Numerical Modelling of Tension Piles

in Beyond 200 in Computational Geotechnics (1999)

For determinations of the ultimate tension capacity of a piled foundation, often use is made of empirical relations between soil strength and skin friction. The disadvantage of these (analytical) methods ... [more ▼]

For determinations of the ultimate tension capacity of a piled foundation, often use is made of empirical relations between soil strength and skin friction. The disadvantage of these (analytical) methods is that they are in general not very accurate for most soil conditions. Therefore a numerical method for determination of the ultimate bearing capacity is presented here. Results were successively compared with actual test results which were measured during pile tests. It was found that the numerical model assessed the actual pile bearing capacity more closely than analytical models based on empirical calculation rules. Therefore lower factors of safety can be accepted. The behaviour of the (virtual) interface between pile and soil significantly influences the behaviourof the pile. [less ▲]

Numerical parametric study on minimum degree of shear connection in steel-concrete composite beams

Bachelor/master dissertation (2019)

In steel-concrete composite beams, the mechanical shear connectors are used to provide the shear transfer at the steel-concrete interface by connecting the concrete slab and the steel beam. Eurocode 4 (EN ... [more ▼]

In steel-concrete composite beams, the mechanical shear connectors are used to provide the shear transfer at the steel-concrete interface by connecting the concrete slab and the steel beam. Eurocode 4 (EN 1994-1-1), provides the design rules to achieve an adequate degree of shear connection. In recent years, revised rules have been proposed for the new generation of Eurocodes and research has been done to assess their suitability. The aim of this study is to complement previous studies and to evaluate the revised rules for minimum degree of shear connection of propped composite beams with ductile shear connectors and symmetric cross sections. First, a simple and comprehensive numerical model of a simply supported composite beam was developed in the finite element software ABAQUS and validated against previous numerical studies. Then, a parametric study was performed to evaluate the proposed rules on solid composite beams and composite beams with profiled steel sheeting for four span lengths (i.e. Lₑ= 6, 9, 12, and 15 m). For each span length, ten distinct configurations were analysed and each configuration was evaluated for five different degrees of shear connection (i.e. η= 0.20, 0.40, 0.60, 0.80, and 1.0). Thus, more than 200 simulations were completed in this parametric study. The results were post-processed and the suitability of the proposed rules was assessed in terms of end slip and midspan deflection at ULS and SLS respectively. The design rules led to adequate results in terms of midspan deflection. However, in some cases the end slip at ULS exceeded the 6 mm upper bound given in EN 1994-1-1 for ductile shear connectors. In order to properly identify and limit the end slip of the unsafe cases, the data from previous studies focusing on long span beams (i.e. 15m<Lₑ≤25m) was gathered with the results of the present study. Based on the assessment of the results, additional limitations to the revised rules were provided for the unsafe configurations. In these cases, the load level shall be limited by a reduction factor βₓ varying between 0.85 and 1, as a function of the plastic neutral axis depth to the overall height ratio (i.e. xₚₗ/h) and the composite to steel beam plastic bending resistance ratio (i.e. Mpl,Rd/Mpl,a,Rd). The effectiveness of this condition was re-evaluated and the results showed that more than 90% of the cases exhibited a maximum allowable end slip lower than 6 mm. Finally, a design proposal that accounts for the reduction factor βₓ was developed. [less ▲]

Numerical prediction of the rheological properties of fresh self-compacting concrete

Scientific Conference (2017, July 14)

Self-Compacting Concrete (SCC) is a high-performance construction material that can simplify classical handling on concrete construction by avoiding the need for additional vibrational compaction ... [more ▼]

Self-Compacting Concrete (SCC) is a high-performance construction material that can simplify classical handling on concrete construction by avoiding the need for additional vibrational compaction. Challenges in the use of SCC lie in ensuring optimal operation of the material in terms of properly filled castings in presence of complex reinforcement arrangements, reduction of entrained gas bubbles and limitation of aggregate separation. A major factor influencing the aforementioned aspects is the rheological properties of SCC mixtures under varying conditions (e.g. content composition, mechanical impact, temperature, moisture). This contribution aims at unified constitutive modelling of SCC in the setting stage. Concrete setting describes the transition from fluid-like fresh concrete, which -in presence of time- dependent transport-reaction processes- develops a porous cementitious structure, to hardened concrete showing solid-like behaviour. The constitutive model is implemented using the open-source finite element framework FENICS and applied to a number of benchmark problems. [less ▲]

A Numerical Scheme for Multisignal Weight Constrained Conditioned Portfolio Optimisation Problems

Scientific Conference (2014, December 17)

Numerical Simulation of a Diesel Particulate Filter during Loading and Regeneration

in ASME Internal Combustion Engine Division (2003)

Numerical simulation of energy harvesting devices driven by fluid-structure interaction

Scientific Conference (2015, June)

A specific class of piezo-electric energy harvesting devices for renewable energy resources is investigated. The key idea is to invert the traditional intention of engineers to avoid flow-induced ... [more ▼]

A specific class of piezo-electric energy harvesting devices for renewable energy resources is investigated. The key idea is to invert the traditional intention of engineers to avoid flow-induced excitation of structures such, that flow-induced vibrations can successfully be controlled and utilised in order to provide independent power supply to small-scale electrical devices. Possible application are e.g. micro electro-mechanical systems, monitoring sensors at remote locations or even in-vivo medical devices with the advantage of increased independence on local energy storage and reduced maintenance effort. This energy converter technology involves transient boundary-coupled fluid-structure interaction, volume-coupled piezo-electric-mechanics as well as a controlling electric circuit simultaneously. In order to understand the phenomenology and to increase robustness and performance of such devices, a mathematical and numerical model of the transient strongly-coupled non-linear multi-physics system is developed for systematic computational analyses. On basis of numerical investigations of the overall system optimal designs of the flow-induced vibrating piezo-electric energy harvester shall be identified with respect to electric power supply under varying exterior conditions. Vortex-induced excitations of a cantilever piezo-electric plate are exemplarily considered for studies on robustness and efficiency. [less ▲]

Numerical simulation of load flux and crack initiation in reinforced concrete columns with anchor plates and headed shear studs.

Scientific Conference (2006)

A typical constructional solution for the connection between steel and concrete load bearing elements in highrise- as well as multi-storey-buildings is the anchor plate in steel. A research project deals ... [more ▼]

A typical constructional solution for the connection between steel and concrete load bearing elements in highrise- as well as multi-storey-buildings is the anchor plate in steel. A research project deals with the numerical simulation of the load flux between anchor plate, headed shear studs and concrete. Most existing solutions in narrow constructions are dissatisfying in the point of using and analyzing the reinforcement effects. For crack propagation detailed concrete elements with 3d-nonlinear material properties are used. This includes tension and compression capabilities to simulate crack initiation and local failure behavior of the concrete. To cover structural nonlinearities the contact between steel and concrete is considered. The results in form of load flux and crack pattern are validated by comparisons to test results. The numerical simulation will help in optimizing the ratio and position of the reinforcement. [less ▲]

Numerical simulation of the motion and combustion of granular material.

in Industrial Heat Engineering (1999), 21

Numerical studies of magnetic particles concentration in biofluid (blood) under the influence of high gradient magnetic field in microchannel

Scientific Conference (2016, July 15)

Numerical study of magnetic particles concentration in biofluid (blood) under the influence of high gradient magnetic field in microchannel

Scientific Conference (2016, June)

A meshless numerical scheme [1] is developed in order to simulate the magnetically mediated separation of biological mixture used in lab-on-chip devices as solid carriers for capturing, transporting and ... [more ▼]

A meshless numerical scheme [1] is developed in order to simulate the magnetically mediated separation of biological mixture used in lab-on-chip devices as solid carriers for capturing, transporting and detecting biological magnetic labeled entities [2], as well as for drug delivering, magnetic hyperthermia treatment, magnetic resonance imaging, magnetofection, etc. A modified one-way particle-fluid coupling analysis is considered to model the interaction of the base fluid of the mixture with the distributed particles motion. In details, bulk flow influences particle motion (through a simplified Stokes drag relation), while it is strongly dependent on particle motion through (particle) concentration. Due to the imposed magnetic field stagnation regions are developed, leading to the accumulation of the magnetic labeled species and finally to their collection from the heterogeneous mixture. The role of (i) the intensity of magnetic field and its gradient, (ii) the position of magnetic field, (iii) the magnetic susceptibility of magnetic particles, (iv) the volume concentration of magnetic particles (nanoparticles) and their size, (v) the flow velocity in the magnetic- fluidic interactions and interplay between the magnetophoretic mass transfer and molecular diffusion are thoroughly investigated. Both Newtonian and non-Newtonian blood flow models are considered, along with different expressions for the concentration and numerical results are presented for a wide range of physical parameters (Hartmann number (Ha), Reynolds number (Re)). A comprehensive study investigates their impact on the biomagnetic separation. For verification purposes, the numerical results obtained by the proposed meshless scheme were compared with established numerical results from the literature, being in excellent agreement. [less ▲]