Full-scale Static Tests Research Articles

Full-Scale Load Testing for Evaluating Crack Performance in Precast Prestressed Concrete Communication Towers with Annular Sections

Tall prestressed concrete poles with annular cross-sections are increasingly used as communication towers. The annular section subjected to bending moments has a smaller extreme tension area, resulting in higher stress increments in the materials within this region. As slender concrete structures, their bending behavior and crack resistance performance need to be critically examined. However, large-scale tower structures have rarely been experimentally investigated. Moreover, current code-specified crack width calculation methods are designed for square sections, so their applicability to concrete members with annular sections requires further investigation. To address these issues, this study conducted full-scale static loading tests on two 30-meter-high tower structures made of prestressed high-strength concrete and evaluated the accuracy of code methods for estimating the maximum crack width. During the static loading tests, displacement, cracking moments, crack widths, and crack spacings were meticulously recorded, and a theoretical methodology for calculating the stress in the extreme tension bars was developed. Four calculation methods specified in structural codes were compared: the Concrete Design Code of China (GB50010), Eurocode 2, ACI 224R, and the Concrete Design Guideline of Japan (JGC2007). The experimental results showed that diameter significantly affects the stiffness and displacement of the structure, with reloading stiffness of the full-scale tower reducing by up to 11% after exceeding the serviceability limit state. Regarding crack width prediction, substantial deviations were observed among the results of the four methods. On average, GB50010 underestimated crack widths, while JSCE, Eurocode 2, and ACI 224R overestimated them. Eurocode 2 and ACI 224R provided relatively conservative and accurate predictions. These findings highlight the need for improved and tailored code provisions for annular sections. It is also noted that the comparison was limited to crack widths less than 0.1 mm and a relatively small amount of data. Future research should focus on developing prediction methods specifically for prestressed concrete tower structures with annular sections.

BI-DIRECTIONAL STATIC LOAD TESTING

A full-scale static load testing program can optimise many of the requirements in terms of costs and remove uncertainties. The bi-directional load testing method, by eliminating the reaction structures of the traditional top-down testing methodology, opens up unseen possibilities of the testing program in the most efficient, safe, and cost-effective manner for all types of foundations, particularly for larger test loads. The benefits of using bi-directional load tests and how effective they are will be described in the paper. The revolutionary bi-directional static load testing method has also a significant side effect of reducing CO2 emissions for such tests by up to 80%.

Virtual Full Scale Static Test of a Civil Tilt Rotor Composite Wing in Non-Linear Regime

This study addresses the crucial role of post-buckling behavior analysis in the structural design of composite aeronautical structures. Traditional engineering practices tend to result in oversized composite components, increasing structural weight. EASA AMC 20-29’s Building Block Approach suggests phased testing, but its time and cost challenges necessitate a shift to high-fidelity post-buckling analyses, exemplified by MSC NASTRAN SOL 400. This approach, showcased in the analysis of the Next Generation Civil Tilt Rotor Technology Demonstrator’s wing (NGTCTR-TD), effectively de-risks static tests, contributing to a more efficient certification process. The study demonstrates how advanced simulations provide detailed insights into local buckling phenomena, allowing precise stress distribution analysis. These analyses eliminate the risk of structural failure, paving the way for safer, more efficient, and cost-effective airframe structures. Future developments aim to validate numerical analyses with experimental data, further emphasizing the reliability and benefits of high-fidelity simulations.

Confirmation of the operational reliability of building structures at the place of their installation in the building

The article presents the results of full-scale static tests of two reinforced concrete columns arranged in different parts of a public building, the reliability of which was doubted due to the careless manufacture of concrete cubes before sending them for laboratory tests. Based on the doubts that arose, the construction of the object under construction was suspended with the requirement of convincing proof of the operational reliability of these load-bearing structures.

Full-scale tests on the grouting effectiveness of offshore bored piles with various bearing strata

The bearing capacity of the post-grouted bored piles in sea-crossing bridges is greatly impacted by the kind of bearing stratum. Engineers are urgently concerned with the reinforcement effectiveness, improvement mechanism, and grout diffusion mechanism of tip-grouting of offshore bored piles in various bearing strata. Two groups of core-drilling inspections and six groups of full-scale static load tests were performed in this research. According to the test results, post-grouting significantly improved the load-settlement response of bored piles with various bearing strata. The improvement mechanism of tip-grouting included the formation of an enlarged pile tip, the pre-mobilization effect, and the improvement of bearing strata and soil–pile interface. The reinforcement effect of post-grouting in a coarse-grained soil bearing stratum was better than that of a fine-grained soil bearing stratum. The diffusion range of upward-flowing cement mortar in the coarse-grained soil bearing stratum and fine-grained soil bearing stratum was 14–15 m and 5–7.5 m respectively, and the diffusion range was significantly affected by the type of bearing stratum. The grout exhibited spherical penetration diffusion in the coarse-grained soil bearing stratum and splitting diffusion in the fine-grained soil bearing stratum, respectively. The investigation findings provided references for amending the existing construction method of post-grouted offshore bored piles in sea-crossing bridges.

Appropriate Strengthening Technologies for the Mitigation of Seismic Vulnerability of Bhutanese Vernacular Stone Masonry Architecture

ABSTRACT Bhutanese vernacular stone masonry architecture proved highly vulnerable to the recent seismic events affecting Bhutan since 2009. The isolation of rural communities, due to the site geomorphology, the precarious roads networks condition, the local labour limited skills, and the scarce resources availability, largely influence the applicability of strengthening technologies for traditional stone masonry architecture’s seismic vulnerability mitigation. Following up the collaboration with the Royal Government of Bhutan, within an international research project, the paper aims to analyse the appropriateness and suitability of strengthening intervention strategies to the local context. The identified strategies have been associated with the analysis of the stresses causing the failure mechanisms occurred during the 2009 earthquake and tailored to local construction technologies. A full-scale static test carried-out on a stone masonry-building mock-up, allowed to evaluate its behaviour under static loads. As a final result, the suitability of the interventions has been evaluated through qualitative indicators.

Artificial neural network response assessment of a single footing on soft soil reinforced by rigid inclusions

This study is devoted to investigate the behavior of a single footing resting on a soft soil reinforced by four rigid inclusions (RI) using an Artificial Neural Network (ANN). Full-scale static loading tests on a single footing are considered as the reference of this study. For the design of such structures, a geotechnical investigation allowed the soil properties determination. Then 3D Finite Difference Modeling (FDM) analyses were conducted and validated on the experimental results. A total of 196 datasets are used to construct and verify the Artificial Neural Network (ANN) response model accuracy. To follow the behavior of such footing, its center settlement, global load transfer efficiency and the maximum rigid inclusions bending moments are considered. This approach allows to efficiently assess the rigid-inclusion reinforced system performance with a high degree of success. Hence it is used to compute the RI-reinforced footing system responses under various configurations. A comparative study is carried out considering four key parameters of the load transfer platform. Four design charts are proposed and can serve for a pre-design stage.

Peculiarities of calculation and design of smooth orthotropic panels with considering geometric nonlinear behavior

When calculating the stability and bearing capacity of the panels of the caisson of the wing of an aerospace aircraft, it is necessary to take into account the presence of a heat-shielding coating, which also acts as an elastic base (EB) for the skin. The subject of this work is thin smooth orthotropic rectangular panels with an elastic base that does not perceive compressive and shear flows acting on the panel. The aim of the work is to develop methods for evaluating and designing composite panels associated with an elastic foundation, taking into account the possible geometrically nonlinear behavior under loads close to the design level. Note that the indicated level of loading can be realized only in full-scale static tests in the experimental justification of the strength of the wing structure. The paper presents analytical solutions of a geometrically nonlinear problem by the Bubnov-Galerkin method for rectangular orthotropic panels, taking into account the ER under the action of compressive and tangential forces. Based on the solutions obtained, methods for determining the thicknesses of orthotropic panels are proposed, taking into account two possible criteria: either reaching the ultimate strength stresses in a possible supercritical state, or reaching the limiting values of the deflection amplitude with geometrically nonlinear behavior. The last specified condition is a consequence of the requirements for the strength of the adhesive bond between the orthotropic skin and the heat-shielding layer. The paper considers smooth rectangular orthotropic panels with rigid support along the long sides and hinged support along the short sides.

Compensation of apparent strain data due to temperature gradients in a full-scale static test of a composite tidal turbine blade

Composite blades play a crucial role in a tidal turbine’s performance, and rigorous testing is required for certification before mass production. This study proposes a methodology for compensating strain measurements affected by temperature gradients using multivariate statistical regressions. This research utilises data analysis and signal processing techniques on strain and temperature datasets obtained from full-scale blade tests at FastBlade, the world???s first regenerative fatigue testing facility for tidal turbine blades. The multivariate regression model contains derived coefficients that separate temperature-induced strains from mechanical strains based on strain gauges coupled to their nearest thermocouples available. The linear model’s performance is assessed against static test datasets with different temperature conditions and scenarios. The proposed compensation method accurately isolated mechanical strains from high-temperature fluctuations from different sources acting on a large structure, enhancing the reliability of full-scale onshore tidal turbine blade testing.

Study on Mechanical Properties of Multi-Cavity Steel-Concrete Composite Beam.

This paper proposes a new form of composite beam: a multi-cavity steel-concrete composite beam. This composite beam uses internal perforated steel plate to connect the concrete with the steel structure, and shear connectors are no longer required, which is more suitable for industrial production. The mechanical properties of a multi-cavity steel-concrete composite beam in industrial applications are studied to avoid failures. In this paper, two multi-cavity steel-concrete composite beams with a size of 2500 mm × 200 mm × 300 mm were prepared, in which the angle of internal porous steel plate was set as 60° and 75°, respectively. A full-scale static load test was conducted on the beams to research its deformation and failure modes. The finite element software ANSYS was used to perform finite element modeling of multi-cavity steel-concrete composite beams and to analyze the influence of concrete strength, steel strength, porosity, and the angle of internal porous steel plate on the mechanical properties of composite beams. The results are as follows: before the composite beam reaches its serviceability limit state, its deformation basically shows a linear change; with the increase of load, the plastic deformation is gradually obvious, which can still provide a certain bearing capacity in the failure stage; the bearing capacity of the composite beam is positively correlated with the strength of concrete and steel, while negatively correlated with the porosity and the angle of internal porous steel plate; composite beams have large bearing capacity, good ductility and integrity.

Design and mechanical properties of U-section precast concrete box culverts

To study the joint design of U-section precast concrete box culverts (UPCBCs) and avoid the difficulty in obtaining the stiffness of joints, seven simplified two-dimensional models were proposed based on assumptions of joint constraints. Based on the comparison of internal forces, the cantilever model under axial compression was preliminarily selected to design a single-barrel UPCBC connected by unbonded prestressed bars. A full-scale static test was conducted and numerical model with seals was studied to verify the feasibility of the theoretical models. Furthermore, the effects of multiple factors (theoretical models and prestress) on the structural behaviors (failure modes, bearing capacity and deformation performance) were investigated based on a numerical model with distributed external loads. The evaluation index was analyzed to measure the comprehensive value of culverts, including the consideration of cost, the ability of theoretical models to predict the internal forces, the bearing capacity, and the deformation performance. Based on the results, the conditions of the sliding link model and unbonded prestressed bars (diameter of 12 mm and tensile controlling stress of 0.35 fpu) were recommended for the design of UPCBCs. Finally, the reliability of the design parameters were proved based on their application to a multi-barrel UPCBC. The results of this study provide a scientific reference for the structural design and applications of UPCBCs.

NUMERICAL ASSESSMENT OF CARRYING CAPACITY AND ANALYSIS OF PILOT BARETT BEHAVIOR IN GEOLOGICAL CONDITIONS OF VIETNAM

The article provides an analysis and comparison of the bearing capacity of barrett piles in difficult geological conditions at a construction site in Hanoi - Vietnam based on the results of analytical calculations using various methods. In particular, it contains calculation results according to Building Code of Russian Federation SP 24.13330.2011 "Pile foundations" [1], by numerical modeling of the pile operation under load using the PLAXIS 3D and MIDAS GTS NX software package, based on the results of field tests with piles (static load method). It is noted that the bearing capacity of bored piles and barret piles, according to the results of full-scale static tests with a limiting settlement of 40 mm, is in good agreement with the numerical solution (with the adopted soil model Hardening Soil (HS)) and with the calculation by the analytical method according to the strength characteristics of the soil base

Full-scale static and single impact testing of prestressed concrete sleepers reinforced with macro synthetic fibres

Excessive cracking of concrete sleepers has resulted in under-utilising its’ full capacity in the railway industry. By controlling such cracking behaviour of the sleepers, an optimised section can assist in minimising the maintenance budgets of the track authorities. Over the past decades, macro synthetic fibre reinforcement is gaining popularity as a structural fibre due to its improved tensile strength and elastic modulus. Characteristically, the implementation of fibre into concrete is well known for suppressing cracks and improving residual capacity. Thus, the work herein aimed at experimentally investigating the behaviour of macro synthetic fibre reinforced concrete sleepers under static and impact loading conditions. The capacity and failure modes at rail-seat are critically compared between sleepers with and without fibres, drawing the conclusions of higher ductility and higher energy absorption of prestressed concrete sleepers with fibre reinforcement.

Numerical simulation of interaction continuus fligt auger pile with a soil mass under static vertical load

The full-scale static test of a continuus fligt auger (CFA) pile for vertical loading by means of numerical modeling is reproduced.
 The modeling process can be divided into two stages: determining the calculated boundaries of the soil; identification of mechanical parameters of soils (young’s modulus (E), cohesion (c), friction angle (φ)).
 The first stage of modeling is to break the grid of finite elements in the plan so that it thickens from the periphery to the continuus fligt auger (CFA) pile (in our case, the pitch of the grid varies from 1 m to 10 cm). Then break the finite elements of the array in height with a certain step (in this work, a step of 1m). Then you need to determine how much the height of the soil will be under the pile tip. For this purpose 4 variants are considered: 2,5m; 5m; 10m; 20m. Looking at the results, it can be seen that starting from 10 m and less, deviations within 5%, so we take as a basis the soil thickness of 10 m. Then the size of the soil in the plan was selected. Five options were considered: 5x5m; 10x10m; 20x20m; 30x30m; 40x40m. The basis was 30x30m. As a result of this stage we take 10m under the pile, in the plan 30x30m (the pile is placed in the center).
 After establishing the dimensions of the calculation model, we are moving to the identification of the mechanical characteristics of the soil (E, c, φ). Identification of mechanical characteristics of the soil was performed in a layer around the pile 10 cm thick. At the beginning, the young’s modulus (E) was identified by linear calculation. It is established if the young’s modulus equal to 4E it allows to reproduce the results of field tests within the limits of elastic work of soil most precisely. If we take into account the nonlinearity, then our straight line begins to bend. Then, the cohesion (c) was identified, which showed that this indicator does not make a significant contribution to the relationship between load and sedimentation. Therefore, it is accepted to leave the cohesion unchanged. The friction angle (φ) is taken into account with a coefficient of 0.75φ.
 Based on the establishment of the size of soil mass and the identified mechanical parameters of the soil, the results of calculations were compared under three conditions strength: Huber-Mises, Drucker-Prager, Mohr-Coulomb.

OPTIMAL CONSTRUCTION AND TECHNOLOGICAL SOLUTION FOR RECONSTRUCTION OF A CITY PIPELINE AND THE RESULTS OF ITS TESTS

Purpose. To once again draw the attention of bridge owners and bridge experts to the problems of reconstruction of long-term bridges and on a concrete example of reconstruction of a rather problematic city overpass operated for more than 60 years to shows that with the optimal structural and technological solutions of the reconstruction received a restored bridge, and its operational and technical and economic indicators which according to the requirements of the National Building Norms completely correspond to the new bridge, but the reconstruction cost and the lead time are greatly reduced. Methodology. To achieve this purpose over the past ten years of operation of the overpass conducted three inspections and full-scale static tests. It is determined that most of the existing reinforced concrete structures, although defective and in need of repair, can be used for further operation after reconstruction, provided they are reinforced. Worn out non-repairable structures that needed to be replaced were also found. Results. According to these initial data, a reconstruction project was developed using scientific and technological structure developments of the Branch Research Laboratory 88 of Lviv Polytechnic National University for the reconstruction of bridges. The span structure has been expanded to 4 lanes from the size G-10.5 + 2 × 0.9 m to the new G-16.5 + 2 × 1.5 m in a combined way – symmetrical completion of two new beams with their support on the extended support and installation of a reinforced concrete extension board with cantilever overhangs 2.7 m long. The most damaged boundary beams were replaced with new ones, designed for normalized temporary loads A15 and NK-100. For further operation the other existing beams are reinforced in one of the least expensive ways – by changing the static scheme from the existing split to the new clamped on the supports frame-inseparable. A set of repair works is provided to ensure the normalized durability of the reconstructed overpass. The scientific novelty is to develop a method for determining the experimental Coefficients of Transverse Distribution of Bending Moments (CTDM) and external loads (CTD) based on the results of tests of the span structure. The possibility of applying the method of elastic supports for the spatial calculation of span structures with beams of different stiffness is confirmed. Practical significance. The use of optimal design solutions for the reconstruction of existing span structures: reinforced concrete billboard with large cantilever overhangs to expand and change the static scheme to strengthen the beams of span structures.

A Parametric Numerical Study for Diagnosing the Failure of Large Diameter Bored Piles Using Supervised Machine Learning Approach

The full-scale static pile loading test is without question the most reliable methodology for estimating the ultimate capacity of large diameter bored piles (LDBP). However, in most cases, the obtained load-settlement curves from LDBP loading tests tend to increase without reaching the failure point or an asymptote. Loading an LDBP until reaching apparent failure is seldom practical because of the significant amount of settlement usually required for the full shaft and base mobilizations. With that in mind, the supervised learning algorithm requires a huge labeled data set to train the machine properly, which makes it ideal for sensitivity analysis, forecasting, and predictions, among other unsupervised algorithms. However, providing such a huge dataset of LDBP loaded to failure tests might be very complicated. In this paper, a novel practice has been proposed to establish a labeled dataset needed to train supervised machine learning algorithms on accurately predicting the ultimate capacity of an LDBP. A comprehensive numerical parametric study was carried out to investigate the effect of both pile geometrical and soil geotechnical parameters on both the ultimate capacity and settlement of an LDBP. This study was based on field measurements of loaded to failure LDBP tests. Results of the 29 applied models were compared with the calibrated model results, and the variation in LDBP behavior due to change in any of the hyperparameters was discussed. Accordingly, three primary characteristics were identified to diagnose the failure of LDBPs. Those characteristics were utilized to establish a decision tree of a supervised machine learning algorithm that can be used to predict the ultimate capacity of an LDBP.

Installation of Bored Piles with a Protective Silicate Shell of a New Design in Saline Silty-Clayey Soils

Designing advanced methods of corrosion protection and increasing the bearing capacity of pile foundations on saline clayey soils is a priority geotechnical task in Kazakhstan. The formation of a suffusion-resistant waterproof shell was achieved by silicatization of a borehole before concreting, by the installation of a mold into the borehole and the impregnation of a sodium silicate solution into the space between the mold and the soil under pressure. After coagulation of the silicate solution, the mold was removed and the formed shell was filled with corrosion-resistant concrete. Full-scale static pile load tests were conducted in the construction site “Retaining wall on Mount Koktobe” in Almaty. The bearing capacity of the piles with the protective silicate shell exceeded the bearing capacity of an ordinary pile by 2.5 times on average without wetting the site, and 3.2 times after prolonged wetting. The numerical model had a close relationship with the average experimental curve obtained when conducting six static pile load tests with the protective shell. A large economic effect of the developed piling technology with a protective shell was achieved, with a significant reduction in the cost of piling, equal to 27.85%.

Full-scale static compression pile load test in sand with post installation pre-stressing to engage toe resistance

A full-scale static compression pile load test was conducted in connection with construction of a new road bridge in Silkeborg, Denmark. The new road bridge crosses a river between two existing bridges, one for pedestrians and one for an existing rail way. An existing pedestrian bridge was moved five meters to the north to give space for the new road bridge. The western part of the existing bridge was therefore to be founded partly on the existing footing of the pedestrian bridge and partly on a new pile-based footing. Bored cast-in-place piles were chosen to minimize vibrations during construction. The pile load test was necessary to document the bearing capacity of the bored piles because the Danish National Annex to the Eurocode 7, part 1 (2015), Annex L (DS/EN 1997-1 DK:NA) obligates the designer only to regard 30 % of the shaft resistance determined by geostatic calculation for the corresponding driven pile. Furthermore, it is a common design practise to disregard the toe resistance, as mobilization only occurs after deformations larger than normally acceptable for the superstructure. To overcome the latter, the test pile was constructed with a flat-jack device to allow post installation prestressing by grouting underneath the pile toe. Hence, it was possible to include toe resistance with only minimal displacements of the pile toe, as the grouting was conducted successfully, and post installation pre-stressing was obtained. The results of the pile load test show a bearing capacity up to 50% larger than estimated by geostatic calculation, even when including toe resistance and disregarding the 70 % shaft reduction in the geostatic calculation for the corresponding driven pile. An estimate of the displacement of the new pile-based footing was made based on load-displacement curves for the test pile, and the subsequent production piles were installed using the same principles due to the flat-jack device’s effective post installation pre-stressing.

A Study on Seismic Retrofit of Suspended Transportation Systems and Automated Storage Systems in A High-tech Fabrication Plant

<p>高科技廠房中懸吊式運輸系統（OHCV）與自動化倉儲系統（STK）為重要且不可於地震時停機之設施。2016年0206美濃地震中，某科技廠內該二系統因地震影響，設備物與產品嚴重損壞，致使系統無法短時間內修復完畢、恢復運轉，而損失大量金錢與產品。本研究目的為提升既有高科技廠房OHCV與STK之耐震能力，藉已驗證結構模型系統模擬地震下的模態與反應特性，並利用靜態側推與振動台實驗確認補強可行性，同時考量廠內現況、施工性、經濟性，分別提出經實驗驗證之有效補強系統。最後，補強電腦模擬皆顯示在設計地震下，系統反應確實較小。</p> <p> </p><p>The Overhead Conveyor (OHCV) and Stocker (STK) are most frequently used transportation and storage systems in high-tech factories and should not stop operation in an earthquake. However, these two systems are vulnerable to earthquake based on the Taiwan experience. In 2016 during Meinong Earthquake, damage of these two systems led to serious impact on high-tech factories. It not only shut down the production line, caused huge economical lose, but also delayed recovery process. This study aims to increase the seismic capacity of OHCV and STK for a high-tech factory. First, a rough numerical model to realize the true response under earthquake in the clean room was developed. By using full-scale static test and shaking table test, we can validate the dynamic characteristic of the numerical models. By considering the in-site situation, construction feasibility, and the economic demand, retrofitted bracing systems are developed. The strength of bracing is verified by component tests. Then, the efficiency for retrofitted OHCV and STK is verified by static tests and shaking table tests. Finally, the computed response in fab showed a drastically reduced response after the proposed retrofit.</p> <p> </p>

The Design of Static Test Scheme for Composite Aileron Structure of Large Aircraft

According to the load conditions and structural features of composite aileron structure of large aircraft, the design techniques of full-scale static test scheme of aileron is studied, which can be used to examine the static strength and verify the airworthiness compliance of aileron structure. The overall test scheme design was carried out from the aspects of test load, test support, damage introduction and measurement scheme, and created a set of test design processes that meet the requirements of airworthiness. Loads screening was carried out by using strain coverage principle, the aerodynamic loads were transformed into test load by coordinate transformation. The wing was used as the aileron test support section, and a ground support device can also be designed to carry out aileron bench test. The introduction mode of aileron structure damage was defined, including the type, location and size. A reasonable layout of strain and displacement sensors was given for test measurement. Test results showed that the static test scheme in this paper can be used for the airworthiness compliance verification of static strength of aileron structure.