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In order to achieve a consistent level of failure probability, structural design codes are optimized using probabilistic methods. This optimization process traditionally focuses on the ultimate limit states (ULS). However, in the design of timber structures the performance of the structural members is often governed by the serviceability limit state (SLS) associated with different load levels than applied in the ULS. The probability of serviceability failure is strongly dependent on the loading sequence and the time-dependent response of timber; therefore, a time-variant probabilistic model is recommended to estimate them properly. This study aims to investigate the time-dependent reliability for long-term deflections of timber office and residential floor beams according to the specifications of the Eurocodes. A simple creep model is used to calculate the deflections and Monte Carlo simulation is carried out to determine the reliability index. It was found that the creep factor and the suggested deflection limits given in Eurocode 5 might not be appropriate to achieve the expected target reliabilities. To obtain a more consistent reliability, more suitable values for the mentioned parameters were suggested. However, the primary aim was to present a framework to determine appropriate deflection limits for structural codes.

Magnetostrictive thin films primarily find use for their actuation properties. Micro-electro-mechanical systems (MEMS devices) capitalize on the induced mechanical deformations when these thin films are subjected to a magnetic field. In this study, experiments are conducted on Tb-Dy-Fe thin film samples to determine their characteristic magnetization curves. The thin films are subjected to a periodically varying magnetic field of �0.6 T and the deflections at the tip are measured. A simple analytical model based on the theories of elasticity and considering transversely isotropic material properties of both the film and the substrate layers has been proposed to predict the deflections. The study has been extended to predict the tip deflections numerically using Comsol Multiphysics. The measured tip deflections are further compared with the simulated analytical and numerical results, which are found to agree with each other. � 2015 Elsevier B.V. All rights reserved.

Tool wear on the cutting edges of micro end mills is an important issue affecting process outputs such as tool deflections and surface roughness, especially when difficult-to-cut materials such as titanium alloys, stainless steel, etc. are machined at micro scale. An understanding of the interactions between tool wear, machining forces, tool deflections, and surface roughness is important in order to maintain component quality requirements. However, in literature, the number of studies concerning tool wear in micro end mills is limited. The goal of the paper is to better understand tool wear patterns (flank wear, edge rounding) of micro end mills and their relationship to machining parameters. In this study, first, the influence of tool wear on micro milling forces and surface roughness parameters is analyzed and favorable micro milling process parameters are identified. It is shown that, when machining with worn end mills, forces are affected by the tool wear patterns. Then, the influence of increased milling forces due to tool wear on tool deflections and tool breakage is studied using both experimental techniques and finite element analysis. The finite element model-based tool deflection and tool breakage predictions are validated through experiments. The results of this study can be used in process parameter selection in pocket micro milling operations and tool condition monitoring systems.

The authors refer to the laboratory testing carried out on model caisson embedded in marine clay collected from the Chennai coast in India. The response of lateral load-ground level deflection of caissons under static and cyclic lateral loading is presented and discussed for the varied parameters such as caisson embedment depth ratio (L/D), load eccentricity ratio (e/D), and undrained strength (s u) of clay. The results showed that as the caisson L/D increases, the lateral load required to cause a specified ground level deflection increases. At a given lateral load, the deflection levels are increased as the load eccentricity ratio increases from 0.5 to 2.0. As L/D increases from 2 to 3, the increase in the ultimate lateral capacity is found to be 1.8 to 2.0 times. Similarly, for the change in L/D from 3 to 4, this increase in capacity is found to be 1.6 to 1.8 times at all the undrained strength values and e/D values tested. From the cyclic load test results, it was noticed that the deflections mobilized at the cyclic load ratio (CLR = 0.6) were so small and these are hardly 1% to 2% of the diameter of the caisson. A marked increase in the ground level deflection up to about 900 cycles was observed and thereafter the deflection almost remained the same. � 2012 Copyright Taylor and Francis Group, LLC.

The shape of a doubly clamped bridge structure depends on its deflection. At large deflections, where the system exhibits nonlinear behaviour, the shape effect becomes significant. We present a general method, based on variational analysis, for computing corrections to the nominal linear regime shape function. The method is used to compute the first non-trivial correction and quantify the corresponding improvement in the large deflection regime. The model obtained is also validated using FEM simulations.

cited By 0; International audience; The overall performance of an electrostrictive polymer is rated by characteristic numbers, such as its transverse strain, blocking force, and energy density, which are clearly limited by several parameters. Besides the geometrical impact, intrinsic material parameters, such as the permittivity coefficient as well as the Young's modulus and the breakdown electric field, have strong influences on the actuation properties of an electroactive polymer and thus on the device's overall behavior. As a result, an analysis of the figures of merit (FOMs) involving all relevant material parameters for the transverse strain, the blocking force, and the energy density was carried out, making it possible to determine the choice of polymer matrix in order to achieve a high actuator performance. Another purpose of this work was to demonstrate the possibility of accurately measuring the free deflection without the application of an external force and inversely measuring the blocking force under quasi-static displacement. The experimental results show good electrostrictive characteristics of the plasticized terpolymer under relatively low electric fields. © 2018 by the authors.

Displacement field based on higher order shear deformation theory is implemented to study the static behavior of functionally graded metal-ceramic (FGM) beams under ambient temperature. FGM beams with variation of volume fraction of metal or ceramic based on power law exponent are considered. Using the principle of stationary potential energy, the finite element form of static equilibrium equation for FGM beam is presented. Two stiffness matrices are thus derived so that one among them will reflect the influence of rotation of the normal and the other shear rotation. Numerical results on the transverse deflection, axial and shear stresses in a moderately thick FGM beam under uniform distributed load for clamped-clamped and simply supported boundary conditions are discussed in depth. The effect of power law exponent for various combination of metal-ceramic FGM beam on the deflection and stresses are also commented. The studies reveal that, depending on whether the loading is on the ceramic rich face or metal rich face of the beam, the static deflection and the static stresses in the beam do not remain the same. � 2007 Elsevier Inc. All rights reserved.

Experimental investigation was planned and conducted to study the influence of brick masonry infill in a reinforced cement concrete frame. The analytical methods available needs validation by comparison with experimental results and more accurate methods of analysis like finite element analysis has to be used for the above purpose. In this study, RC frame with middle bay brick infilled representing a five-stories, three bay building in quarter-scale has been taken for experimental investigation and the available methods of theoretical analysis and finite element analysis using ANSYS software for the frames have been carried out. Until the cracks developed in infills, the contribution of the infill to both lateral stiffness and strength was very significant. The change in lateral stiffness, strength, ductility and natural period of the framed structure due to the presence of infills change the behaviour of the building under seismic action. The object of this study was to investigate the behaviour of such infilled frames under seismic loads. For this purpose, five stories, three bay frames with central portion infilled with brick were tested under static cyclic loading simulating seismic action. Analytical works was done to understand the stiffness, strength and behaviour of these types of frames. � 2007 Asian Network for Scientific Information.

The geometric nonlinear responses of laminated composite cylindrical panels subjected to (i) axial compression and (ii) central concentrated load are investigated in this work. The parameters considered are: number of layers, symmetric/antisymmetric laminate constructions, cross-ply/angle-ply fibre orientation, boundary conditions and central angle of panel. An eight-node degenerated layered shell element with an efficient explicit through-thickness integration scheme is employed. It has been observed that the cylindrical panels under axial compression exhibit stable post-buckling paths and the number of layers in the laminate for a given total thickness has considerable influence on the load-deflection behaviour. The strength of shallow panels with longitudinal edges hinged, curved edges free and subjected to a central concentrated load is controlled by the limit point load, whereas for deep panels with other parameters remaining the same, the strength is controlled by the bifurcation load. The boundary conditions have significant influence on the load-carrying capacity. The panels with longitudinal edges hinged and curved edges free should be avoided in construction, as they undergo either limit point or bifurcation failure at very low load levels compared with other edge conditions. ? 2001 Elsevier Science Ltd.

We study single-beam deflection and asymmetry in transmission, two aspects of the same phenomenon that appear in the topologically simple, nonsymmetric, photonic crystal (PhC)-based structures without corrugations at the interfaces. Strong diffractions enabling efficient blazing, i.e., redistribution of the incident wave energy in favor of the desired higher diffraction order(s), can be achieved owing to the defect-like layer(s) embedded in a regular slab of PhC. The main features, together with the peculiarities of the two basic transmission types and relevant coupling and deflection scenarios, are discussed, for one of which a part of the PhC works in the evanescent-wave regime. Performances are suggested, in which efficient single-beam deflection and asymmetry in transmission can be obtained even when the irregular layer is deeply embedded. More than 97% of the incident wave energy can be converted into a single deflected beam that is associated with the first negative diffraction order, even though the entire structure is nonsymmetric and the diffractive element is located at some distance from the incidence interface. (C) 2016 Optical Society of America

A design methodology for two-speed gearboxes is presented in this paper. The input horse power, the input speed and net reductions in the gearbox are the parameters to be specified. The user is given the choice of shaft and gear material. The methodology specifies the shaft dimensions, gear specifications, bearing selection and overall space occupied and the self weight of the gearbox. The methodology also involves comparison of the design stresses obtained from classical design methodology with those obtained from the FEM modeling of the problem, along with the dynamic analysis of the model. The deflections of the shaft under the action of gear forces are determined using both FEM and classical methods. ? 1997 Elsevier Science Limited. All rights reserved.

An investigation to study the behaviour of reinforced concrete four-pile caps by three-dimensional nonlinear finite element analysis is presented. Four-pile caps having different reinforcement layouts were considered. Eight-noded isoparametric brick elements with incompatible modes and two-noded three-dimensional truss elements were used to model the concrete and steel, respectively, of the pile caps. The steel elements were assumed to lie on the edges of the brick elements. The smeared cracking model was employed for modelling cracks during the analysis. The nonlinear components, such as multiaxial compressive behaviour of concrete, including strain softening, cracking of concrete and yielding of steel reinforcement, were considered. The load deflection characteristics, the strains in the reinforcement, the crack patterns and the ultimate loads are presented herein. Some of the theoretical results are compared with those obtained from experiments carried out on reinforced concrete pile cap specimens. ? 1995.

A special class of fixed-wing micro-air-vehicle (MAV) is currently being designed to fly and hover to provide range superiority as well as being able to hover through a flight maneuver known as prop-hanging to accomplish a variety of surveillance missions. The hover maneuver requires roll control of the wing through differential aileron deflection but a conventional system contributes significantly to the gross weight and complexity of a MAV. Therefore, it is advantageous to use smart structure approaches with active materials to design a lightweight, robust wing for the MAV. The proposed smart wing consists of an active trailing edge flap integrated with bimorph actuators with piezoceramic fibers. Actuation is enhanced by preloading the bimorph actuators with a compressive axial load. The preload is exerted on the actuators through a passive latex or electroactive polymer (EAP) skin that wraps around the airfoil. An EAP skin would further enhance the actuation by providing an electrostatic effect of the dielectric polymer to increase the deflection. Analytical modeling as well as finite element analysis show that the proposed concept could achieve the target bi-directional deflection of 30° in typical flight conditions. Several bimorph actuators were manufactured and an experimental setup was designed to measure the static and dynamic deflections. The experimental results validated the analytical technique and finite element models, which have been further used to predict the performance of the smart wing design for a MAV. © 2011 IOP Publishing Ltd.

The aim of this paper is to analyse the stress levels in a composite centrifugal fan impeller in a steady-state condition. In the solution procedure a cyclic symmetric approach is used, coupled with a modified Potter's scheme of solving simultaneous equations. This means less computer time and memory are required. Two composite materials, namely glass-epoxy and boron-epoxy, have been studied. Radial and circumferential fibre orientations are analysed. Maximum stress levels at different speeds have been calculated. Maximum deflections and factor of safety at 2000 rpm under both fibre orientations for the above materials are obtained.

The use of metal matrix composites in railway wheel applications is explored in this paper. Static and dynamic analysis of railroad wheels made of metal matrix composites are made using the finite element method. The deflections, stresses, factor of safety and natural frequencies of these wheels are compared with those in steel as well as graphite/epoxy wheels.

The non-linear bending analysis of simply supported symmetrically laminated orthotropic plates subjected to uniformly distributed load, using an accurate displacement based higher-order theory is presented. The non-linear governing equations are solved by the Galerkin procedure with the use of the Newton-Raphson method. Numerical results given here, based on analytical investigation, will be useful for comparison in future.

This contribution presents the kinetostatic analysis of a spatial compliant mechanism actuated by three Shape Memory Alloy (SMA) wire actuators. This mechanism exploits both shape memory and superelastic effects of SMA actuators. The moving platform of the mechanism is mounted on a pillar made of superelastic SMA and its mobility is obtained from the large deflection of the pillar by the selective actuation of any one or two wires in differential manner. The deflection expressions obtained are basically force-displacement kinematic relationships, derived after incorporating follower forces and variable moments developed by the actuators. Two sets of geometric parameters, related to deflected and undeflected conditions, have been utilized to solve the coupled relationship between the force developed by the SMA actuation and the force required for the elastica deflection. The deflection expressions are solved using Romberg integration method and the numerical results obtained have been validated by comparing them with those obtained from FEM simulation. The results show that, for the design of compliant mechanisms exhibiting large displacements the force-displacement relationships in linear form, as applicable to small deflections, are no longer valid.

This paper describes a method to analyze for the large deflections of curved prismatic cantilever beams with uniform curvature subjected to a follower load at the tip. The large deflection, the deflection dependent follower load and the initial curved geometry are the important features of the beam considered in this work. Shear force formulation proposed by Lee [Large deflections of cantilever beams of non-linear elastic material under a combined loading. Int J Non-Linear Mech 2002;37(3)] is used for deriving the governing equations. Using this approach, the resulting two point boundary value problem (TPBVP) can be reduced to an initial value problem (IVP). Fourth order Runge-Kutta method along with one parameter reverse shooting method is applied to the numerical solution to the problem. A novel approach presented in this paper of integrating from the free end to the fixed end of the cantilever beam simply replaces the two parameter shooting with a single parameter shooting yielding several advantages. This solution technique is demonstrated for various types of follower tip loads on curved and straight cantilever beams and is validated with existing solutions in the literature. � 2009 Elsevier Ltd. All rights reserved.

The self-healing behavior of a series of pre-cracked fiber reinforced strain hardening cementitious composites incorporating blast furnace slag (BFS) and limestone powder (LP) with relatively high water/binder ratio is investigated in this paper, focusing on the recovery of its deflection capacity. Four-point bending tests are used to precrack the beam at 28 days. For specimens submerged in water the deflection capacity can recover about 65-105% from virgin specimens, which is significantly higher compared with specimens cured in air. Similar conclusion applies to the stiffness recovery in water cured specimens. The observations under ESEM and XEDS confirmed that the microcracks in the specimens submerged in water were healed with significant amount of calcium carbonate, very likely due to the continuous hydration of cementitious materials. The self-healing cementitious composites developed in this research can potentially reduce or even eliminate the maintenance needs of civil infrastructure, especially when repeatable high deformation capacity is desirable, e.g. bridge deck link slabs and jointless pavements. © 2009 Elsevier Ltd. All rights reserved.

The self-healing behavior of a series of pre-cracked fiber reinforced strain hardening cementitious composites incorporating blast furnace slag (BFS) and limestone powder (LP) with relatively high water/binder ratio is investigated in this paper, focusing on the recovery of its deflection capacity. Four-point bending tests are used to precrack the beam at 28 days. For specimens submerged in water the deflection capacity can recover about 65-105% from virgin specimens, which is significantly higher compared with specimens cured in air. Similar conclusion applies to the stiffness recovery in water cured specimens. The observations under ESEM and XEDS confirmed that the microcracks in the specimens submerged in water were healed with significant amount of calcium carbonate, very likely due to the continuous hydration of cementitious materials. The self-healing cementitious composites developed in this research can potentially reduce or even eliminate the maintenance needs of civil infrastructure, especially when repeatable high deformation capacity is desirable, e.g. bridge deck link slabs and jointless pavements. © 2009 Elsevier Ltd. All rights reserved.

A compliant miniature parallel manipulator made of superelastic nitinol pipe as its central pillar and actuated by three symmetrically attached shape memory alloy (SMA) wires is under development. The mobility for the platform is obtained by the selective actuation of one or two wires at a time. If one wire is actuated, the other two unactuated wires provide the counter effect. Similarly, if two wires are actuated simultaneously or in a differential manner, the third unactuated wire resists the movement of the platform. In an earlier work of the authors, the static displacement analysis was presented without considering the effect of unactuated wires. In this contribution, the force-displacement analysis is presented considering the effect of both actuated and unactuated wires. Subsequently, an attempt has been made to obtain a generalized approach from which six types of actuation methods are identified using a group of conditional parameters. Each method leads to a set of large deflection expressions suitable for a particular actuation method. As the large deflection expressions derived for the mechanism are nonlinear and involve interdependent parameters, their simplified form using a parametric approximation have also been obtained using Howell's algorithm. The generalized approach and the solution algorithm developed can be applied to any kind of compliant mechanism having large deflection capabilities, including planar and spatial MEMS devices and stability analysis of long slender columns supported by wires or cables. The procedure developed is also suitable for the static analysis of spatial compliant mechanisms actuated by multiple SMA actuators. � 2009 IOP Publishing Ltd.

The existing procedures for estimating short-term deflections, in prevailing codes, are based on empirical formulations of the effective moment-curvature relation. A comparison of codes shows considerable disparities in the prediction of the cracking moment, moment-curvature and load-deflection behaviour. Experimental studies on six one-way slab specimens reveal that, among the various methods, Euro code 2 method of calculating the cracking moment shows good agreement with the test results, whereas ACI 318 method of calculating deflections shows a load-deflection behaviour trend that is closest to the experimental curve, but with a higher slope. Based on the experimental results, an improved procedure is proposed, which adopts the Euro code 2 cracking moment formula combined with a modified ACI 318 code formula.

Mensmodellen worden veelal toegepast bij het ontwerpen en testen van werkplekken. Echter de nauwkeurigheid van de systemen is niet bekend. Er is dan een kans dat er (dure) fouten worden gemaakt. Om achter die nauwkeurigheid te komen is een procedure opgesteld om mensmodellen te testen

Mensmodellen worden veelal toegepast bij het ontwerpen en testen van werkplekken. Echter de nauwkeurigheid van de systemen is niet bekend. Er is dan een kans dat er (dure) fouten worden gemaakt. Om achter die nauwkeurigheid te komen is een procedure opgesteld om mensmodellen te testen

Steady-state vibrations of periodically supported structures under a moving load are analytically investigated. The following three structures are considered: an overhead power line for a train, a long suspended bridge and a railway track. The study is based on the application of so-called `periodicity condition', which implies that the shape of a structure is repetitive in time with space translation equal to the distance between neighboring supports. Main attention in the paper is paid to the effect of the load velocity on dynamic response of the structures. It is shown that the higher the load velocity, the wider the deflection field. Deflection of structures grows as the load velocity increases. This grow, however, can be not monotonical due to appearance of critical velocities related to resonances on sub-harmonics of a periodic structure.

Steady-state vibrations of periodically supported structures under a moving load are analytically investigated. The following three structures are considered: an overhead power line for a train, a long suspended bridge and a railway track. The study is based on the application of so-called `periodicity condition', which implies that the shape of a structure is repetitive in time with space translation equal to the distance between neighboring supports. Main attention in the paper is paid to the effect of the load velocity on dynamic response of the structures. It is shown that the higher the load velocity, the wider the deflection field. Deflection of structures grows as the load velocity increases. This grow, however, can be not monotonical due to appearance of critical velocities related to resonances on sub-harmonics of a periodic structure.

Experimental investigations are carried out up to collapse on eighteen stiffened steel plates having initial imperfections under uniaxial compression with simply supported boundary conditions on both loading and unloading edges. The thickness of the flange plates is varied as 4 mm and 5 mm respectively. Three types of commercially available open section rectangular flats are used as stiffeners. Six panels without cutout, six panels with square cutout which extends the full width in between stiffeners (d/b=1.0), four panels with rectangular cutout (d/b=1.5) and two panels with reinforced rectangular cutout are fabricated. The initial geometric imperfections such as plate imperfection ?(x), overall imperfection of the whole panel ?(sx) and torsional imperfection in stiffener ?(sy) are measured for all panels fabricated. The axial deformation of the whole panel, out-of-plane deflections and strains along the midsection of the panels measured during the tests is discussed. The reduction in strength of the panels due to the presence of square cutout, rectangular cutout and increase in strength due to reinforcement around rectangular cutout are calculated based on the experimental observations.Experimental investigations are carried out up to collapse on eighteen stiffened steel plates having initial imperfections under uniaxial compression with simply supported boundary conditions on both loading and unloading edges. The thickness of the flange plates is varied as 4 mm and 5 mm respectively. Three types of commercially available open section rectangular flats are used as stiffeners. Six panels without cutout, six panels with square cutout which extends the full width in between stiffeners (d/b=1.0), four panels with rectangular cutout (d/b=1.5) and two panels with reinforced rectangular cutout are fabricated. The initial geometric imperfections such as plate imperfection ?x, overall imperfection of the whole panel ?sx and torsional imperfection in stiffener ?sy are measured for all panels fabricated. The axial deformation of the whole panel, out-of-plane deflections and strains along the midsection of the panels measured during the tests is discussed. The reduction in strength of the panels due to the presence of square cutout, rectangular cutout and increase in strength due to reinforcement around rectangular cutout are calculated based on the experimental observations.

The effect of shear deformation on deflection and shear deformation together with rotatory inertia on natural and cross over frequencies of curved beams are obtained using a simple cubic linear beam element having 4 degrees of freedom per node viz u, w, ? and ?. Studies are carried out on beams with all classical boundary conditions. From the results obtained for static and free vibration problems with different curvatures and slenderness ratios, it is seen that this element is suitable to analyse any curved beam problem. Numerical results obtained without including the effect of shear deformation and rotatory inertia are made use of to quantify their effect on the static and free vibration behaviour of curved beams. ? 1998 Elsevier Science Ltd. All rights reserved.

European Recommendations exist which provide calculation rules to determine the strength and stiffness of sandwich panels composed of two metal faces with a foam in between. In case of openings in such panels (e.g. for windows) an influence will appear with regard to the stiffness and loadbearing capacity. At the institute TNO Building and Construction Research this item has been studied (numerical and experimental) which has resulted in simple design rules in addition to the before mentioned calculation rules for panels without openings. The program has been executed with financial support of the European Conmunity for Coal and Steel together with a number of Dutch panel manufacturers.

European Recommendations exist which provide calculation rules to determine the strength and stiffness of sandwich panels composed of two metal faces with a foam in between. In case of openings in such panels (e.g. for windows) an influence will appear with regard to the stiffness and loadbearing capacity. At the institute TNO Building and Construction Research this item has been studied (numerical and experimental) which has resulted in simple design rules in addition to the before mentioned calculation rules for panels without openings. The program has been executed with financial support of the European Conmunity for Coal and Steel together with a number of Dutch panel manufacturers.

The analysis of laterally loaded piles in soft clay is carried out idealising the pile as beam elements and the soil by nonlinear inelastic spring elements modeled with elasto-plastic sub-elements. The nonlinear hyperbolic model for static load condition is developed based on the undrained shear strength and modulus of subgrade reaction. An iterative procedure is adopted to perform a nonlinear finite element analysis and the effect of static lateral load on deflection is studied. Based on the lateral deflection at the end of first cycle (static load), the degradation factor is assumed and the p-y curve is modified. The cyclic load analysis is carried out using the static analysis program idealising the soil by modified p-y curve, which considers the effect of number of cycles and magnitude of cyclic lateral load. The results of the proposed analytical model compare well with the published experimental results, on piles subjected to one-way cyclic loading for different magnitude of cyclic lateral load and number of cycles. Copyright ? 1996 Elsevier Science Ltd.

The transient response of a cantilever beam is investigated for the stresses and displacements. The study is carried out for short and long duration impulse loads. The effects of impulse duration, damping and location of application of load are studied. The deflection and the stress histories and corresponding frequency responses are presented for various parameters. ? 1995 Academic Press. All rights reserved.

Fatigue failure invariably occurs at the root in hydroformed bellows, as the hydroforming process does not cold work the root region and raise yield point there, as it does in other regions. Both elastic and plastic analyses confirm this by predicting that the yield criterion is first satisfied in the root region during deflection. On the other hand, the roll-forming process imparts a substantial amount of cold work to the root of the bellows. A judicious combination of hydroforming and roll-forming processes is examined here therefore as a viable alternative (as opposed to individual routes), to enhance the fatigue life of austenitic steel bellows for low-pressure, low-temperature applications. This combination process has the added merit that bellows with extra-deep convolutions can be formed as replacements to costlier diaphragm-type bellows and for applications having space restrictions. Whilst testing the bellows for fatigue, it is noted that corrugations do not share the total movement equally, this phenomenon appearing to be a major cause for the scatter in values obtained in life tests. Investigation reveals that a correlation exists between this unequal sharing of movement and fatigue life. Based on these observations a new non-destructive stretch test is proposed with which original life estimates can be refined.

A detailed study has been conducted on the effect of different types of variations of thickness profiles on the amplitudes of deflection and the dynamic bending stress of a cantilever beam under a point harmonic load. The response has been calculated for excitation frequencies corresponding to the first three natural frequencies. In each case the results obtained for different types of thickness variations are compared with those obtained for a uniform thickness beam. It is observed that considerable reduction in amplitude and/or bending stress can be achieved by proper selection of thickness variation. ? 1994 Academic Press. All rights reserved.

The paper presents a displacement incrementation procedure to handle multiple loadings in post-buckling analysis of structures by Dynamic Relaxation (DR). This procedure is generalized and a ‘variable-arc-length’ method is proposed to automate the tracing of load-deflection path. The resulting algorithm exactly traces limit points and can handle ‘snap-through’ or ‘snap-back’ problems. The efficiency of the proposed method is demonstrated by typical examples of truss, beam and shell structures.

Mooring dolphins are generally supported on group of piles and these piles are subjected to significant lateral loads due to mooring pull of the berthing vessel and wind and wave action. In this investigation, the behaviour of pile groups under lateral load has been studied by conducting static load tests on instrumented model pile groups embedded in clayey soil, changing the spacing between piles, number of piles and the arrangement of piles in the group. The results indicated that the capacity of a pile group depends not only on the spacing of piles in the group but also on the arrangement of piles with reference to the direction of loading. For cyclic load application, the deflections are observed to stabilize after some cycles depending on the cyclic load level. The post cyclic behaviour of the piles has been explained in terms of the changes in the soil strength behaviour during cyclic loading.

A thermomechanical model is presented for predicting the time-dependent deflections of cellular FRP slab elements subjected to mechanical loading and fire from one side. The model comprises temperature-dependent mechanical property sub-models for the Young's modulus, viscosity and coefficient of thermal expansion. Two different thermal boundary conditions were investigated: with and without liquid-cooling of the slab elements in the cells. A finite difference method was used to calculate the deflection at each time step. Deflections resulting from stiffness degradation due to glass transition and decomposition of the resin dominated over those resulting from viscosity and thermal expansion. The predicted total deflections compared well with the measured results over a test period of up to 2 h. The failure mode of the non-cooled specimen could be explained. © 2009 Elsevier Ltd. All rights reserved