Pushover Tests on Unreinforced Masonry Wallettes Retrofitted with an Innovative Coating: Experimental Study and Finite Element Modelling

This paper investigates the mechanical contribution of an innovative coating applied on masonry wallettes compared to a traditional one. In both cases, the multifunctional coatings were insulating coatings intended for thermal refurbishment, but they could also be used to retrofit masonry. Uncoated specimens as well as coated ones were submitted to pushover tests to establish the strength gain. URM walls experienced brittle failures while the coated walls exhibited significant strength gains and strong ductility. The corresponding finite element models were developed. The behaviour of the URM walls was reproduced accurately in terms of strength and failure pattern. Models involving the coatings were used to partially retrieve the behaviour and to highlight the issues of a continuum approach.

BIOM-06. MOLECULAR SIGNATURES UNDERLIE THE DISTINCT FAILURE PATTERNS OF MALIGNANT GLIOMAS

BACKGROUND Malignant gliomas exhibit varied failure patterns upon recurrence; however, genomic backgrounds of these distinct phenotypes have not been evaluated. We aimed to explore the genomic traits associated with distinct failure patterns in malignant glioma patients. METHODS This study involved 272 malignant glioma patients. Failure pattern was defined for the spatial relationship between recurrent tumor and the original tumor as follows: local recurrence (LR), remote recurrence, leptomeningeal seeding (LMC), and combined failure pattern. Molecular characteristics underlying different failure patterns were investigated for the mutation profile, copy number variation (CNV), and transcriptomic signatures. RESULTS Local recurrence was the most prominent failure pattern (62.9%), followed by combined recurrence (22.8%). Multivariate Cox regression analysis confirmed failure pattern as one of the independent prognostic factors. Patients with combined failure patterns exhibited the worst prognoses, whereas patients with remote recurrence exhibited the most favorable outcomes (median overall survival = 11.4 and 25.2 months, respectively). In IDH1-wild type glioblastoma (GBM) patients, TERT and PIK3CA mutation were significantly associated with the development of combined failure pattern and leptomeningeal seeding, respectively (p-value=0.015 & p-value=0.004, respectively). Transcriptomic analysis exhibited that inter-neuronal synaptic transmission was enriched in GBMs with combined failure pattern and this finding was further validated in proteomic analysis; neuronal myelination and synaptic transmission-related pathways were upregulated in GBMs which exhibited combined failure pattern. CONCLUSIONS Collectively, we demonstrated that the inherent molecular characteristics of the tumors might contribute to the eventual relapse patterns; tracking their evolutionary pathways may unravel novel therapeutic vulnerabilities of these tumors.

Bearing capacity of rectangular footing on layered sand under inclined loading

Purpose: The study presents the numerical study to investigate the bearing capacity of the rectangular footing on layered sand (dense over loose) using ABAQUS software. Design/methodology/approach: Finite element analysis was used in this study to investigate the bearing capacity of the rectangular footing on layered sand and subjected to inclined load. The layered sand was having an upper layer of dense sand of varied thickness (0.25 W to 2.0 W) and lower layer was considered as loose sand of infinite thickness. The various parameters varied were friction angle of the upper dense (41° to 46°) and lower loose (31° to 36°) layer of sand and load inclination (0° to 45°), where W is the width of the rectangular footing. Findings: As the thickness ratio increased from 0.00 to 2.00, the bearing capacity increased with each load inclination. The highest and lowest bearing capacity was observed at a thickness ratio of 2.00 and 0.00 respectively. The bearing capacity decreased as the load inclination increased from 0° to 45°. The displacement contour shifted toward the centre of the footing and back toward the application of the load as the thickness ratio increased from 0.25 to 1.25 and 1.50 to 2.00, respectively. When the load inclination was increased from 0° to 30°, the bearing capacity was reduced by 54.12 % to 86.96%, and when the load inclination was 45°, the bearing capacity was reduced by 80.95 % to 95.39 %. The results of dimensionless bearing capacity compare favorably with literature with an average deviation of 13.84 %. As the load inclination was changed from 0° to 45°, the displacement contours and failure pattern shifted in the direction of load application, and the depth of influence of the displacement contours and failure pattern below the footing decreased, with the highest and lowest influence observed along the depth corresponding to 0° and 45°, respectively. The vertical settlement underneath the footing decreased as the load inclination increased, and at 45°, the vertical settlement was at its lowest. As the load inclination increased from 0° to 45°, the minimum and maximum extent of influence in the depth of the upper dense sand layer decreased, with the least and highest extent of influence in the range of 0.50 to 0.50 and 1.75 to 2.00 times the width of the rectangular footing, respectively, corresponding to a load inclination of 45° and 0° Research limitations/implications: The results presented in this paper were based on the numerical study conducted on rectangular footing having length to width ratio of 1.5 and subjected to inclined load. However, further validation of the results presented in this paper, is recommended using experimental study conducted on similar size of rectangular footing. engineers designing rectangular footings subjected to inclined load and resting on layered (dense over loose) sand. Originality/value: No numerical study of the bearing capacity of the rectangular footing under inclined loading, especially on layered soil (dense sand over loose sand) as well as the effect of the thickness ratio and depth of the upper sand layer on displacement contours and failure pattern, has been published. Hence, an attempt was made in this article to investigate the same.

Predicting the response and perforation of fibre metal laminates subjected to projectile impact

Purpose The purpose of this paper is to predict the response and perforation of fibre metal laminates (FMLs) subjected to impact by projectiles at different velocities. Design/methodology/approach A finite element (FE) model is constructed in which recently proposed dynamic constitutive models for fibre reinforced plastic (FRP) laminates and metals are used. Moreover, a recently developed dynamic cohesive element constitutive model is also used to simulate the debonding between FRP laminates and metal sheets. The FE model is first validated against the test data for glass laminate aluminum reinforced epoxy (GLARE) both under dropped object loading and ballistic impact, then used to perform a parametric study on the influence of projectile nose shape on the perforation of FMLs. Findings It is found that the present model predicts well the response and perforation of GLARE subjected to impact loading in terms of load-time history, load-displacement curve, residual velocity and failure pattern. It is also found that projectile nose shape has a considerable effect on the perforation of GLARE FMLs and that the ballistic limit is the highest for a flat-ended projectile whilst for a conical-nosed missile the resistance to perforation is the least. Originality/value Recently developed constitutive models for FRPs and metals, together with cohesive element model which considers strain rate effect, are used in the FE model to predict the behaviour of FMLs struck by projectiles in a wider range of impact velocities; the present model is advantageous over such existing models as Johnson-Cook (JC) + Chang-Chang and JC (+BW) + MAT162 in terms of failure pattern though they produce similar results for residual velocity.

Tensile behavior of a Brazilian Disk Containing non-persistent Joint Sets Subjected to Diametral Loading: An Experimental Investigation

Structural defects are part of the inherent characteristics of rock masses. They can be found in the form of fishers, joints, and beddings and can be divided into persistent or non-persistent one. The coalescence of non-persistent cracks may lead to the formation of persistent joints under the tensile stress field, leading to instability of rock mass. The mechanical behavior of non-persistent jointed disks under tensile stress has essential implications for rock engineering structures. In this paper, concrete Brazilian disks containing open non-persistent joints were constructed and subjected to diametral loading to investigate the effect of this kind of joint parameters on the tensile strength and stiffness of disks. The effect of some parameters, such as joint continuity factor (the relationship between joint length and rock bridge length), bridge angle, joint spacing, and loading direction with respect to joint angle were investigated to estimate the tensile strength and stiffness as well as failure pattern. The results of experiments revealed that the tensile strength, stiffness, and failure pattern of Brazilian disks are highly affected by non-persistent pre-existing crack parameters. The increase of joint continuity factor and loading direction leads to an increase in tensile strength and a decrease in stiffness. However, when bridge angle and spacing increase tensile strength rises, and the former decreases stiffness while the latter results in its reduction. Finally, all the parameters significantly affect the failure pattern, and some failure patterns such as step-path failure, splitting, or sliding may occur as a function of non-persistent joint parameters.