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Abstract

Calculation of pullout capacity of anchoring concrete cylindrical block by finite element method is carried out. 3D model of the block assumes its free rotation. Alternative solutions with one and two pulling forces attached at different heights of the block are considered. Dependency of the ultimate pulling force on the points of its application, the block’s embedment depth as well as contact friction are investigated. Results of FE analysis and simple engineering estimations are compared. The maximum pullout resistance results from FE analysis when the rotation of the block is prevented.

interesting parts of the design process for the specific case. Namely, time dependent properties of the materials have been considered, and extensive “staged construction” analyses have been carried out to ensure safety in each phase of the complex life of the bridges, while at the same time guaranteeing significant cost savings. Keywords: steel-concrete composite deck, FE analysis, seismic isolation, time-dependent material properties, staged construction 1. INTRODUCTION The two viaducts share the same cross section and statical scheme, while differing

Abstract

Split Hopkinson pressure bar (SHPB) is one of the most important and recognisable apparatus used for characterizing the dynamic behaviour of various materials. Incident pulse generated one the incident bar usually have a rectangular shape, which is proper for some materials but for others is not. Therefore, several methods of shaping the incident pulse are used for obtaining constant strain rate conditions during tests. Very often pulse shapers made of copper or similar material are implemented due to its softness properties. In this paper such material was investigated using the FE model of SHPB. Its mechanical behaviour was characterised with and without copper disc between the striker and incident bar. Numerical simulations were carried out using explicit LS-DYNA code. Two different methods were used for modelling the copper sample: typical finite Lagrangian elements and meshless Smoothed Particle Hydrodynamics (SPH) method. As a result of two techniques used axial stress-strain characteristics were compared for three different striker’s velocity with an influence of the copper pulse shaper taking into account. Finally, FE and SPH method was compared with taking into consideration: the efficiency, computer memory and power requirements, complexity of methods and time of simulation

Abstract

The use of high resistance materials in nowadays structures has led to an increase in the span of the floors. Despite meeting the resistance and deformation criteria, floors might vibrate excessively due to increased slenderness. Based on a real-scale model experimental program, a parametric study has been developed in order to asses the vibration performance of prestressed hollow-core slab system on spans larger than the ones on which tests have been conducted, and the interaction between the concrete that have been poured in different stages. The measurements have been performed using Brüel and Kjӕr equipment, whereas the study has been carried out using Abaqus 6.11. finite element software. The simulations have been made by increasing the span of the slab, in order to observe the variation of the fundamental frequency. Also, the simulations have been conducted with different types of concrete topping thickness. The minimum acceptable value of the fundamental frequency has been considered 8Hz, according to existing literature.

Abstract

Introduction: The Achilles tendon is the most frequent recipient of traumatic injuries. The aim of this study is to identify and describe the varying load at ankle level and especially at the Achilles tendon’s insertion on the calcaneus.

Methods: We conducted a finite element analysis of the Achilles tendon while running, with the aim of revealing maximal loads and strains during a step in a running sequence. A 3D model of the Achilles tendon was built, based on MRI slides of a healthy, injury-free subject, who was asked to run over a force plate in 50 iterations. We used the recorded data to establish maximum loads and strains.

Results: We noticed a quick rise of the intra-tendinous load, from almost negligible while airborne and on first ground contact, to roughly 40 MPa in the pre-airborne phase, with possible implications in both treatment and post-injury recovery of Achilles tendon lesions.

Conclusions: Our results suggest that while early weight bearing and early exercise routines are a modern approach, care must be given in increasing the loads on the recovering region.

Abstract

Full flat slabs can be enhanced by using spherical voids to replace the unemployed concrete from the core part of the slab. Therefore we get low self-weighted slabs that can reach a high range of spans, a low material consumption compared to classical solutions used so far. On the other hand, the upsides of these slabs pale against the insecurity in design stage about their punching and shear force behaviour. In this paper it is presented a parametric study about shear force behaviour of flat slabs with spherical voids used in standard condition service. The study was made using the Atena 3D finit element design software, starting form a numerical model gauged on experimental results on real models – scale 1:1. Based on these lab results, the model’s validation was made by overlapping the load – displacement experimental curves on the curves yielded from numerical analyses. The results indicate that under a longitudinal reinforcement rate of lower than 0.50%, flat slabs with spherical voids don’t fail to shear force and over this value the capable shear force decreases in comparison with solid slabs, as the reinforcement rate increases.

Abstract

The stress distribution in specimens designed for the tensile testing is evaluated in the article. The reinforcement consists of long fibers that copy the outer contour of the specimen. The fibers are inserted within the curvature at the edge of the specimen with the neck. The stress distribution in fibers and matrix of dogbone specimen and specimen of rectangular shape is analyzed and compared. The analysis of stress state is analyzed in FEM software ADINA. Long fibers deposited in specimen were modeled using rebar elements.

Abstract

The main objective of the study is to develop experimentally validated FE model and perform numerical analysis of layered composites made by hand lay-up techniques during tension and bending test. The research object is glass - polyester laminate made of four unidirectional layers. In order to validate the numerical models experimental test were performed. Due to the very different stiffness modulus in tension and bending loading the material properties obtained from standard test are not suitable to apply in numerical model. Significantly different behaviour compared to experimental test was obtained for tree point bending where the numerical model becomes too stiff. Simple coupons, relatively easy to manufacture presented in the paper have very low quality. The differences in actual and theoretical bending stiffness (obtained from tension stiffness) exceed 70%. In order to represent the actual structure the layers of the composite were divided by resin layers and also additional resin layer at the top and bottom of the model were defined. Single stage optimization process was used to adjust the material layout. After layer set-up modification very significant improvement can be seen for flexural behaviour

Abstract

A three-dimensional finite element technique was used to analyse single pile lateral response subjected to pure lateral load. The main objective of this study is to assess the influence of the pile slenderness ratio on the lateral behaviour of single pile. The lateral single pile response in this assessment considered both lateral pile displacement and lateral soil resistance. As a result, modified p-y curves for lateral single pile response were improved when taking into account the influence lateral load magnitudes, pile cross sectional shape and flexural rigidity of the pile. The finite element method includes linear elastic, Mohr-Coulomb and 16-nodes interface models to represent the pile behaviour, soil performance and interface element, respectively. It can be concluded that the lateral pile deformation and lateral soil resistance because of the lateral load are always influenced by lateral load intensity and soil type as well as a pile slenderness ratio (L/D). The pile under an intermediate and large amount of loading (in case of cohesionless soil) has more resistance (low lateral displacement) than the pile embedded on the cohesion soil. In addition, it can be observed that the square-shaped pile is able to resist the load by about 30% more than the circular pile. On the other hand, pile in cohesionless soil was less affected by the change in EI compared with that in cohesive soil.

Abstract

One of the methods to increase the load carrying capacity of the reinforced concrete (RC) structure is its strengthening by using carbon fiber (CFRP) strips. There are two methods of strengthening using CFRP strips - passive method and active method. In the passive method a strip is applied to the concrete surface without initial strains, unlike in the active method a strip is initially pretensioned before its application. In the case of a steel-concrete composite beam, strips may be used to strengthen the concrete slab located in the tension zone (in the parts of beams with negative bending moments). The finite element model has been developed and validated by experimental tests to evaluate the strengthening efficiency of the composite girder with pretensioned CFRP strips applied to concrete slab in its tension zone.