Large-scale Test Setup Research Articles

Validated Finite-Element Model for Predicting Asphalt Concrete Overlay Reflective Cracking Potential

The reflective cracking potential of overlay systems is often studied through large-scale testing, which is time-consuming and expensive. Therefore, a generalized 3D finite-element model was developed to simulate a large-scale test setup to predict the reflective cracking potential. Crack propagation was modeled, and fracture parameters, such as stress intensity factor (SIF) and J-integral, were obtained. Mode I cracking dominated the model’s crack propagation, while in-plane shear cracking was insignificant. The model was validated with large-scale testing results; the average Mode I SIF was found to be a valid measure to assess the overlays’ reflective cracking potential. The model could be used qualitatively to compare different overlay configurations. A database of 128 cases was generated to compute fracture parameters for extreme scenarios or a combination of inputs. A data-driven surrogate model that predicts reflective cracking potential was developed to allow easy application by agencies. Shapley Additive Explanations (SHAP) analysis confirmed the model’s robustness. The surrogate model may be used by engineers to select asphalt concrete mixtures and design overlay thicknesses to control reflective cracking potential.

Experimental Study of Axially Loaded Pile Group Near a Sloping Ground

Understanding the axial loading response of pile group located near the crest of the slope is of practical value to structural design. In this paper, a large-scale test setup (1.8 m × 0.90 m × 0.90 m) has been developed to investigate the response of pile group (2 × 2) located near the crest of the slope under axial loading. This paper presents a series of physical modelling tests performed to investigate the effects of slope angles, distance of the pile group from the slope crest, embedment length of the pile group and pile diameter on the axial loading response of pile groups. The results show that the response of pile group located near the crest of the slope approaches to the level ground condition with increasing edge distance from slope crest. In addition, the horizontal displacement of pile group towards the slope face increases with decreasing distance of pile group from the slope crest or embedded length of piles or with increasing slope angle. Furthermore, increasing pile diameter results in a low increase in the horizontal displacement for edge distances less than 3 dp (dp = pile diameter). However, the horizontal displacement is almost independent of pile diameter at edge distances greater than 3 dp. Higher embedded length results in the response of pile group approaches to the response of pile group located on the level ground at a shorter edge distance from the slope crest.

Rockburst simulation using dynamic tests on the support system

Ground support for dynamic conditions must be able to withstand the associated loads and deformations and the support scheme must work as a system. In order to prove the suitability of such support systems with high-tensile steel mesh and bolts and to analyze the bearing behavior of them, a large-scale test setup was commissioned in Walenstadt, Switzerland. On this test rig it is possible to apply large energies on variable ground support systems with variable bolt patterns and meshes with a total support area of 3.6 × 3.6m in a full-scale way. The test site is instrumented by load cells, high-speed video analysis and accelerometers. In this paper the analysis of the load cells, the accelerometers and the high-speed video cameras is given, and results of system tests are discussed.

Experimental investigation of axially loaded group of piles with and without building frame: a parametric study

In the design of structures, stability and safety play a crucial role in serviceability. The response of the soil which influences the motion of the structure and vice versa is termed soil–structure interaction (SSI). Interaction effect is ignored to simplify the mathematical model for the analysis of problems involving soil interaction. In reality, the actual behaviour of the substructure is altered significantly if one considers the interaction among the foundations and the soil medium. In this study, a large-scale test setup (1.4 m × 0.8 m × 1.0 m) has been developed and model pile has been designed to find out the influence of SSI. Experimental tests were conducted on single pile, pile group (2 × 2), and pile-group-supported building frame subjected to an axial load. Parametric studies were conducted by varying pile spacing (3D, 4D, and 5D), aspect ratio (15, 25 and 40), and relative density of sand bed (35% and 70%). Pile cap rotation, pile head deflection, and bending moment values were measured for various configurations. The results showed that experimental findings are more useful for the evaluation of soil–structure interaction, and there is a necessity to consider the interaction effects in the calculation of design forces.

A large-scale test set-up for measuring VOC emissions from wood products under laboratory conditions in simulated real rooms

Abstract A large-scale test set-up was designed to evaluate the volatile organic compound (VOC) emissions of building materials in a real room situation but under laboratory conditions. Two model rooms (ModR) with a volume of 30 m3 each were constructed of the wood-based building materials X-lam and OSB, respectively. Temperature and relative humidity (RH) inside the ModR were kept in a range of 21°C–25°C and 45%–55% RH. VOCs were collected at 13 different times over a period of 23 weeks, and the total VOC (TVOC) concentration was calculated from GC/MS data. Results were quantified as toluene equivalents (TE). In the X-lam-ModR, the TVOC concentration decreased by 64% over the whole measurement period from 115 to 41 μg m-3 TE. Terpenes were the most abundant substance group and accounted, on average, for 80% of the TVOC concentration. In the OSB-ModR, the TVOC concentration decreased by 72% from 443 to 124 μg m-3 TE. Aldehydes showed the highest concentrations, accounting, on average, for 52% of the TVOC, while 38% were terpenes. The results show that this type of test provides realistic data for the praxis.

Experimental investigation of the load–displacement behaviour under catenary action in a restrained reinforced concrete slab strip

When a support of a statically indeterminate concrete slab is lost due to an accidental event, tensile membrane or catenary forces can be activated at large deflections. This effect can considerably increase the load-carrying capacity compared to predictions obtained from small deformation theories neglecting membrane and catenary forces. Thus, these actions can prevent a progressive collapse and hence increase the robustness of concrete structures. A novel experimental large-scale test set-up is described which allows the testing of continuous, longitudinally restrained, reinforced concrete slab strips exposed to a simulated accidental failure of the central support and subsequent vertical loading until collapse. The details of this test set-up as well as the measurements related to the load–displacement behaviour are explained. Within this investigation the development of catenary action associated with the formation of large displacements was found to increase the ultimate bearing capacity significantly.

The influence of Anisotropic Stiffness on the Consolidation of Peat

An analytical solution for the consolidation problem of an axially loaded triaxial sample including anisotropy in stiffness is presented. The solution shows that anisotropy in stiffness strongly influences the consolidation process. The influence of anisotropy in stiffness is found in the initial pore pressure reaction, in the Mandel-Cryer effect and in the consolidation coefficient. Measurements on conventional sized peat samples appear not to correspond to the analytical solution. Besides drain resistance, literature presents two other explanations for this fact. These explanations are tested in a large scale test set-up. It is found that induced permeability changes have a strong influence. The possibility of using the Mandel-Cryer effect for assessment of stiffness parameters of peat introduces extra parameters to describe the variations in permeability. For strongly over-consolidated samples, leading to a nearly constant permeability the analytical solution fits perfectly to measurements.

The alignment system of the ATLAS muon spectrometer

The muon spectrometer of the ATLAS detector at the LHC has been designed to provide a good stand-alone momentum resolution for muons up to about 1 TeV. For this purpose, muon drift tube chambers with very high spatial resolution were developed; in addition, a precise online alignment monitoring system is required. This system is based on optical sensors measuring the individual deformations and the relative positions of muon chambers; temperature sensors are used to monitor their thermal expansion. In the endcap, the alignment system has to make use of additional alignment bars, used as precision reference rulers. In the year 2002, the ATLAS muon collaboration has installed a large-scale test setup of the muon spectrometer barrel and endcap in the H8 test beam line at CERN; one of its aims is to test the concepts and the final prototypes of the components of the alignment system before starting the mass production.