Full-scale Experimental Tests Research Articles

Comparative study of numerical modelling and experimental investigation for vessel-docking operations

A comparative study between numerical modelling and experimental investigation is performed to validate the developed numerical method for simulating floating dock operations with a vessel on board. Both model-scale and full-scale experimental tests are performed on floating docks with a vessel on board, and the draughts using draught meters, floating positions and bending of the floating dock are measured. The present numerical method is proposed based on a quasi-static assumption during vessel-docking operations. A static analysis model is built to determine the static response of a floating dock under a specific ballast water distribution based on a hydrostatic force model and a Newton-Raphson method. A bending model is proposed to calculate the deflection of the floating dock along the longitudinal direction. Results of the mode-scale tests show that the draught measurements and the floating positions of the dock and vessel predicted using the present numerical method agree well with the corresponding experimental results. It proves the accuracy of the present numerical method for simulating vessel-docking operations. Moreover, a well-designed ballast plan enables successful de-ballasting operations on the model-scale dock, even in the event of one to three pump failures. The comparison of the deflection changes of the floating dock in the field test measurements further proves the accuracy of the present bending model. Therefore, the validated numerical model tested on both model-scale and full-scale docks provides a reliable foundation for creating digital twin of floating docks in shipyards.

Wave propagation analysis of the overhead conductor rail system based on numerical simulation and full-scale experiment

The overhead conductor rail system (OCR) is an important current-transmitting structure for electric trains in tunnels. As the train speed increases, the wave propagation behaviour in the OCR plays an ever-increasingly important role in affecting the current collection quality. This paper is the first endeavour to numerically and experimentally explore wave behaviours in the OCR. With the help of a finite element model, the spatial propagation and frequency-domain characteristics of the wave propagation are investigated. Based on the time-space distribution of waves, the wave speed of the OCR is identified. Subsequently, a full-scale experimental test is conducted to identify a real-life OCR's wave speed for the first time. The relative error between the simulated and experimental speed is only 5.50 %, highlighting the effectiveness of the presented model. Then, the influence of wave propagation on the interaction performance of pantograph-OCR is analysed. A significant reduction of the interaction performance is observed when the train speed approaches the wave speed. Through sensitivity analysis, the bending stiffness, the linear density, and the span length are identified as sensitive parameters affecting the wave speed.

Structural integrity of aging steel bridges by 3D laser scanning and convolutional neural networks

For steel bridges, corrosion has historically led to bridge failures, resulting in fatalities and injuries. To enhance public safety and prevent such incidents, authorities mandate in-situ evaluation and reporting of corroded members. The current inspection and evaluation protocol is characterized by intense labor, traffic delays, and poor capacity predictions. Here we combine full-scale experimental testing of a decommissioned girder, 3D laser scanning, and convolutional neural networks (CNNs) to introduce a continuous inspection and evaluation framework. Classification and regression CNNs are trained on a databank of 1,421 naturally inspired corrosion scenarios, generated computationally based on point clouds of three corroded girders collected in lab conditions. Results indicate low errors of up to 2.0% and 3.3%, respectively. The methodology is validated on eight real corroded ends and implemented for the evaluation of an in-service bridge. This framework promises significant advancements in assessing aging bridge infrastructure with higher accuracy and efficiency compared to analytical or semi-analytical approaches.

Investigation of the performance of a newly designed solar chimney for enhancing natural ventilation and mitigation of summer overheating

The significant challenge encountered in utilizing Trombe walls for winter heating is summer overheating, which limits the overall feasibility of the system. In response to this issue, the present study introduces a novel model of a Trombe wall-solar chimney system designed to enhance natural ventilation and address the problem of summer overheating. To assess the performance of the proposed model, a full-scale experimental test rig is constructed in Kirkuk, Iraq. This rig comprises a test room integrated with a Trombe wall-solar chimney system. Additionally, a numerical simulation based on the CFD approach along with a computer code is developed to investigate the behavior of the system. System analysis is conducted for the period August 14th–15th. The parameters studied include chimney height (ranging from 0.0m to 2.0m in 0.5m increments), chimney width (0.2m, 0.3m, 0.4m, and 0.5m), room inlet vent height (ranging from 0.2m to 0.4m with 0.05m increments), and chimney inlet vent height (ranging from 0.2m to 0.4m with 0.05m increments). The results highlight the crucial role of the massive storage wall in sustaining nighttime ventilation in the absence of solar energy by utilizing stored heat to warm the air and maintain the ventilation process. The study establishes that chimney height and width significantly influence airflow rate, while other factors have marginal effects. An empirical equation is formulated to predict the 24-h averaged air changes per hour (ACH), which is a critical measure of system performance in ventilation. This equation is developed using artificial neural network (ANN) techniques. Finally, the findings indicate that the suggested model effectively reduces summertime overheating while generating a satisfactory ventilation rate. This enhances the overall versatility and year-round usability of Trombe wall systems, making them more adaptive and efficient in regions with diverse climatic conditions.

Development of a Novel Dynamic Wellbore Fracturing Technology by Integrating Full-Scale Experimental Testing and FDEM Numerical Simulations

Development of a Novel Dynamic Wellbore Fracturing Technology by Integrating Full-Scale Experimental Testing and FDEM Numerical Simulations

Numerical investigation on the behaviour of concrete barriers subjected to vehicle impacts using modified K&C material model

Full-scale experimental crash tests are important to determine the occupant risk factors and understand barrier system behaviour in vehicle-barrier impacts. Due to the expensive and time-consuming nature of such crash tests, finite element simulations of full-scale crash tests to analyse and design road safety structures have gained popularity as a more practical method of assessment. In this research, a simplified simulation technique was employed by dividing the barrier system into two sections called the Impact Zone and the Rigid Zone, which was adopted for concrete crash barriers for the first time. A previously performed experimental crash test was used to successfully validate the numerical model. The numerical crash model accurately predicted the critical parameters of the barrier performance. The numerical simulation was further used to extract otherwise difficult or impossible results from the experimental crash test, such as internal energies and exit angles. The importance of the use of optimised Karagozian and Case concrete material parameters was demonstrated through a parametric study carried out with autogenerated parameters. A parametric study performed with impact speed and angle proved that increased speed is more harmful for occupants than a more oblique impact angle. The potential benefits of replacing traditional concrete with improved energy absorbing concrete to reduce occupant risks were also investigated. The comparison of results between the numerical models and experimental crash test confirms the trustworthiness of the developed models to simulate the vehicle-barrier crashes for analysing existing barrier designs and further developing new barrier designs to increase road safety.

Experimental Study on Flexural Resistance of UHPC Wet Joint Precast Reinforced Concrete Bridge Deck Slabs with Variable Cross-Section

With the convenient and fast requirements for construction in bridge engineering, prefabricated assembly technology is widely applied in engineering construction. Typically, prefabricated bridge decks are connected through cast-in-place wet joints. Wet joints, as the primary load-bearing parts of bridge decks, undergo complex stress and are prone to cracking and damage. Particularly in the negative bending moment region of bridges, the influence of tensile stress on wet joints is more severe, thus enhancing the mechanical performance and crack resistance of joints becomes crucial. This paper investigates the mechanical behavior of prefabricated reinforced concrete bridge deck panels with variable cross-sections under negative bending moments, focusing on the performance of Ultra High-Performance Concrete (UHPC) wet joints. Full-scale experimental tests were conducted on a 176 m steel truss composite continuous rigid bridge, employing C50 concrete panels with UHPC wet joints. Results show three distinct stages: elastic, crack initiation and propagation, and failure. The maximum failure load reached 822 kN, with a maximum displacement of 21.64 mm. Concrete strains indicate compressive stress near the wet joint and tensile stress near the loading positions. Cracks primarily develop at the wet joint interface and propagate under increasing load, ultimately leading to flexural–shear failure near the variable cross-section of the wet joint. Numerical simulations using ABAQUS/CAE (2020) corroborate experimental findings, closely matching load-displacement curves and identifying damage locations. The study demonstrates that UHPC wet joints significantly enhance crack resistance, meeting design requirements for improved mechanical performance in bridge structures subjected to negative bending moments.

Space-Time Pressure Distribution Applied to a Stiff Concrete Structure through a Protective Sand Layer from Full-Scale Experimental Rockfall Tests

Space-Time Pressure Distribution Applied to a Stiff Concrete Structure through a Protective Sand Layer from Full-Scale Experimental Rockfall Tests

Shear Test of Corrugated Web Girders with Concrete-Filled Compression Tubular Flanges Used in Buildings

Corrugated web girders with plate flanges have been widely applied in buildings and bridges due to the large shear capacity of the corrugated web (CW). However, experiments on corrugated web girders with tubular flanges are limited. Accordingly, this paper explores, through four full-scale small-size experimental tests used on buildings, the shear behavior of a type of girder formed with a CW, concrete-filled tubular flange, and bottom flat plate flange (CWGCFTF) with different CW thicknesses, wavelengths, and concrete strengths. Based on the imprecise results of one current test, a novel simple support device is proposed to improve the accuracy of the shear test of the CWGCFTF. The test results also show that the shear ratios of the tubular flange to the entire cross-section range from 15–18% when the loading reaches that of the corresponding shear stress to 80% of the shear yield strength of the CWs. Moreover, local buckling appears at the top surface of the steel tube with the CW shear buckling failure of the CWGCFTF under the shear tests. At the end, a theoretical equation of the shear ratio of the CW to the whole cross-section is derived, and a shear yield strength equation of the CWGCFTF is proposed and verified by comparisons with the test results.

Numerical and semi-empirical models for the stress analysis of flexible pipes tensile armors terminations within end-fittings

The tensile armors of flexible pipes are typically terminated in two configurations, i.e., hook and pigtail, essential to guarantee the tensile armors’ anchorage in the pipe's end-fitting. However, despite its importance for the secure operation of flexible pipes, few works have dealt with the mechanical analysis of these terminations. Hence, this work proposes numerical and semi-empirical models to study the stresses induced on them by operational and extreme loading. Two- and three-dimensional finite element (FE) models are initially proposed, and their advantages and limitations in estimating local stiffness, stresses, and associated failure modes are highlighted. The initial analyses indicated that the two-dimensional model underestimated the terminations’ stiffness, while the detailed three-dimensional model required significant computational effort. However, a simplified three-dimensional model achieved the best compromise between accuracy and computational effort. In common, all models indicated that the hook termination failure is due to a pullout mechanism, while the pigtail induces the tensile armor steel rupture. After that, the simplified three-dimensional model was employed to conduct a parametric study involving several physical and geometric characteristics of the terminations. The importance of these parameters was evaluated using the Design of Experiment (DoE) technique, leading to semi-empirical equations to predict the maximum stresses induced in the terminations due to an axial load imposed on the tensile armor. Finally, the semi-empirical equation obtained for the hook termination was verified using previously presented full-scale experimental test results, showing good agreement.

Rotor resonance avoidance by continuous adjustment of support stiffness

This paper presents a method to reduce lateral vibration amplitudes in large rotating machines. The method is based on avoiding resonances by altering the natural frequencies of the rotor system at each rotating speed during operation. While many research papers have considered altering support stiffness during crossing critical speeds, continuous adjustment methods have received less attention. Continuous on-line adjustment of the natural frequencies of a rotor system is possible to a large range by adjusting the support stiffness of the bearing housings. The optimal foundation stiffness tuning policy can be defined utilizing a rotordynamic model or experimental measurements, effectively creating a resonance-free operating speed region, where vibrations are drastically reduced. It is shown through full-scale experimental laboratory tests, that the subcritical and supercritical response of the rotor system is significantly decreased during run-up and run-down with the optimal foundation stiffness tuning strategy. The developed method can be applied to reduce vibrations in any rotating machinery, where a variable foundation stiffness control can be installed. Moreover, this on-line foundation stiffness tuning strategy could also be applied in combination with resonance crossing methods involving stiffness manipulation.

Adaptive building envelope combining variable transparency shape-stabilized PCM and reflective film: Parameter and energy performance optimization in different climate conditions

Developing an adaptive building envelope (ABE) to cope with drastic changes in the ambient environment contributes to achieving the goal of net-zero emissions by 2050 in the building industry. In this study, two types of ABE, namely, adaptive ventilation and sunlight regulation wall (AVSRW) and adaptive sunlight regulation wall (ASRW), were designed by combining variable transparency shape-stabilized PCM (VTSS-PCM) and reflective film, and the AVSRW had an air cavity to control the heat storage and release of VTSS-PCM. The numerical models of the two ABEs and the massive wall (MW) were developed and validated by a full-scale experimental test. Based on these validated numerical models and weather datasets in four climate zones of China, the energy performances of AVSRW were simulated under the influence of melting temperature (Tm) of VTSS-PCM, thickness (L) of VTSS-PCM, and reflectivity (R) of reflective film. Then, a bi-objective global optimization was conducted to find the optimal performance and design parameters of AVSRW. Finally, the AVSRW and the ASRW with the optimal design parameters were compared with and the MW. The parameters analysis revealed that the combined action of Tm, L, and R on AVSRW determined the trade-off among the heat conducted to the interior, the solar energy stored by VTSS-PCM, and the solar energy reflected by the reflective film. The optimization results showed that, in the climate conditions of Beijing, Changsha, Guangzhou, and Harbin, the optimal values of Tm were 24.02 ℃, 24.37 ℃, 25.86 ℃, and 23.43 ℃, respectively; the optimal values of L were 0.16 m, 0.16 m, 0.09 m, and 0.16 m, respectively; the optimal values of R were 0.23, 0.29, 0.79, and 0.33, respectively. Under the optimal values of Tm, L, and R, compared with MW, the annual ESRs of AVSRW and ASRW were 84.26 % and 38.71 % in Beijing, 81.98 % and 39.45 % in Shanghai, 70.28 % and 55.53 % in Guangzhou, 76.20 % and 29.54 % in Harbin. This study provides the basis for the design and optimization of AVSRW and ASRW in different climate regions.

Development of compliant modular floating photovoltaic farm for coastal conditions

Floating photovoltaic (PV) farms can be constructed in coastal marine conditions for the abundant ocean space compared to reservoirs. New challenges may arise when extending existing designs of reservoir floating PV farms to coastal regions because of the complex environmental conditions, especially for the pontoon type floating PV systems. This study presents the methodologies for the design and verification of such floating PV farms based on the practical example of one of the world's largest nearshore floating photovoltaic farms off Woodlands in Singapore. This 5 MW pilot project aims to move floating PV farms from inland water to nearshore regions for future larger-scale deployments. The innovative floating system is adapted from the successful modular floating PV development at Tengeh Reservoir and improved to withstand harsher marine environmental conditions. This study comprehensively introduces various aspects of the development of the nearshore floating modular PV farm, including its design, verification via full-scale experimental testing and numerical studies, construction, and power generation performances. The floating PV system comprises standardized floating modules made of high-density polyethylene (HDPE) that support PV panels or operational and maintenance work. A compliant design allows the floating system to follow wave motion. A verification study was conducted through full-scale experimental tests and numerical simulations based on a representative subsystem of the floating PV farm, focusing on its hydrodynamic performance. Finally, this study presents and discuss the on-site operational energy production performance. This study may serve as a reference for developing large-scale floating PV farms in coastal marine conditions.

Experimental evaluation of airflow guiding components for wind-driven single-sided natural ventilation: A comparative study in a test chamber

Single-sided ventilation is a frequently employed ventilation strategy in contemporary structures, yet its effectiveness is often mediocre, underscoring the need for solutions to enhance its performance. To evaluate the effect of louvres and guide vanes on the effective ventilation rate, 21 different louvre configurations and four guide vane designs were compared with a plain opening for single-sided ventilation in a full-scale experimental test chamber under three different magnitudes of local wind velocity. Ventilation rates were measured using the tracer gas decay method with 12 NDIR CO2 sensors. The findings, obtained under specific test conditions, indicate that deeper openings result in a decline in ventilation rate performance. It was observed that wider guide vanes lead to higher ventilation rates, suggesting their potential to enhance SSV performance. The results reveal that, in most cases, louvres contribute to a decline in the system's performance. However, the ventilation rate is influenced by the angle and number of louvres, with optimal performance observed at specific angles and fewer louvres. These findings provide valuable insights for optimizing the design of airflow-guiding components in wind-driven single-sided ventilation systems, enabling the development of more efficient and customized solutions for natural ventilation in buildings.

Influence of structural irregularity on the q-behaviour factor of light-frame timber buildings by means of incremental dynamic analysis

This paper investigates the role of sheathing-to-framing connection ductility in the evaluation of the structural q-behaviour factor for Light-Frame Timber (LFT) buildings, by means of Incremental Dynamic Analyses (IDA). This approach allows to consider nonlinear cyclic behaviour of the walls, which cannot be taken into account with the static approaches used in most of the available literature on LFT buildings. To this aim, Finite Element wall models, preliminary calibrated towards a cyclic full-scale experimental test, are built to study six case-study buildings, both regular and non-regular, with 2, 3 or 4 storeys, which were designed according to Eurocode and Capacity Design provisions. Parametric analyses are performed by varying the displacement-ductility of the panel. Finally, numerical results are discussed in terms of q-behaviour factor, and its sensitivity to structural irregularities, with respect to existing code provisions for timber buildings.

Full-scale analysis of smart fluid-filled barrier technology: Numerical and experimental study of fixture configurations

Roadside barriers are often deployed to prevent vehicles from colliding with roadside obstacles or hazards and from leaving the road surface. These barriers primarily take the form of guardrails or crash cushions and are designed to absorb energy through severe plastic deformation. Due to the severity of these types of collisions, the energy-absorbing mechanisms can fail resulting in the barrier becoming a hazard. To address this issue, a (US Patented) multi-chambered, smart fluid-filled barrier technology (SFFBT) was proposed as a potential replacement for such roadside barriers. This new patented technology utilizes fluid transport between the internal chambers and viscous dissipation as an additional energy-absorbing mechanism to help reduce the effects the severe deformation imparts on the colliding vehicle and its occupants. Numerical models were developed in ABAQUS dynamic explicit environment, and full-scale experimental testing was conducted at the Midwest Roadside Safety Facility of the University of Nebraska—Lincoln. Three barrier configurations were considered for this study with two different fluid levels resulting in six unique test samples. The three test configurations were (a) free-standing, (b) abutted against a rigid backstop, and (c) anchored. Fluid levels chosen were 25% and 33% filled volume. The results show that the proposed designs and fluid addition provided an increase in energy absorption while decreasing overall deformation stroke by up to 5%. Additionally, kinetic energy reduction increased by 15% with a nearly 140% increase in fluid energy dissipation. The best-performing configurations were the rigid backstop cases, followed by anchored and free-standing configurations. The effects of varying anchoring schemes provide additional performance evaluations for maximizing the energy-absorbing performance of the SFFBT system for use as an impact attenuator.

Analysis of tapered three-layered sandwich flexural members (Stobie poles) with partial shear interaction: Analytical model

This research paper presents an analytical model for predicting the load–deflection curves of three-layered sandwich (TLS) beams with interlayer slips, accounting for material nonlinearity in all three layers. An advanced 1D beam element with five degrees of freedom per node was developed to simulate the structural behaviour of TLS beams, with two additional degrees of freedom for slippage between adjacent layers. The Euler–Bernoulli kinematic assumptions were adopted, and the governing equations were derived based on equilibrium equations, followed by the derivation of the weak form equations. The finite element formulation was then developed, and the Newton–Raphson scheme was adopted for the solution of the nonlinear system of equations, with five-point Gaussian quadrature used for the integration over the length of the beam and trapezoidal integration used for the integration over the area of the cross section. The proposed model was applied to tapered steel-concrete-steel sandwich flexural elements known as Stobie poles. The model results were verified with full-scale experimental tests and numerical models, and the effects of slippage constitutive relationship, cross-section tapering, and mechanical properties of the core and skin layers were evaluated. The presented model provides a reliable tool for designing and analysing three-layered sandwich beams with partial shear interaction.

Full scale experimental tests to evaluate the train slipstream in tunnels

The train slipstream, i.e. the air velocity induced by the train, is one of the most important aerodynamic effects connected to railway vehicles because it has a direct impact on the safety of passengers on the platform and track workers along the railway line. In recent years, a lot of studies were performed to understand the development of this phenomenon in open field, and specific EU standards, the EN 14067–4 and the TSI were issued. Instead, only few studies have been carried out to analyse the train slipstream in confined spaces (as tunnels, line sections with acoustic barriers, etc.), even though the first results of these analyses have shown that the confinement of the air causes more severe conditions regarding the speed of the air flow. This work aims at studying, through a full-scale experimental campaign, the effects on the air flow speed caused by the train passage. The effects of different train parameters (i.e. train type and length, etc.) and infrastructure parameters (i.e. geometry variations) were analysed. Lastly, the results of a specific test considering the presence of a stationary train inside the tunnel while another train is passing are described, to simulate scenarios of ordinary railway traffic.

Fire Resistance of Fire-Protected Reinforced Concrete Beams Strengthened with Externally Bonded Reinforcement Carbon Fibre-Reinforced Polymers at the Full Utilisation Degree.

The fire resistance of reinforced concrete (RC) beams strengthened with externally bonded reinforcement carbon fibre-reinforced polymers (EBR CFRP) depends on the load level and degree of strengthening. Design guides for this type of structure recommend strengthening limits to prevent collapse of the structure due to vandalism, damage or fire. In practice, however, it is not uncommon to exceed the proposed limits. This necessitates protection of the CFRP adhesive against high temperatures, namely glass transition temperature levels. This paper presents the results of 10 full-scale experimental fire resistance tests of reinforced concrete beams with EBR CFRP strengthening, with and without fire protection and under various load levels including full utilisation. It was demonstrated that in cases where CFRP strengthening was not needed to carry load in an accidental fire scenario, test specimens with and without it achieved the same fire resistance. It was also proven that in cases where CFRP failure influenced the failure of the entire beam, fire protection was crucial for maintaining the beam's load-bearing capacity and its thickness had to be substantial. A fire resistance rating of over 4 h was achieved, nevertheless.

Full-Scale Testing and Analytical Modeling of Rebar Cages Reinforced with Mechanical U-Bolt Connectors

Rebar cages are the skeletons of reinforced concrete structures. These temporary structures consist of longitudinal and transverse reinforcing bars connected by tie-wires. Given the relatively low strength of tie-wire connections, replacing tie-wires with mechanical connectors such as U-bolts can improve the stability and strength of rebar cages. This paper aims to understand the behavior of large prefabricated rebar cages reinforced with mechanical U-bolt connectors through experimental and analytical investigations. Twenty-six full-scale experimental tests are performed on five different underground pile-shaft rebar cages with tie-wire and U-bolt connectors to determine their behavior during different site handling conditions. The data obtained from the experiments are used to develop and calibrate detailed finite element models that can predict the complex response behavior of rebar cages reinforced with U-bolt connectors. The results show that U-bolt connectors can effectively ensure rebar cage integrity even under extreme loading conditions. Additionally, it is concluded that the presence of U-bolt connectors allows for the elimination of internal stiffening elements, which are common for large rebar cages, adding to the simplicity and efficiency of the construction process. The results of this study can be used as a basis for establishing analysis, design, fabrication, and handling guidelines for rebar cages.