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The in-plane elastoplastic failure mechanism of plate-tube-connected steel circular arches with inverted triangular cross sections is investigated in this study by using theoretical derivation and numerical simulation. First, the in-plane elastic buckling load formula of the arch under full-span uniform radial load (FSURL) is presented. Then, the limited conditions of avoiding the connecting plate and chord local failure before global elastic instability are derived. Lastly, the elastic–plastic failure mechanisms of arches are studied under FSURL, full-span uniform vertical load (FSUVL), and half-span uniform vertical load (HSUVL). It is found that the arch will experience global failure, chord local failure, combined connecting plate and chord failure, and connecting plate local failure under FSUVL and HSUVL. The failure mode is mainly related to the stiffness of the connecting plate. The corresponding design formulas are proposed for the global failure of arches and local failure of the chord. The proposed formulas and FE results are in good agreement.

The results of a numerical and experimental study of the bearing capacity of a circular concrete arch loaded with hydrostatic pressure are presented. To implement the specified scheme of loading arches, the authors made a stand that allows you to determine the bearing capacity of models of concrete, reinforced concrete, steel-fiber concrete and wooden arches. For experiments, a double-hinged arch was made of concrete С16/20. At the same time, samples-cubes with an edge size of 10 cm were prepared from the same batch, which were tested for compression in accordance with the current regulatory documents. During the tests, the load was applied in small steps for a detailed study of the arch deformation process. At each stage, the readings of the measuring devices, dial indicators and strain gauges, were recorded. For computer modeling and numerical analysis by the finite element method, the software LIRA-SAPR was used. It is noted that, despite the widespread use of arched structures made of reinforced concrete, there are still no generalizing conclusions and recommendations for determining their actual bearing capacity and strengthening methods in the domestic literature. During the tests, a breaking load of 600 kN was achieved, that is, the bearing capacity of the arch, determined experimentally, was 0.845 of the value obtained by numerical analysis, although, as a rule, in our experimental studies of other structures, the theoretical value of the bearing capacity turned out to be lower than the actual one. In this case, the destruction occurred in the support part, i.e. at the junction of the support (heel) and the arch, which is explained by the lack of reinforcement of the heel. The results of experimental and numerical studies of a concrete arch indicate that under this loading scheme, almost equal stresses arise in all cross sections of the arch. Obviously, the bearing capacity of the structure can be increased due to the uniform dispersed reinforcement of the arch and reinforcement of the heel with bar reinforcement, which determines the direction of our further research.

This study investigates the failure mechanisms and strength of plate-tube-connected circular steel arches. The upper and lower chord of the arch are joined by a series of uniformly distributed stee...

The article discussesthe research of the traditional circular archs of timber jambs, designedin the 16-th century by the French architectPhilibert Delorme, with an option of its strengthening, which make this arch comparable to the glued timber one. The experimental research of a flat arch, made of small wooden bricks strung on a steel rope and prestressed from the foundationzone, was carried out in the NRU MGSU. According to the results, it was found, that the arch has a low carrying capacity and can work only on compression. However, by strengthening the arch by using a steel band along its upper face and thus moving to the truss structure, it is possible to increase significantly its carrying capacity and bring it closer to the glued timber arch. During tests, it was noted that by the character of its work this arch is close to the circular arch of timber jambs. In the LIRA-CAD PC a computer simulationwas carried out of the traditional and the strengthened by a steel band along its upper face circular arches of timber jambs, as well as the glued timber arch. The following results were obtained.During the deformation process, the deflection of the strengthened circular arch decreased by 31%, and the stresses in it decreased by 26% compared to the traditional one, and according to the carrying capacity the arch has become comparable to the glued timber one. On this basis the conclusions were obtained, that it is possible to create non-linear form constructions, inherent to the natural objects, using the strengthened circular arch.

Various kinds of defects are usually contained in the underground roadway. When the roadway is impacted by external load, the location of defects will influence the roadway with different degrees. In order to study the effect of the location of defects on crack propagation in roadway, in this paper, the stress wave produced by the bullet impacting the incident rod was used as the impact load. Meanwhile, the variations of speed, displacement and dynamic stress intensity factor (DSIF) of cracks, during crack propagation, were obtained by using the experimental system of digital laser dynamic caustics (DLDC). And the extended finite element software ABAQUS is used for numerical simulation. Based on the method of experimental-numerical simulation, the crack propagation path is verified and the impact fracture behavior of semi-circular arch roadway with different defect positions is presented. It can be concluded that when the prefabricated crack is located at the central axis of sample, the crack propagation belongs to pure mode I; when the prefabricated crack is 5mm away from the central axis, the crack propagation appears between mode I and I-II mixed mode alternately; when the prefabricated crack is at the edge of semi-circular arch roadway, the crack propagation follows I-II mixed mode

This paper describes a proposal for a Circular Arch Viaduct. The proposal was submitted for a competition for innovation launched by Rijkswaterstaat, the Dutch Directorate-General for Public Works and Water Management, under the title ‘SBIR (Small Business Innovation Research) Circular Viaducts and Bridges’. The authors of this paper are part of a consortium consisting of BESIX NL and Ney & Partners. They have currently rounded up the first phase of the competition (Figure 1).Our society has become accustomed to the permanent availability of raw materials; our economy has been running on them for decades. At the same time, the demand for mobility and reliable infrastructure continues to grow. How do we transform the construction industry to use 50% less primary raw materials in 2030 on the way to full 100% circularity in 2050? To answer this question the Circular Arch Viaduct was developed, based on three principles: (1) the reduction of raw materials, (2) the differentiation of materials in function of required strength, and (3) the reduction of waste through re-use and recycling.Figure 1. The current concept of the Circular Arch Viaduct.

The procedure of automation of calculation of the strained-deformed state of circular arches is considered in the calculation of bending and tensile-compression deformations concentrated and distributed external loads. The aim of the work is to apply the possibilities of the boundary element method (BEM) to solve quite labor-intensive tasks of the strained-deformed state of circular arches and arch structures. To achieve the goal, a static calculation of the tensely-deformed state of circular arches in the MATLAB environment is performed. For this purpose, a system of differential equations of flat deformation of a circular rod is made and solved taking into account bending and stretching deformations along radial and tangential dis-placements. As a result of the calculation, it was concluded that numerous problems in the calculation of rings and ring systems can be solved by means of the boundary element method (BEM) equation in a coherently presented method, taking into account bending and ten-sile-compression deformations.

Unreinforced masonry (URM) structures represent most of the world architectural heritage, whose vulnerability has been also highlighted by damages and collapses occurred after recent seismic events. Numerous studies regarding the seismic capacity of masonry walls, arches and portals have been carried out by applying the so-called equivalent static analysis method, neglecting their dynamic behaviour. A proper evaluation of the dynamic response of masonry elements can be done analytically considering the dynamic equation of rigid bodies not resistant to the tensile stresses. Some studies are available in literature regarding the dynamic behaviour of walls and arches. In this framework, the paper aims to develop an analytical model, able to describe the dynamic behaviour of portals with circular arches, subjected to a base motion. Starting point of the analysis is the evaluation of the mechanism (local, semi-global or global) governing the activation of the motion of the structure, performed in the context of Limit Analysis. Subsequently the equation of motion of the system of rigid bodies is derived applying the Lagrange Equation. Finally a numerical application is carried out.

The circular-arch flexible structure is widely used in various fields, especially the support structure of the optical mirrors. This paper aims to present a generalized formulation of the circular-arch flexible structure and a continuous method to optimize this flexible structure considering the material selection and geometry simultaneously. First, an analytical model based on the variational principle is derived for calculating the radial and tangential stiffness of the flexible element, and then the generalized formulation of the integral flexible structure is obtained by considering force equilibrium and compatible deformation. Second, the structural optimization is implemented by combining the material selection and geometrical parameters, where the continuous artificial variables are used to represent the selected material. Finally, the experimental and numerical examples are given to verify the analytical formulation and the optimization scheme. The experimental and FE simulation results of the flexible element and the integral flexible structure indicate that the presented mechanical model is capable of capturing the linear behavior. For the geometrical nonlinear deformation, there exist some errors. And the optimization results demonstrate that the presented scheme is able to obtain the discrete material design and the optimal geometry.

International audience; This paper presents analytical buckling and vibration solutions for two nonlocal circular arch models. One model is based on Eringen's stress gradient theory while the other model is based on continualization of a lattice system. Both nonlocal arch models contain the unknown small length scale coefficient e(0). In order to calibrate e(0), exact buckling and vibration solutions for Hencky bar-chain model (HBM) are first obtained. On the basis of the phenomenological similarities between the HBM and the nonlocal arch models, the matching of buckling and vibration solutions for HBMs and those for nonlocal models allows one to calibrate the e(0) values. It is found that e(0) for Eringen's nonlocal circular arch (ENCA) varies with respect to geometrical property of the arch and boundary conditions. However, e(0) for a continualized nonlocal circular arch (CNCA) is found to be a constant value, regardless of geometrical properties or boundary conditions. (C) 2017 Elsevier Ltd. All rights reserved.

Aim of the paper is the study of the rocking of the masonry arch that, hit by a horizontal impulse of acceleration, moves sideways according to a mechanism u− defined by four hinges. The arch, once reached a maximum side displacement, inverts its motion going back, still moving along the same mechanism. At a time instant t, it reaches the zero configuration and it cannot continue its motion along u− because all the hinges of this mechanism are now blocked. A reverse mechanism thus takes place. The arch mobilizes the new mechanism u+ that has the “mirror” positions of the hinges of the mechanism u−. A new impact model, alternative to the ones available in literature and pointing out all the questionable problems, is proposed in this paper. It is thus shown that impacts occur in the points where are located the hinges of this new mechanism u+: energy losses take place at these impact points.

Continuously transposed cable (CTC) is a multistranded conductor mainly for application in power transformers. As its structure is complicated a simplified simulation model and an easy analytic model for the buckling analysis of transformer coils are investigated in this paper. In the simplified models the transposition of the strands is neglected leading to an easy rotation symmetric cross section. These simplified models are compared to detailed models using finite element analysis (FEA) based linear and nonlinear buckling simulations. Furthermore analytical approaches are adopted from the buckling-behavior of a circular arch for the use with CTCs. All models are compared with respect to their critical buckling load for some typical winding and CTC dimensions varying between 11 to 41 strands. The maximum deviation between detailed and simplified FEA based CTC models for both linear and nonlinear buckling analysis lies below 13%. The deviations for the analytic approaches are with a maximum of 22% higher but serve to verify the trends deduced from the simulation results.

The fundamental role of geometry on the stability of historical arched structures has been unveiled centuries ago. In this study, a segmental arch consisting of an elliptical upper part (extrados) and a circular lower part (intrados) is introduced. This so-called part-elliptical arch is treated as a rigid monolithic body enabled to rock on a triggering base. The objective of the study is to extend the established methods applicable to the conventional circular arches, particularly in terms of: (i) stability analysis at incipient uplift, (ii) time-history analysis of the rocking response. The results are presented comparatively to those extracted from the circular arch of the same geometric characteristics.

In-plane free vibration of functionally graded graphene platelets reinforced nanocomposites (FG-GPLRCs) circular arches is investigated by using the two-dimensional theory of elasticity. The graphene platelets (GPLs) are dispersed along the thickness direction non-uniformly, and the material properties of the nanocomposites are evaluated by the modified Halpin-Tsai multi-scaled model and the rule of mixtures. A state-space method combined with differential quadrature technique is employed to derive the governing equation for in-plane free vibration of FG-GPLRCs circular arch, the semi-analytical solutions are obtained for various end conditions. An exact solution of FG-GPLRCs circular arch with simply-supported ends is also presented as a benchmark to valid the present numerical method. Numerical examples are performed to study the effects of GPL distribution patterns, weight fraction and dimensions, geometric parameters and boundary conditions of the circular arch on the natural frequency in details.

Lateral buckling of cantilevered circular arches under various end moments is studied using an analytical approach. Three types of conservative moments are considered, i.e. the quasi-tangential moments of the 1st and 2nd kinds, and the semi-tangential moment. The induced moments associated with each of the moment mechanisms undergoing three-dimensional rotations are included in the Newman boundary conditions. Using the differential equations available for the out-of-plane buckling of curved beams, the analytical solutions are derived for a cantilevered circular arch, which can be used as the benchmarks for calibration of other methods of analysis.

The buckling behavior of functionally graded graphene platelet-reinforced composite (FG-GPLRC) shallow arches with elastic rotational constraints under uniform radial load is investigated in this paper. The nonlinear equilibrium equation of the FG-GPLRC shallow arch with elastic rotational constraints under uniform radial load is established using the Halpin-Tsai micromechanics model and the principle of virtual work, from which the critical buckling load of FG-GPLRC shallow arches with elastic rotational constraints can be obtained. This paper gives special attention to the effect of the GPL distribution pattern, weight fraction, geometric parameters, and the constraint stiffness on the buckling load. The numerical results show that all of the FG-GPLRC shallow arches with elastic rotational constraints have a higher buckling load-carrying capacity compared to the pure epoxy arch, and arches of the distribution pattern X have the highest buckling load among four distribution patterns. When the GPL weight fraction is constant, the thinner and larger GPL can provide the better reinforcing effect to the FG-GPLRC shallow arch. However, when the value of the aspect ratio is greater than 4, the flakiness ratio is greater than 103, and the effect of GPL’s dimensions on the buckling load of the FG-GPLRC shallow arch is less significant. In addition, the buckling model of FG-GPLRC shallow arch with elastic rotational constraints is changed as the GPL distribution patterns or the constraint stiffness changes. It is expected that the method and the results that are presented in this paper will be useful as a reference for the stability design of this type of arch in the future.

This paper investigates the nonlinear elastic in-plane dynamic buckling of a fixed shallow circular arch that was subjected to an arbitrarily located step radial point load, which has not b...

We provide a comprehensive stability analysis of the thermoelastic Bresse system (also known as the circular arch problem). In particular, assuming a temperature evolution of Gurtin–Pipkin type, we establish a necessary and sufficient condition for exponential stability in terms of the structural parameters of the problem. As a byproduct, a complete characterization of the longtime behavior of Bresse-type systems with Fourier, Maxwell–Cattaneo and Coleman–Gurtin thermal laws is obtained. Our main theorem also subsumes some recent achievements in the stability properties of thermoelastic Timoshenko systems with classical and nonclassical heat conduction.

Effects of different load modes, rise-span ratios and support conditions on out-of-plane buckling and differences between parabolic and circular arches were studied. With the increase of rise-span ratio, buckling loads of arches under vertical load uniformly distributed along the horizontal line get bigger and bigger compared with those of vertical load uniformly distributed along the axis. With increase of rise-span ratio, the buckling loads of hingeless and two-hinged arch increase after decrease, then decrease. The buckling load of three-hinged arch decreases after increases. When rise-span ratio is small, support condition has a great influence on out-of-plane buckling. The parabolic arch is better than circular arch in out-of-plane stability and economy. But circular arch is better than parabolic arch in manufacture.

In recent years, floods and earthquakes occur frequently and cause great threats and harm to personal safety. On the basis of my patent named anti-seismic bed, which patent id is 200920287683.8, the flood control and anti-seismic bed is proposed. The anti-seismic bed doesn’t need external power supply and storage battery. When an earthquake occurs, the protection device starts and then an circular arch are formed by rotating protection boards. people are protected in bed body in 0.765s. When floods occur, flood protection airbag is filled with gas and launched by the Atmel89C52 microprocessor and YDE-WDT-P sensors. Bed body can float in the flood. Its functions are similar to the rescue boat and can protect human life’s safety.

The stability of roadway surrounding rock plays an important role in the safety of roadway, so the classification of roadway stability becomes an indispensable part in the safety analysis of coal roadway. Based on the statistical analysis of 25 relevant literatures and the principle of index selection, 12 classification indexes were determined by comprehensive analysis. A genetic neural network model was established. Data of 12 straight wall semi-circular arch roadways were investigated as training samples, and 4 roadways were selected for testing. The prediction accuracy of the model is 100%. Combining with the theory of strong support for coal roadway sidewall and angle, the stability classification model is applied to the classification of surrounding rock stability of straight wall semi-circular arch roadway, and reasonable supporting countermeasures and suggestions for different grades of surrounding rock are given. In order to verify the reliability of the model, the model has been applied in engineering, and achieved good results. It proves that the model has goodfit and strong applicability.

Finite element model which can reflect the effects of different loading positions were constructed with Beam 188. Effects of different restraints, load models and rise-span ratios on out-of-plane buckling were studied by comparing results of fixed arches with that of pin-end arches under three loading models. It is conservative to design by employing results of radial loading. For ideal restraints, out-of-plane stability of pin-end arches is better than fixed arches when rise-span ratio is big. Effects of different loading positions on out-of-plane buckling were studied. Buckling loads of arches which are loaded at arch-axises are bigger than those of top flanges, but smaller than those of bottom flanges.

Paper describes a bearing structure shaped as a cylindrical shell, designed from cold-formed 1 mm thick steel sheets, according to so called ABM system. The transversal shaping (folding) and longitudinal forming (a circular arch) of ABM profile is executed in situ. The structure is offered for halls with spans reaching even 25 m. The work presents analysis of safety of two such objects whose execution was stopped and two other in Gdansk (Poland) and Tuszyn (Poland) that have collapsed.

By the setting torsional and lateral displacement function of sidewise buckling of two-hinged circular arch under concentrated force, the single-arch structure's bending, torsional deformation and external force potential can be constructed. An analytical solution for the lateral critical buckling load of two-hinged arch is first deduced by using the energy method; the results are also compared and analyzed by the finite element method. The results show that the analytical solution of single arch’s lateral critical buckling load is in good agreement with the finite element numerical solution, and the validity of the formula is proven.

Generalised functions have been widely adopted in structural mechanics to treat singularities of beam-like structures. However due to the curved geometry, that couples axial and transversal displacements, their use has never been explored for curved beams. In this paper the capability of distributions of leading to closed form exact solutions for multi-cracked circular arch is shown. The exact closed-form solution of a circular Euler arch in presence of any number of discontinuities due to concentrated damage and subjected to an arbitrary distribution of static loads is obtained. Damage, under the form of concentrated cracks, has been modeled through the widely adopted and validated equivalent elastic hinge concept and has been introduced in the governing differential equations by making use of Dirac's delta functions. The resulting nontrivial generalised six order differential equations have been derived and solved in closed form. Independently of the number of along arch concentrated cracks, the solution is expressed as a function of six integration constants only in which the damage positions and intensities are given data appearing explicitly in the solution expression. This latter aspect constitutes a fundamental aid towards the resolution of the static damage inverse identification problem. The results have been validated through some comparisons with finite element numerical simulations: examples referred to multi-cracked Euler arches with different boundary conditions, damage and load scenarios are presented.

The equilibrium equations of elastic support circular arches considering geometrical imperfections are deduced from variation principle. And the relations between external load, radial displacement and axial forces are determined; also the equilibrium conditions of snap-through buckling and bifurcation buckling in circular arch are ascertained respectively. Further, influences of geometrical imperfections and elastic supports on in-plane stability are analysis with analytical and finite element (FE) method. And the compared results display that the two methods coincide with each other very well for smaller opening angle in circular arches. The geometrical imperfections have only certain effects on the buckling path, while the elastic support rigidity play a significant role in both the path and critical load of snap-through buckling.

Results of analyses of the profile shaping of a corrugated pipe are presented. Cases of the shaping of a low-profile corrugation, and the shaping of a high-profile corrugation with vertical and inclined walls and a plane and circular arch are examined.

Ideally, structural health monitoring of civil infrastructure consists of determining, by measured parameters, the location and severity of damage in the structure. Many structural vibration parameters have been used to identify and quantify damage. Using parameters based on structural vibration phase space features for damage detection is a new field in structural health monitoring. In this article, a new parameter based on topology changes of the phase space of vibration signals is proposed to identify structural damage, and an index named changes of phase space topology derived from vibration time history is used to locate the damage. A circular arch structure is used to demonstrate the method. Both numerical simulation and experimental tests of dynamic responses of a scaled arch structure to impact loads are carried out. The obtained structural response data are used to detect structural damage. Both the experimental and numerical results indicate that this method can successfully locate damage. It also demonstrated that this proposed method is more sensitive to damage but less sensitive to noise than modal-based parameters. The proposed damage index can be a good candidate in an online structural health monitoring system, as it depends on global vibration measurements but is more sensitive to structural damage than other global vibration-based parameters such as vibration frequencies and mode shapes.

Non‐linear analyses of the preforming process of a multilateral junction assembly are reported in this paper and plasticity and geometric non‐linearity including large deformation have been accounted for. A circular arch with both longitudinal sections being built‐in and compressed laterally by a rigid elliptic hold‐down plate is studied first. A rigid–perfectly plastic model is adopted and a collapse mode is proposed. By analysing the relationships between loading and deformation under each collapse mode, the incipient collapse load and force–deflection curve for the circular arch are presented. The relation between compressing force and deformation during preforming process of multilateral junction assembly is then obtained by integrating along the multilateral leg longitudinally. The research will provide guidance for structural design of multilateral tools and for application of multilateral well technology.

Arch bridge as well as arch frame of building is òne kind of plane-curved-bar system of bearing pressure.When the load of arch carrying reaches some value, the arch will lost the balance stability. Based on the theory of precise transfer matrix method and differential equation of circular arch in plane, a new method for plane-buckling analysis of circular arch under uniform load is derived, by which the critical load of circular arch with two hinge supports is calculated. Compared with the theoretical solution, they anastomosed each other well, that shows the method is right and effective.

Conventionally, when a circular arch is subjected to uniform radial loading, the difficulty in performing an accurate prebuckling analysis is usually circumvented by considering that the uniform radial loading produces axial compression, but no bending, in the arch. However, the transverse loading may produce bending as well as axial compression in the arch, particularly in shallow arches, and the arch may deform considerably prior to buckling. Treating the prebuckling stresses in the arch as being trivial is therefore questionable, and the prebuckling analysis should be carried out with caution. This paper investigates the prebuckling response of the classical analysis and its effects on determining the out-of-plane and in-plane elastic buckling loads of circular arches that are subjected to uniform radial loading. It is found that the current solutions based on the classical prebuckling analysis overestimate the in-plane buckling loads of shallow arches and underestimate the out-of-plane buckling loads of shallow arches significantly. Proper prebuckling analyses for out-of-plane and in-plane buckling are presented and new analytical solutions for the out-of-plane and in-plane buckling loads of arches are derived accounting for both axial compressive and bending actions.

We find families of finite deformations of a Cosserat elastic continuum on which the system of equilibrium equations is reduced to a system of ordinary differential equations. These families can be used to describe the expansion, tension, and torsion of a hollow circular cylinder, cylindrical bending of a rectangular slab, straightening of a circular arch, reversing of a cylindrical tube, formation of screw and wedge dislocations in a hollow cylinder, and other types of deformations. In the case of a physically nonlinear material model, the above-listed families of deformations can be used to construct exact solutions of several problems of strong bending of micropolar bodies.

The masonry pointed arch, largely used in Gothic architecture, is known to have lower horizontal thrust than the circular arch. While this fact is widely acknowledged, the structural behavior of the pointed arch has not been researched in sufficient detail. This article compares the circular and the pointed arch, evaluating the maximum and minimum thrusts, analyzing the collapse due to support displacement and assessing the maximum capacity for concentrated loads for a range of arch geometries. Graphical and numerical analyses were performed in order to predict failure as the supports are displaced. An extensive experimental campaign on model arches has been carried out and compared to the theoretical results. The article provides new conclusions about the behavior of the pointed arch and the conditions necessary for collapse to occur.

In this paper, the formulation of the curved beam element by trigonometric functions for the curvature, which is an alternative to the displacement function is presented. Trigonometric function is chosen for the curvature to avoid the shear and membrane locking phenomena. In the developed formulation, the force—curvature relationships in polar coordinate system have been obtained first; then the curvature of the element has been assumed to have a trigonometric function form; and the radial and tangential displacements, and rotation of the cross-section have been found to be a function of the curvature. Moreover, the relationship between the nodal curvatures and the nodal deformations has been calculated and used for determining the deformations in terms of curvature at an arbitrary point. The total potential energy has been calculated accounting for bending, shear, and tangential deformations. Invoking the stationary condition of the system, the force—deformation relationship for the element has been obtained. Using this relationship, the stiffness matrix and the equivalent fixed loads applying at the nodes have been computed. In such an equilibrium equation, the locking phenomenon is eliminated. The formulation is applied to six examples to verify its capabilities. The results demonstrate that the presented element is capable of representing the behaviour of the curved beam with adequate accuracy and efficiency as compared with the previous methods.

This paper presents the experimental results of the dynamic behaviour of a circular arch in undamaged and several damaged configurations, and compares them with those obtained by means of analytical methods. The damage is introduced in the undamaged arch by operating a notch and is then modelled as a torsion spring of suitable stiffness localised in the damaged cross-section. Good agreement between analytical and experimental results is observed. An identification procedure based on frequency measurements is proposed and validated.

In this paper, a finite element technique was used to determine the natural frequencies, and the mode shapes of a circular arch element was based on the curvature, which can fully represent the bending energy and by the equilibrium equations, the shear and axial strain energy were incorporated into the formulation. The treatment of general boundary conditions dose need a consideration when the element is incorporated by the curvature-based formula. This can be obtained by the introduction of a transformation matrix between nodal curvatures and nodal displacements. The equation of the motion for the element was obtained by the Lagrangian equation. Four examples are presented in order to verify the element formulation and its analytical capability.

An innovative displacement-dependent metallic yielding damper designed to deform inelastically under in-plane flexural bending for seismic protection of building structures is proposed. The in-plane flexural damper that originated from a portal frame is modified by replacing the beam with a circular arch so that the effect of stress concentration can be minimized. Component tests of the in-plane dampers were conducted and compared with analytical results. Hysteresis of the component test indicates a consistent energy-dissipative characteristic of the damper. Moreover, seismic performance of the proposed damper via a series of shaking table tests was carried out. Excellent seismic performance of the proposed in-plane arched damper was observed. The acceleration responses in both peak and root-mean-squares of all floors are significantly reduced, and were greater in extent compared to the earthquake intensity increases.

This paper investigates the free in-plane vibration of stepped circular arches. The effects of axial extension, transverse shear deformation and rotatory inertia are included in the governing equations. The solution is obtained exactly by using the initial value method. The solution procedure is also applied to cases in which only one effect is considered in order to determine its contribution to the results. The results show that the aforementioned effects must be taken into account to get a better approximation to the actual behaviour of an arch, even if it is slender. The effects of step ratio, location of the step, boundary condition, opening angle and slenderness ratio on the frequency coefficients are studied. The mode transition phenomenon is also investigated and the mode shapes are given in figures. The examples in the literature are solved and comparisons are presented in the tables. Numerical solutions are obtained by using ANSYS which is a commercial finite element program. Experiments are also performed to verify the theoretical and numerical results.

This paper develops a closed-form solution for the elastic flexural–torsional buckling of a laterally fixed steel circular arch that is subjected to uniform bending. The formulation makes recourse to an orthogonal rotations matrix in order to derive the finite strains and the energy equation for buckling. Whilst the flexural–torsional buckling of pinned arches has received some degree of treatment in the literature, it appears that the flexural–torsional buckling of fixed arches has not been reported openly. The buckling solutions are very different from those of pinned arches, and significantly they illustrate that the concept of an ‘effective length’ approach, that is often useful for determining the buckling response of straight beams or columns, is not applicable for the flexural–torsional buckling of arches. The ramifications of this observation are that design procedures for the out-of-plane buckling of pinned arches cannot be used as a basis for design procedures for fixed arches.

The differential quadrature (DQ) methodology introduced by the authors [see, Comput. Methods Appl. Mech. Engng. 191 (2002a) 3509; Int. J. Solids Struct. 39 (19) (2002b) 4927; Int. J. Numer. Methods Engng. 54 (3) (2003a) 847; J. Sound Vibrat. 263 (2) (2003b) 415] is employed for out-of-plane static analysis of circular arches under a wide spectrum of boundary conditions. In addition to the classical boundary conditions, elastic restraints against translation and rotation are also considered. Different loading conditions are examined. Several examples of arches with uniform, continuous or stepped varying cross-sections are presented to demonstrate the accuracy of the methodology. The domain decomposition technique in conjunction with the present DQ methodology is examined for certain cases. The results are compared with those of exact solutions for several uniform or stepped sections arches and also for arches on elastic foundations. Accurate converged numerical solutions are obtained with only few grid points.

Bitemark analysis of humans and domestic animals is by far the most demanding and complicated part of forensic dentistry. This study compared and analyzed the bite mark impression patterns of 34 domestic animals and 16 humans. Bitemark comparison included comparing the bitemark of the suspected biter's distinctive dental features to determine whether a link exists between the two sets of evidence. Oval or elliptical arch shape of humans, circular to oval shape of dog, circular arch shape of cat was noted. The incisor morphology for humans was rectangular shape, oval to rectangular for dogs, circular for cats was observed. The inter canine distance of humans measured on dental cast ranged from 22–40 mm with a standard deviation of 5.0 and mean of 33.2, 32–50 mm with a standard deviation of 4.11 and mean of 38.44 for dogs, 11.80 to 18.24 mm with a standard deviation of 2.44 and mean of 16.14 for cats. Intercanine distance, arch shape are few, simple reliable parameter to differentiate between bite marks that are produced by humans and domestic animals. The outcome of the study serves and helps the forensic fraternity of different expertise such as forensic odontologist, forensic pathologists, veterinarians, biologists, crime investigators, and others.