The proposed method of analysis for shear deformation can be used in developing non-linear shear hinge properties for short jacketed columns, in a pushover analysis of a building.

Effect of Hinge Properties on Nonlinear Analysis of Eccentrically Steel Braced Frames

Eccentrically Braced Frame (EBF) is one of seismic resistance of steel structures. Dissipation of seismic energies is designed by allowing plastic hinges to form in link element. Design of link elements allow plastic hinge to form due to shear or flexural failure. Structural analysis using finite element software require shear plastic hinges to be modelled. It is found that hinge properties proposed by two references, FEMA 356 and Richards & Uang are different. Study of effect of hinge properties on non-linier analysis of EBF was performed. The research is limited to hinge properties of shear link of EBFs. Numerical study was conducted on one and three storey of EBFs in two and three dimensional geometric of EBFs. Two different hinge properties from FEMA 356 and Richard-Uang were compared each other. Results show that hinge properties affect the structural response. It is found that EBFs modelled by hinge properties according to Richards-Uang has close result to experimental result than modelled built by FEMA 356. The difference between FEMA 356 and Richard-Uang to experiment are 34,54% and 15,55%, respectively.

Evaluation of performance-based earthquake engineering in Yemen

Building codes follow a common concept in designing buildings to achieve an acceptable seismic performance. The objective underlying the concept is to ensure that the buildings should be able to resist minor earthquake without damage, resist moderate earthquake with some non-structural damage, and resist major earthquakes without collapse, but some structural as well as non-structural damage. This study aims to evaluate the performance-based seismic to come up with necessary recommendations for both future practices, essential review, and restoration of existing structures in Yemen. To do this real case studies incorporated, and nonlinear pushover analysis is carried out. The analysis results presented and then assessed to find out the conformity with the required performance. The structural sections assumed at the beginning of the design, then the design repeated many times to achieve the selected performance criteria (the plastic hinge properties and the maximum displacement).

EVALUATION OF SEISMIC PERFORMANCE OF 9 STORY PRECAST BUILDINGS

Earthquakes are natural disasters that cause a significant loss of life and property. Chiang Mai is located in the north, with many earthquake faults indicating that Chiang Mai is at risk of an earthquake. This study demonstrates the importance of seismic performance base design of precast concrete buildings (PC). The 10-story apartment precast concrete building be modeled locate in Chiang Mai. The building is designed as per Department of Public Works and Town & Country Planning DPT1302-18. Buildings will be evaluated for earthquake resistance performance using nonlinear time history analysis, which uses the acceleration of the earthquake recorded from earthquakes of 7 waves. The acceleration of the earthquake will be matched to the design spectrum using ETABS software. Identify the plastic hinge properties of shear walls and moment curvature by using the stress strain model for concrete and steel as specified in Department of Public Works and Town & Country Planning DPT.1303-14. The results of analysis by the linear static analysis be designed and evaluated by the nonlinear static analysis and the nonlinear dynamic analysis. Including the analysis results from all 3 methods to compare the displacement of buildings, Base shear and Story drift.

Seismic Fragility Curves of R.C.Framed Buildings Designed as per is Low, Medium and High Code

In India, the RC buildings codes of gravity and seismic loads have been revised over five decades. The adaptation of gravity and seismic loads combination were rarely taken into design consideration in low and mid-rise building. In the last five decades, low and mid-rise buildings have been constructed high in number in urban cities due to increasing more employment opportunity. The around 56% of the landmass is prone to moderate to severe the earthquake. Also, it evident, in Bhuj 2001 earthquake, many mid and low rise was suffered severely, and more life loss occurred. The seismic zone map has been updated from 1968-2016 and seismic demand increased manifold. The RC buildings have been designed different design philosophy over the period of time, and the urgent need for the assess the vulnerability buildings which have been designed different design codes. In this paper, an attempt made to derive the fragility curves of three and five story RC buildings with aspect ratio and designed as per IS 456-1964 (Low code), IS 456-1978 (Medium code) and IS-13920 (High code). The modelling and pushover analysis are carried out by using a numerical method. User-defined hinge properties for the column as P-M-M and beam as M3 curves have been derived and assigned column and beam elements. The displacement control is applied in pushover analysis. The fragility curves have been derived as per guidelines are given by HAZUS technical manual. Results are compared with design philosophies, aspect ratio and the number of storeys for a given intensity of the acceleration.

Performance-based seismic assessment of a base-isolated bridge-pier

In structural assessments, plastic strains beyond the elastic limits play an important role in the inelastic responses under seismic effects. In this article, an isolated concrete-pier is analysed by using performance principles and the related code recommendations. Seismic performance analyses are realised by employing recorded earthquakes using the nonlinear pushover and the time history methods. The nonlinear analyses are implemented with user-defined plastic hinges. The hinge properties are derived on the basis of moment-curvature analysis and experimental results. Results of the solutions are presented comparatively for various parameters of the problem, such as pier reinforcement ratios, peak ground accelerations (PGAs) and different quakes. The results showed that residual plastic rotations of the pier section, configured with the minimum reinforcement ratio which satisfying the code-requirements, remain within the acceptable limits and they fulfil the FEMA-356 performance requirements even for strong earthquakes provided that a high ductility and proper design secured. Vulnerable functions with PGAs are displayed for the plastic rotations and isolator/deck displacements. However, the shear deformations of the isolator and the deck displacements exceed the allowable limits and they are in vulnerable risk if the pier section is configured by the minimum code-requirements.

Numerical analysis of progressive collapse for reinforced concrete frames

This research investigates numerically the potential failure of different framed structures after removal of a corner column. This study is directed towards the role of the joint above the removed column in terms of framed structures stability and internal forces redistribution utilizing linear static, nonlinear static and nonlinear dynamic analysis procedures. First, the preliminary linear static analysis as a part of more detailed nonlinear static and dynamic analysis to model reinforced concrete frames is performed. For nonlinear numerical models, three different moment-rotation capacity curves are considered for the joint above the removed column. These curves are taken according to FEMA 356 regulation according to the reinforcement condition at the joint location to represent normal joint, anchorage deficient joint and shear deficient joint. In linear static models, the results confirmed that, the more moment the joint can resist at the removed column location, the less moment is generated at the beam’s other end. In nonlinear static analysis, the model with normal plastic hinge properties recorded a higher carrying capacity than the model with both shear and anchorage plastic hinges. Nonlinear dynamic analysis with less assumptions offer the more representative modeling for the considered case study which is obvious from its closer perdition of internal forces and deflection compared to the reference findings.