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Wood is a renewable source of structural material with high relative strength/weight, low energy production, which kidnaps and stores carbon in its production. The large use of wood is due to its special qualities as raw material for other products manufactured in residential construction or major works such as bridges, has been widely used in roofing for industrial and commercial buildings. Commercially there are limitations on the length of the wood, resulting from the extraction of tree trunks, thus requiring the adoption of binding elements is the use of self-tapping screws efforts required by side and which can be axial, shear, tensile or compression. Whereas in Brazil does not yet exist and the promising future of the product, this research aims to study the behavior of self-tapping screws together with Brazilian reforestation species ofPinusoocarpaandLyptus(softwood and hardwood). Rothoblaas self-tapping screws had a good penetration in both woods without requiring pre-drilling, the species of Lyptus wood showed the highest values of strength and the inclination of the screws, at 45 degrees showed the best results on either species of wood.

This paper encompasses the work from numerical model by investigating the compression response of CFRP composite cylinder shells. The aim of this paper is to improve the reliability of NASA SP-8007 design guideline. The cylinder geometrical imperfections were tested through numerical modelling and validate with the experiment results. Good results comparison has been obtained through the work with small amount of errors. The cylinder shell load carrying capacity has been improved by average of 56% through imperfection study. This work builds confidence in the future use of non-linear finite element for the design of composite cylinder subjected to axial compression load.

The paper reports on the activities of the RILEM technical committee “Reinforcement of Timber Elements in Existing Structures”. The main objective of the committee is to coordinate the efforts to improve the reinforcement practice of timber structural elements. Recent developments related to structural reinforcements can be grouped into three categories: (i) addition of new structural systems to support the existing structure; (ii) configuration of a composite system; and (iii) incorporation of elements to increase strength and stiffness. The paper specifically deals with research carried out at the Bern University of Applied Sciences Switzerland (BFH), the University of Minho Portugal (UniMinho), and the University of Trento Italy (UNITN). Research at BFH was devoted to improve the structural performance of rounded dovetail joints by means of different reinforcement methods: i) self-tapping screws, ii) adhesive layer, and iii) a combination of selftapping screws and adhesive layer. Research at UNITN targeted the use of “dry” connections for timber-to-timber composites, specifically reversible reinforcement techniques aimed at increasing the load-bearing capacity and the bending stiffness of existing timber floors. At UniMinho, double span continuous glulam slabs were strengthened with fibre-reinforced-polymers. All three examples demonstrate the improved structural performance of timber elements after reinforcing them., The research on RDJ was funded by BFH and supported by the staff at the BFH " tech-park" Huesser Holzbau AG and ArundaR. The research at UNITN was carried out by the Timber Research Group (in particular by M. Piazza, R. Tomasi, I. Giongo) within the framework of the RELUIS Project 2011-2013, which is financed by the Italian Emergency Management Agency (Dipartimento della Protezione Civile) and supported by Rothoblaas srl.

The paper is related to the San Torcato Church, in Guimarães, Portugal. At the moment, the church has significant structural problems due to soil settlements. Cracks can be observed on the main and the lateral façades, the bell-towers are leaning, and the arches in the nave exhibit a failure mechanism with cracks and vertical deformations. Non-stabilized phenomena are present in the structure. To stabilize the damage, a structural intervention is planned to occur soon and the church is already monitored to follow the intervention. The paper clearly presents the problem with emphasis to the dynamic analysis carried out before the structural strengthening, namely: the experimental tests with output-only techniques for frequencies, damping and mode shapes estimation, FE model updating analysis and dynamic monitoring

Cracks in railway prestressed concrete sleepers are often caused by the infrequent but high magnitude impact forces. These impact forces are attributed to the wheel or rail abnormalities, e.g. wheel flat, corrugation, dipped joint, etc. The emphasis of this paper is placed on the corresponding fractures of railway prestressed concrete sleepers in track systems under the probabilistic impact loadings. The statistical data of impact loadings in Central Queensland have been obtained through the collaborative project under the research framework of the Australian Cooperative Research Centre for Railway Engineering and Technologies. It is found that for the heavy haul railway network, the track structures, especially the concrete sleepers, may experience the impact loading from 400kN up to 800kN. The corresponding probabilities of such load occurrences are ranging from one in twenty years to one in thousands of years. It is very important for the design and maintenance perspectives to investigate the impact behaviour of concrete sleepers under the impact loadings. This paper presents the impact fractures of railway prestressed concrete sleepers under the single impact loading associated with the probability of occurrence in the soft track environment. Visual interfacial cracks have been evaluated for the crack length and width along the sleepers in relation to the probability of load occurrence.

Reachstacker is an indispensable handling machinery, it will inevitably lead to unbalanced force at the job site. This paper does transient dynamics analysis for the spreader mechanism, which is one of the most significance key components. We get dynamic response of the spreader in lifting instant, results not only provide a reference for designers to understand the mechanical characteristics of spreader comprehensively, but also bedding for the future research.

Selectively induced compressive residual stress depth profiles are gaining increasing importance as design tool for internally pressurized components. Hydraulic Autofrettage (AF) is a well-known manufacturing process to induce pronounced compressive residual stresses. However, AF does not stand alone in the technical process chain. In this paper, results from neutron diffraction experiments performed on thick-walled cylinders are presented and compared to finite-element simulations with Abaqus/CAE. The impact on the final residual stress depth profile after pre-machining, Autofrettage and post-machining is discussed.

This paper investigates experimentally and numerically the degree to which the stress relaxation in shot-peened simple geometric features of steel turbine materials can be modelled by using an understanding of simple eigenstrain distributions. The residual stress is determined as the elastic response of whole component when the plastic strains caused by shot peening is incorporated as an eigenstrain in an appropriate finite element (FE) model. The application of a subsequent live load is then modelled as an additional load step in the FE model which will superpose the effect of this loading on the residual stress field. The results show that the eigenstrain approach is particularly useful in predicting residual stress relaxation in shot-peened components.

Layer removal method is an experiment method which is used to calculate the average stress indirectly by deformation of the specimen. However, in the experiment, some certain predeformation can be caused after each clamping, which can affect the accuracy of the test data, and make the deformation data larger. Based on the comparison of the simulation calculation, this paper builds an amended function by fitting the deformation error, which solves the deviation caused by larger deformation on stress calculation while the specimen is milled by layer, that is to say, the stress calculation model can be compensated by this function. This method can make the experimental calculation model more accurate.

During the revision of the individual parts of a hydroelectric power plant the cracks in the pins of quick operating and revision flap valves of Francis turbine were found. Our department has been approached with a request to investigate the causes of these cracks. This paper deals with the complex analysis of influential factors, especially the measurements of residual stresses by hole-drilling method, in order to reveal the factors causing the cracks in the pins.

This paper presents static fatigue laboratory experiments conducted in three different configurations. The experiments are designed so as to cause delayed tensile failure in dry Gabbro specimens after the sustained application of a static subcritical load. Results from the static fatigue experiments give a time to failure of the specimen related to the applied static load. In the presented experiments, results spanning up to six orders of magnitude of time to failure were collected for three-point bending, four-point bending, and indirect tensile (Brazilian) specimens. The data supports an exponential relationship between tensile stress and time to failure, noting that a power law relationship is also supported by the data. The salient difference among the configurations is hypothesized to be the size of the region of the specimen that is subjected to a close approximation of the maximum tensile stress. The time to failure at a given nominal tensile stress, the decrease in time to failure associated with a given increase in stress (i.e. the slope in a semi logarithmic plot), and the magnitude of the scatter of the data about the best-fit curve are all observed to correlate inversely with the nominal size of the region subjected to the maximum tensile stress.

Strip profile control during rolling is required to assure the dimensional quality of rolled thin strip is acceptable for customers. Throughout rolling, the strip profile is controlled by using the advanced shape control rolling mill, such as the combination of work roll crossing and shifting during asymmetrical rolling, the one of the valuable methods to control the strip profile quality in rolling process. In this paper, the influences of cold rolling parameters such as the crossing angle and axial shifting value of work rolls on the strip profile are analysed. The strip shape control is discussed under both symmetrical and asymmetrical rolling conditions. The obtained results are appropriate to control the rolled thin strip profile in practice.

To know the physical and mechanical properties of wood to be employed as structural elements in is an important factor for its use in a rational way. The connections between members of timber structures are also relevant topic once local stress concentrations can occur and safety must be seriously taken in account. Brazilian Code ABNT NBR 7190: 1997 "Design of Timber Structures" provides guidelines for connections calculation based on two alternative limit states: wood strength to embedment or bending of the bolt. The purpose of this paper is estimate the strength to embedment of Pinus sp. to bolts in three directions with respect to the grain: parallel, perpendicular and inclined at 45o. Specimens obeying requirements of Brazilian Code related to bolts diameter (10mm) were prepared and tested. The embedment strength in parallel direction to the fiber was the highest and the failure modes were more frequent crushing and cleavage.

Shear failure is often found for masonry structure when subjected to complex loading. This paper presents the numerical analysis of shear strength test on triplet masonry specimens under different normal compressive stresses. Two different models were produced using a commercially available finite element analysis package ANSYS. The first model is a continuum model with the brick unit modeled as linear elastic material, while the mortar joints are modeled using a Drucker-Prager (DP) material or a concrete material. In the second model, the mortar joints as well as the brick/mortar interfaces were represented by a series of contact elements, and the Mohr-Coulomb failure surface was employed by these contact elements. Comparisons with the experimental results show that both models give satisfactory predictions for the maximum failure load, while the finite element model with interfaces has a better performance in terms of the load displacement response.

Coatings play an important role in a variety of engineering applications protecting metallic or ceramic substrates against oxidation, heat penetration, wear and corrosion. One of the contributing factors to structural or functional failure of coatings is a mismatch of material properties between the coating and substrate at the coating/substrate interface. The concept of Functionally Graded Material (FGM) is actively explored in coating design for the purpose of eliminating this mismatch and improving coating performance and integrity. This paper presents analysis of the mechanical behavior of functionally graded coatings using commercial finite elements software ABAQUS in which user implemented graded finite elements have been employed. The model is used to carry out a comparative study of three-dimensional stress and displacement fields in the coated plates with homogeneous and functionally graded coatings.

The monitoring of timber structures exposed to natural climate fluctuations during their service life is an important topic for both their serviceability and safety. Numerical methods based on the recent advances in hygro-thermal modelling of wood can integrate the usual sensor-based monitoring techniques by reducing the maintenance costs for timber structures. In this paper, a 3D full coupled analysis based on the multi-Fickian theory with sorption hysteresis of wood is implemented in Abaqus FEM code by defining a new finite element in a user subroutine. To verify the method, the hygro-thermal behaviour of a glulam beam tested in laboratory under variable humidity within a previous research is analysed and the numerical values of moisture content are found to be in agreement with the experimental data. Furthermore, a numerical case-study of a glulam cross section under real climate variations is presented and the related results show the capability of the method to predict the moisture states in each points of the glulam member under continuously variable humidity and temperature.

On the basis of the theoretical study and application of ordinary steel-encased concrete composite beam, this paper will focus on a new high-strength steel-encased concrete composite beam, and mainly studies high-performance steel Q420 and Q460, as well as high-strength concrete C60 and C80. Besides, an experimental study of 5 simply-supported beams is made, and the load-deflection curves of new SCCB are analyzed. The calculation formula of load which changes with depth of section and bending strength of the cross section is also analyzed. It is suggested that the calculated results announced should be identical with the experimental results.

Timber poles are commonly used for telecommunication and power distribution networks, wharves or jetties, piling or as a substructure of short span bridges. Most of the available techniques currently used for non-destructive testing (NDT) of timber structures are based on one-dimensional wave theory. If it is essential to detect small sized damage, it becomes necessary to consider guided wave (GW) propagation as the behaviour of different propagating modes cannot be represented by one-dimensional approximations. However, due to the orthotropic material properties of timber, the modelling of guided waves can be complex. No analytical solution can be found for plotting dispersion curves for orthotropic thick cylindrical waveguides even though very few literatures can be found on the theory of GW for anisotropic cylindrical waveguide. In addition, purely numerical approaches are available for solving these curves. In this paper, dispersion curves for orthotropic cylinders are computed using the scaled boundary finite element method (SBFEM) and compared with an isotropic material model to indicate the importance of considering timber as an anisotropic material. Moreover, some simplification is made on orthotropic behaviour of timber to make it transversely isotropic due to the fact that, analytical approaches for transversely isotropic cylinder are widely available in the literature. Also, the applicability of considering timber as a transversely isotropic material is discussed. As an orthotropic material, most material testing results of timber found in the literature include 9 elastic constants (three elastic moduli and six Poisson's ratios), hence it is essential to select the appropriate material properties for transversely isotropic material which includes only 5 elastic constants. Therefore, comparison between orthotropic and transversely isotropic material model is also presented in this article to reveal the effect of elastic moduli and Poisson's ratios on dispersion curves. Based on this study, some suggestions are proposed on selecting the parameters from an orthotropic model to transversely isotropic condition. © (2013) Trans Tech Publicutions, Switzerland.

The paper presents a novel concept and a prototype of a diagnostic tool for in-situ assessment of timber in existing structures and buildings. The device enables direct determination of conventional compressive strength and modulus of deformation in arbitrary depth along timber profile. The measurement of the stress-deformation relationship is performed in a prepared hole of a very small diameter by means of a special small size symmetrical loading jack. Testing and verification of the new device behaviour during loading of wood along the fibres has been carried out on fir which is the most frequent wood species in European buildings. The comparison of stress-strain diagrams acquired by means of the new device with those measured in compliance with the European standard for testing of wood shows a very good correlation including the determination of the compressive strength values. This semi-destructive method causes a very gentle damage and can be also used for the assessment of historic timber structures.

This paper analysis the causes dynamically loaded screws failure, using the structural analysis of mechanical properties and numerical simulation. The comparison with the new unbroken screws, which were not in use, has been done to determine the condition of the broken (dynamically loaded) ones. Analysis was performed, according to the following test methods and activities: non-destructive testing, visual inspection, radiographic testing, chemical analysis of screws sample materials, mechanical properties of screws' materials. Structure analysis of screws materials: Testing macrostructure (light optical microscope, SEM-EDS) examination of the microstructure (light optical microscope, SEM-EDS), fractographic examination. Numerical simulation of the stress state of the dynamically loaded screws was done in CATIA software package, and it was identical to the bolt loads, during service exploitation. The results between numerical simulation and structural analysis were quite coinciding - the difference is about 8-10%, which is pretty good for these types of experiments. Such an overlap, says that the stress value at the very screws is reliable and give us a true picture of loadings. Structural mechanical tests have shown a very pronounced effect of dynamic loads, that large shear stress shows also as a good agreement, where between the stresses, obtained by numerical simulation and structural mechanical testing. Analysing the results, obtained by numerical simulation and structural mechanical testing were performed with the redistribution of critical stresses, and proposal for the structure optimization. The comparative analysis methods have been provided the precise prediction of fracture appearance and made possible to define the preventive measures.

Creep damage is one of the serious problems for the high temperature industries and computational approach (such as continuum damage mechanics) has been developed and used, complementary to the experimental approach, to assist safe operation. However, there are no ready creep damage constitutive equations to be used for predicting the lifetime for this type of alloy, particularly for low stress. This paper presents an analysis of the cavity nucleation, growth and coalescence mechanism of 9Cr-1Mo-VNb steel (P91 type) under high and low stress levels and multi-axial stress state.

The field of polymers in concrete is consolidated in the construction industry. The future of polymers in concrete is governed by the synergic interaction between these materials, in order to contribute significantly towards a more sustainable construction. Concrete-polymer composites (C-PC) have excellent mechanical and durability properties. Appropriate combination of polymers and classical construction materials provides opportunities for innovative applications and systems. This paper highlights the innovations and new approaches presented at the 13th International Congress on Polymers in Concrete in Madeira, Portugal, 2010 and at the 7th Asian Symposium on Polymers in Concrete in Istanbul, Turkey, 2012. The new trends presented are related with the micro and nanostructure, properties, test methods and applications of concrete-polymer composites.

This paper presents the results of the research undertaken by the authors in the frame of the postdoctoral program 4D-POSTDOC. After a short introduction on the actual status of structural design of airport pavements including geometrical and loading characteristics of complex loading gears, the modeling and the structural design of airport rigid pavements, constructed with conventional and various recycled materials, using the finite element method, is described. The main objective of this research program was to elaborate a design method which, beside the complex landing gear including six footprint tires, all specific parameters related with the recycled materials and with conventional and reinforce rolled compacted concrete (RCC) technologies are included. Finally, practical design diagrams for structural design of the concrete slabs, including their specific correlation function, used for the construction of the Airbus-A380 runway are presented., (undefined)

So far, the industrial application of ultrasonic vibration assistance has been successful in continuous machining process such as turning process where ultrasonic vibration velocity is much higher than cutting velocity. Recently, vibration assistance has been experimentally investigated to the intermittent milling process mainly for feed and cross- feed directions. This paper focuses on the effect of ultrasonic vibration assistance in spindle axial direction for improvement of machined surface. With the designed ultrasonic vibration assisted milling process with 39.7 kHz and a few micro-meter amplitudes, workpiece vibrates along spindle axial direction while different RPMs and feed rates are applied. The axial directional vibration assistance acts as additional cutting motion which further reduces the leftover surface error. Experimental results validate that surface roughness can be improved from 20 % to 65 % for the tested conditions. Apparently chatter marks of the milling process are reduced with the help of the axial ultrasonic vibration assistance.

[EN] The aim of this paper is to introduce a method to reduce the weight in structures which are subjected to multiple restrictions like deformation, max allowable stress, natural frequency, etc. The method is shown through the analysis of an aluminum bracket, whose maximum stress and deformation is well defined. The analysis is done using the Structural and Design of Experiments modules of Ansys Workbench v12.1. As result of the method a weight reduction of 50,2% is achieved. © (2012) Trans Tech Publications.

Diagrid structures are widely used for today’s tall buildings due to their distinguished architectural aesthetics in any existing urban context and structural efficiency in carrying lateral loads. With prevalent emergence of complex-shaped buildings throughout the world, this paper investigates structural efficiency of diagrid structures employed for complex-shaped tall buildings, such as twisted, tilted and freeform towers. For each complex form category, tall buildings are designed with diagrid systems, and their structural efficiency is studied in conjunction with building forms. In order to investigate the impacts of various important geometric configurations of complex-shaped tall buildings, parametric models are generated using appropriate computer programs, and the models are exported to structural engineering software for design and analyses. Based on the study results, structural efficiency of diagrids for tall buildings of each complex form category is estimated.

[EN] This part analyzed GFRP rebar's research situation, summarized its behaviuor as internal reinforcement for concrete structures. The research has been developed over recent years, however the rules and standard codes for design RC concrete structures with these rebars not consider that the internal reinforcement can work in compression. This paper presents the development of the research to get a new kind GFRP rebar for work as internal reinforcement of concrete structures, with an innovative design for work both in tension and compression, and their mechanical properties: strength, bond,.... © (2012) Trans Tech Publications.

International audience; To better understand the complex phenomena involved in the cutting process is to better qualify the behaviour law used in the simulatiotrn of machining processes (analytical and finite element modeling). The aim of this paper is to present the choices made regarding the behaviour law in this context, indeed, commonly used behaviour laws such as Jonhson-Cook can bring unsatisfactory results especially for high strain and large deformation processes. This study develops a large deformation strain-gradient theoretical framework with hypothesis linked with to metal cutting processes. The emphasis of the theory is placed on the existence of high shear phenomena creating a texture in the primary shear band. To account for the texture, the plastic spin is supposed to be relevant in this theory. It is shown that the theory as the capability of interpreting the complex phenomena found in machining and more particularly in high speed machining.

Firstly, this paper presents an overview of DoD code [1] against progressive collapse and points out the shortcomings of the current design approaches. After that, seven experimental tests of common types of bolted steel beam-column joints under a middle-column removal scenario are presented. This study provides the behaviour and failure modes of different types of connections, including their resistances and rotational capacities in catenary action. The test results indicate that the web cleat connection has the best performance in the development of catenary action. The flush end plate, fin plate and top and seat with web angle (TSWA) connections could also deform in a ductile manner and develop catenary action prior to failure. Numerical simulations have also been conducted. Both static and explicit dynamic solvers were employed to overcome problems of non-convergence, contact, large deformation and fracture simulations. It is demonstrated that the finite element analyses give reasonable accuracy compared to the test results. In addition, an extensive parametric study was undertaken using these validated models to obtain the rotation capacities of various types of connections under catenary action. Finally, some practical design implications have been drawn up from the experimental tests and the parametric study. A new tying resistance expression is proposed to consider the effect of large rotation. If large rotation capacity is not considered in the design stage, the joints with poor rotation capacities would fail to achieve the design tying resistances. In addition, four new connection acceptance criteria of rotation capacities have been proposed to incorporate catenary action under a middle column removal scenario. The work shows that current acceptance criteria of rotation capacities for steel joints such as web cleat, fin plate, flush end plate and TSWA connections, are probably too conservative as they only consider pure flexural resistance.

This paper reports the structural behavior of precast lightweight foamed concrete sandwich panel, PLFP, subjected to eccentric loading. An experiment was conducted to investigate the structural performance of PLFP under this load. Two PLFP panels, PE-1 and PE-2 were cast with 2000 mm in heights, 750 mm in width and 100 mm in thickness. The thickness of the wall is actually a combination of three layers. Skin layers were cast from lightweight foamed concrete while the core layer is made of polystyrene. The skin layers were connected to each other by 9 mm steel shear truss connector which were embedded through the layers. Panel PE-1 was strengthened with single diagonal shear truss connectors made of 6 mm steel rebar while panel PE-2 was strengthened with symmetrical diagonal shear truss connectors of similar steel diameter. Both panels were tested under eccentric load till failure. The results showed that panel with symmetrical double truss connectors, PE-2, is able to sustain higher load compared to panel with single shear truss connector. The load-deflection profiles indicate that both panels achieved certain degree of composite action especially during the later stage of loading where the wythes tend to move in the same direction until they reached failure. The load-strain curves for both panels highlight the inconsistent distribution of surface strain along the height of panels. The overall trend of the strain curves show that they are under compression.

Shape memory alloy was firstly used commercially as a hydraulic coupling in the Grumman F14A in 1971. It is today used among others to improve structural behaviours such as buckling of composite plates in the aerospace vehicles. In this paper, finite element model and its source code for thermal post-buckling of shape memory alloy laminated composite plates is presented. The shape memory alloy wires induced stress that improved the strain energy, stiffness and thus the buckling behaviour of the composite plates. The finite element formulation catered the combined properties of the composite and shape memory alloys, the addition of the recovery stress and the temperature dependent properties of the shape memory alloys and the composite matrix. This study showed that by embedding shape memory alloy within layers of composite plates, post-buckling behaviours of composite plates can be improved substantially.

A multiscale constitutive framework for Ni-base superalloys has been developed, in which an efficient unit cell is adopted to describe the γ/γ’ microstructure morphology. The framework enables the prediction of the deformation and the creep and fatigue damage accumulation in CMSX-4 for a range of temperatures and stress levels. Moreover, the material microstructural degradation due to rafting and isotropic coarsening can be simulated, and the effects of this degradation on the alloy mechanical response can be quantified. The present paper focuses on the application of the model to real gas turbine components. A high pressure turbine blade finite element model is used to demonstrate the computational efficiency of the multiscale framework. Moreover, the location of critical regions and the life time are shown to differ from the results obtained from classical models that neglect the microstructure evolution.

This paper aims to present an alternative design method for remote wireless shape control of laminated composite structures using topology optimization. The photostrictive material is introduced to implement the active control of the structure by making use of its photostriction mechanism, which is actually the superposition of photovoltaic effect and converse piezoelectric effect when exposed to the illumination of near ultraviolet light. The finite element formulation including multiphysics effects of photovoltaic, pyroelectric and thermal expansion is developed to model composite structures of ferroelectric materials, based on the Mindlin plate theory of first-order shear deformation. The topology optimization method is used to seek the optimal topologies for material layouts of both the smart actuation and elastic host layers. A typical numerical example is used to demonstrate the feasibility of this method in shape control of composite structures.© (2011) Trans Tech Publications, Switzerland.

Compliant components such as large sheet metal components are commonly used in various products including automotive, aircraft and home appliances. Because of part-to-part variations, deformation and stresses are induced in the assembly process. An approach to the assembly tolerance analysis of compliant structures is presented in this paper. Given component deformation, assembly deformation and stresses are derived by finite element analysis (FEA). The influence of component deformation on assembly deformation and stresses is studied by response surface methodology (RSM), and a regression model is developed. Using the developed regression model, Monte Carlo simulation was conducted to study assembly tolerance and stresses. This approach is illustrated by an example.

Safe extrapolation of short-term creep data requires development of creep models where (a) the constitutive laws are physics based, and (b) majority of model parameters are calculated rather than empirically fitted. This paper details the structure of such a physics-based creep model and its application to DS GTD-111TM superalloy. The constitutive creep law is derived from the kinetics of dislocation-particle interactions in the presence of thermal activation. This constitutive creep law is further coupled with the evolution kinetics of controlling microstructural parameters and associated damages. The model is expected to provide vital inputs for component design as well as remaining life assessment. (GTD-111TM is a trademark of the General Electric Company).

The ability of mortarless wall to restrain/sustain lateral load become important aspect to be consider in the design of wall. Therefore, this paper presents analyses of mortarless wall subjected to in-plane combined loading using finite element programs. The developed 2D finite element program is used in this research. The finite element models are developed based on micro modelling approach where each constituent of masonry (block and dry joint) connected each other by joints at their actual position. Eight nodded isoparametric plane element and six nodded zero thickness isoparametric interface element are used to represent block unit and dry joint respectively. The developed models are analysed under nonlinear environment. The most relevant results concern the strength response of the dry joint masonry walls subjected to in-plane combined compressive and shear loading. The results of finite element analysis compared with corresponding experimental results and its show good agreement. Parametric study also performed to consider the important parameters that effect the design of wall under combined loading. Significant features of the structural behaviour, ultimate capacity and observed failure mechanisms are addressed and discussed.

Built-up sections are used to resist load induced in a structure when a single section is not sufficient to carry the design load for example roof trusses. In current North American Specification, the provision has been substantially taken from research in hot-rolled built-up members connected with bolts or welds [1]. The aim of this paper is to investigate on built-up back-to-back channels stub columns experimentally and theoretically using Effective Width Method and Direct Strength Method. Compression test was performed on 5 lipped channel and 5 back-to-back channels stub columns fabricated from cold-formed steel sheets of 1.2mm thicknesses. The test results indicated that local buckling is the dominant failure modes of stub columns. Therefore, Effective Width Method predicts the capacity of stub columns compared to Direct Strength Method. When compared to the average test results, results based on EWM are 5% higher while results based on DSM are 12% higher for stub column.

This work focuses on the seismic risk evaluation of the Concordia temple, situated in the Valley of the Temples in Agrigento (Italy). In the paper a general methodology to assess the seismic vulnerability, to be applied also to any kind of structures composed of stone blocks, is proposed. The vulnerability assessment has been conducted by means of equivalent nonlinear static analyses along the principal directions of the structure and the subsequent identification of equivalent single degree of freedom systems. Furthermore, the seismic vulnerability has been expressed both in a deterministic and a probabilistic context by evaluating the severe damage probability.

This paper presents an investigation about the capabilities of simplified kinematic limit analysis for the safety evaluation and for the design of strengthening of masonry historical buildings. Limit analysis allows, with a reduced number of mechanical properties and for a given ultimate condition of the structure, affordable safety analysis and design of strengthening to the practitioners. Masonry buildings subjected to earthquake show in most cases local failure mechanisms rather than global failure mechanisms due to the lack of integrity of structure. For this reason, simplified kinematic limit analysis has been accepted as a method to design the strengthening of masonry buildings, according to the Italian Ordinance (O.P.C.M. 3431). To validate the applicability of this method, its results had been compared with those provided by three dimensional macro block limit analysis (Bustamante, 2003) for the Via Arizzi house. It is worth noting that results of simplified kinematic limit analysis provided similar results as those achieved by 3D macro block. Also this method was implemented to seismic safety assessment of Tekyeh Amir Chakhmagh in Iran based on the results obtained for the out of plane and in plane behaviour of walls. Tekyeh Amir Chakhmagh is an early 19th century tiled edifice that was built to serve as grand-stand for watching religious rites and also provided an imposing entrance to Amir Chakhmagh bazaar. This stunning three-story facade of the building is one of the most recognizable and unusual buildings in Iran.

The Franciscan church of La Peregrina in Sahagún (Spain) was founded in the 13th Century. It has undergone many transformations and additions throughout its history. The most important were carried out in the 17th Century when the church was converted to the Baroque style. The apse vaults were demolished and new timbrel vaults were built hiding the Mudéjar windows. In the nave, the transverse arches that supported the modern roof were also demolished, internal counterforts were built and new barrel timbrel vaults with lunettes, erected. Eventually, an oval dome was built on the transept. Recent restoration work will give the building a new use. The project aims to recover the Mudéjar apse with its windows providing natural light to the presbytery. This involves the demolition of the Baroque vaults above the presbytery (a barrel vault terminated with a semi-dome). The oval dome will lose some buttressing to the side of the apse and an expertise was required to assess the feasibility of the operation. In the present paper the structure of the church will be described and the analysis of the oval dome with and without the presbytery vaults will be explained.

The large deformation analysis is one of major challenges in numerical modelling and simulation of metal forming. Because no mesh is used, the meshfree methods show good potential for the large deformation analysis. In this paper, a local meshfree formulation, based on the local weak-forms and the updated Lagrangian (UL) approach, is developed for the large deformation analysis. To fully employ the advantages of meshfree methods, a simple and effective adaptive technique is proposed, and this procedure is much easier than the re-meshing in FEM. Numerical examples of large deformation analysis are presented to demonstrate the effectiveness of the newly developed nonlinear meshfree approach. It has been found that the developed meshfree technique provides a superior performance to the conventional FEM in dealing with large deformation problems for metal forming.

Boilers in power, refinery and chemical processing plants contain extensive range of tube bends. Tube bends are manufactured by bending a straight-section tube. As a result, the crosssection of a tube bend becomes oval. Using the finite element analysis (FEA) and artificial neural network (ANN), the paper presents the relationships between the plastic collapse pressures and tube bend dimensions with various degrees of ovality. It is found that as ovality increases the plastic collapse pressure decreases. Also, the reduction of plastic collapse pressure with ovality is small for a thick tube bend when compared with that for a thin tube bend.

Different possible reasons for defects have to be considered in machining light-weight aluminum structures. In the machining process, the cutting power affecting the workpiece leads to a thermo-mechanical load that can cause undesirable workpiece deformations and thus shape deviations. Moreover, the microstructure and the machined surface can be influenced, which is detrimental to the later application of the structures. Previously conducted experimental and simulative investigations, estimated the circular milling process to be the most suitable machining operation that provides the best compromise between mechanical and thermal loads compared to drilling operations [1,2]. In this paper the results of machining end-cross-sections of an aluminum profile are presented. The machining was obtained by a milling process, which is demanding, because of the low profile stiffness. For this process it is important to know the effects of machining in view of the shape deviations. By means of a Finite-Element-Analysis the deformations of the profile web can be calculated as well as validated by experiments. Based on these results, the appropriate process parameter values for end machining can be defined.

The microstructural heterogeneity and stress fluctuation play important roles in the failure process of brittle materials. In this paper, a generalized driven nonlinear threshold model with stress fluctuation is presented to study the effects of microstructural heterogeneity on continuum damage evolution. As an illustration, the failure process of cement material under explosive loading is analyzed using the model. The result agrees well with the experimental one, which proves the efficiency of the model.

In general, cracks in structural members indicate a level of serviceability of the engineering structures. Usually a hairline crack can be detected by visual inspection, crack gauge, fibre optical sensor, or laser sensor. Recently, an attempt to develop a non-destructive tool for health monitoring of prestressed concrete sleepers in railway tracks using the vibration responses has been established at the University of Wollongong, Australia. However, the fundamental understanding of the dynamic effect due to the cracks in sleepers is insufficient. This paper investigates the dynamic effect of the cracks on the vibration signatures of the railway prestressed concrete sleepers. The modal analysis has been used to evaluate the modal changes in vibration characteristics of the prestressed concrete sleepers in the frequency band between 0 and 1,600 Hz. The sample cracks have been initiated by the impulsive forces attributed to the high capacity drop impact testing machine. Comparison of the modal parameters of the intact and cracked sleepers has been highlighted in terms of natural frequencies and modal damping. This understanding will lead to further development of the economical technology to evaluate the structural integrity of railway track and its components.

Lightweight extrusion profiles with reinforcement elements are promising news in the domain of lightweight construction. The machining of them suffers from several problems: Aside from the question of choosing a suitable tool, feed rate, and milling strategy, an excessive rise in temperature could lead to stress and even a distortion due to the differing thermal expansion of the reinforcement material and the surrounding matrix material. A simulation of the milling process could, in addition to force and collision calculations, recognize this case before manufacturing. For certain milling applications like seal surfaces, a certain roughness of the manufactured surface is necessary. In many other cases, a smooth surface of very high quality is desirable. Available simulation systems usually completely lack the simulation of dynamic effects, which have a great effect on the final surface quality, and therefore are not able to predict the resulting surface quality. In this paper simulation methods are presented that are capable of simulating the dynamic behavior of the tool in the milling process and the resulting flank and ground surface structures. Additionally, a fast temperature simulation for heterogeneous workpieces with reinforcement elements, which is based on the finite difference method and cellular automata, is introduced.

Curved Profile Extrusion (CPE) is an extension of the common extrusion process and offers the possibility to manufacture three-dimensionally curved profiles. Due to the flexibility of the process different curvatures can be produced with the same setup, which makes this technique efficient especially for low volume production. The process is characterized by a controlled lateral deflection of the strand which influences the material flow in the die and causes the profile curvature. In this paper, a direct comparison of the power rating between warm bending and CPE is presented. Furthermore, the investigations concerning the choice of support strategy of the surmounting profile by a robot to increase the curvature accuracy are continued. Finally, some extensions of the equipment are explained to increase the level of process integration.

With the increasing demands of energy efficiency and environment protection, composite materials have become an important alternative for traditional materials. Composite materials offer many advantages over traditional materials including: low density, high strength, high stiffness to weight ratio, excellent durability, and design flexibility. Despite all these advantages, composite materials have not been as widely used as expected because of the complexity and cost of the manufacturing process. One of the main causes is associated with poor dimensional control. General curved composite parts are often used as the structural components in the composite industry. Due to the anisotropic material nature, process-induced dimensional variations make it difficult for tighttolerance control and limit the use of composites. This research aims to develop a practical approach for the design of general curved composite parts and assembly. First, the closed-form solution for the process-induced dimensional variations, which is commonly called spring-in, was derived. For a general curved composite part, a Structural Tree Method (STM) was developed to divide the curve into a number of pieces and calculate the dimensional variations sequentially. This method can be also applied to an assembly of composite parts. The approach was validated through a case study. The method presented in this paper provides a convenient and practical tool for the dimensional and tolerance analysis in the early design stage of general curved composite parts and assembly, which is extremely useful for the realization of affordable tight tolerance composites. It also provides the foundation of Integrated Product/Process Development (IPPD) and Design for Manufacturing/Assembly (DFM/DFA) for composites.