Journal of Materials and Engineering Structures
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Effect of a crack emanating from notch on a composite pipe subjected to buckling
Get PDFNew pipelines made with composite materials have to be well-designed for better mechanical performances. Recommendations for sizing stratified pipes have been proposedfor different combinations of loads. In this context, our paper focus on buckling on laminated composite pipes, using numerical simulation. As a first part, we study free-defect pipes buckling for different pipe diameters, wall thicknesses and fibers orientation. In a second part, we evaluate the influence of defects (notches and crack due to notches), their parameters (size, orientation) and mechanical constraints (pipe under pressure, boundary conditions) on the structure. Results show a strong dependence of the size of the notch to the stability of the structure, amplified by the fibers orientation. Thus, for fibers oriented at an angle close to 20°, pipes manufacturing under these conditions show a particular strength of the structure. The crack length (independently on its orientation) seems to have no significant effect on the buckling factor and therefore the structure integrity, for transverse-orientated fibers and while their orientation go beyond 40°. The main variations are observed when fibers orientation is in the range from a few degrees up to 40°. Results are and discussed according the orientation of crack and fibers
Study of Mortars Made with Natural and Artificial Pozzolans
Get PDFThe objective of this work is to evaluate the thermal activation potential of clay soils, particularly the clay fraction of dam mud, for the production of artificial pozzolan which can be substituted to cement in concrete and mortars applications and also to make a comparative study with the natural pozzolan available in the area of Beni Saf in considerable quantities. The research study is carried out on three mortars 10, 20 and 30% of natural pozzolan of Beni Saf and artificial pozzolan from the mud calcined at 850 ° C / 3 hours of the dredged sediments of the dams of Fergoug and Ouizert, and on a control mortar without additions for the need of comparison. Several physical, mechanical, microstructural and sustainable tests have been carried out to carry out this research study: maneuverability in the fresh state, impeded shrinkage, mechanical performance, absorption, acid attack (5% CH3COOH, 5% HNO3 and 5% H2SO4), mass loss and pH reading follow-up in the hardened state. Compressive strengths indicate that pozzolan-based mortars have the best results in particular over the long term, whereas the results of acid attack tests show that the calcined mud has a significantly greater influence than natural pozzolan
Flexural Performance and Toughness Evaluation of Hybrid Steel- Polypropylene Fibre Reinforced Self Compacting Concrete
Get PDFThe paper presents the results of an investigation conducted to study the influence of fibre hybridization on the compressive strength, flexural strength, flexural fatigue and flexural toughness of the HybridFiber Reinforced Self Compacting Concrete (HyFRSCC). The Steel Fibers (SF) and Polypropylene Fibers (PPF) at 1%by volume of concrete have been used. The PPF and SF proportions used are 100%PPF, 75%PPF + 25%SF, 50%PPF + 50% SF, 25%PPF + 75%SF and 100%SF. The flexural toughness parameters were calculated using procedure laid down in JCI Method, ASTM C-1018 C and ASTM 1609/C 1609 M. The flexural fatigue tests were conducted at stress levels of 0.65, 0.7, 0.75, 0.8, 0.85 and 0.9. The Weibull parameters have been calculated using the graphical method and the method of moments. The results indicate that the mix with a fiber combination of 25%PPF + 75%SFcan be adjudged as the optimum combination for HyFRSCC in terms of compressive strength, flexural strength and flexural toughness. Gradual replacement of steel fibers with polypropylene fibers hasbeen found to reduce the variability in fatigue life data of HyFRSCC
RETRACTED : Composite parameters analysis with boundary element method
Get PDFThis article has been retracted at the request of the Editors-in-Chief, according to the Publication Ethics Policy and Publication Malpractice Statement.Please see: http://revue.ummto.dz/index.php/JMES/about/editorialPolicies#custom-2 This note is published, 26 June 202
Numerical Analysis of the Tetrapylon Roman's Triumphal Arch of Tebessa: A Case Study.
Get PDFThe Tetrapylon Roman Triumphal Arch or commonly called 'Caracalla Gate', located in Tebessa City (Northern Algeria), is considered as one of the most distinctive type of arches associated with the ancient Roman's architecture. This historical monument, erected in the 3rd century, was dedicated to the Roman Emperor Caracalla. In the 6th Century the Caracalla gate was enclosed in the Byzantine old city, built by the General Salomon. Although the monument is still standing, over time, it suffered apparent damages. The conservation and restoration of this monument is actually a major preoccupation for the concerned authorities. In this paper a 3D numerical analysis of the deformations and global stability of the gate are presented. The numerical results obtained were compared to previous site survey and measurements, and were found to be in good agreement. The results revealed that part of the monument damages and deformations occurred following the construction of the Byzantine walls. In its actual state, the monument was found sufficiently stable, and the restoration would not affect its firmness, if appropriate materials and techniques are deployed
Microstructural study of Styrene Polyacrylic (SPA) latex modified mortars
Get PDFIn this paper, the influence of the styrene polyacrylic (SPA) latex polymer on the microstructural properties of limestone mortars has been studied. For this purpose, five mortars were developed with different dosages of the SPA latex (0%, 2.5%, 5%, 7.5% and 10%) by weight of cement. This research was carried out using XRD, FTIR, and SEM analyses. The results of XRD and FTIR studies showed that the addition of SPA latex can increase the portlandite content of polymer-modified mortars (PMMs), compared to the control mortar. In addition, the moist environment promotes the Ca(OH)2 consumption in PMMs at early age and accelerates the hydration. Moreover, the SEM analysis revealed that the cement hydrate structure of the reference mortar is loose. In contrast, the hydrates of the PMMs were covered by a polymer film or membrane, and the pore structure is significantly affected by the filling effect the micropores by the latex particles
Effect of Chemically Modified Banana Fibers on the Mechanical Properties of Poly-Dimethyl-Siloxane-Based Composites
Get PDFThe study presents the mechanical properties of polymer-based composites reinforced with chemically modified banana fibers, by alkalization in different concentrations of sodium hydroxide (NaOH). The fiber weight fraction has a great effect on the mechanical properties of the composites. Stiff composites were obtained at 6 wt% fiber fractions with Young’s modulus of 254.00 ±12.70 MPa. Moreover, the yield strength was 35.70 ±1.79 MPa at 6 wt% fiber fractions. However, the ultimate tensile strength (UTS) and toughness of the composites were obtained at 5 wt% fiber fractions. Statistical analyses were used to ascertain the significant different on the mechanical properties of the fibers and composites. The implication of the results is then discussed for potential applications of PDMS-based composites reinforced with chemically modified banana fibers
Seismic performance of mid-rise code-conforming X-braced steel frames
Get PDFProlixity and complexities inherent in the nonlinear dynamic analysis (NDA) impel engineers to lean towards nonlinear static analysis (NSA) in practice. This paper partly explores differences and similarities in responses obtained from these two simulation techniques. The scope of the study is narrowed down to ubiquitous regular code-conforming mid-rise steel X-braced frames. Different common lateral load patterns are coupled with NSA to study their interactive effects on responses. The modal nonlinear static analysis is also carried out, where deemed necessary. NDA using three different earthquake records are conducted as well, to validate NSA results. Results of nonlinear analyses are undertaken to compare provisions of seismic rehabilitation code with those of seismic design codes. Base shear, story drift, lateral displacement profile obtained for each model are independently thoroughly discussed. Eventually, some suggestions to improve design code requirements are accordingly provided, as applicable
RETRACTED : Mechanical and structural reliability based algorithm optimization
Get PDFThis article has been retracted at the request of the Editors-in-Chief, according to the Publication Ethics Policy and Publication Malpractice Statement.Please see: http://revue.ummto.dz/index.php/JMES/about/editorialPolicies#custom-2 This note is published, 27 June 202
Workability, compressive strength and initial surface absorption of laterized concrete
Get PDFThis paper investigated the workability, compressive strength and initial surface absorption of plasticised laterized concrete at the water/cement ratios of 0.30, 0.50 and 0.70. Slump, compressive strength at 7, 14, 21 and 28 days and initial surface absorption after 10 minutes (ISA-10) at 28, 60 and 90 days were determined at the laterite contents of 0, 20, 40, 60, 80 and 100%. ISA-10 was also assessed at 28-day strengths of 20, 25 and 30 N/mm2. Results showed that superplasticiser dosage increased with increasing content of laterite and for economic dosage laterite content should be limited to 40%. At equal water/cement ratios, compressive strength reduced with increasing content of laterite and ISA-10 increased with increasing content of laterite. The results also showed a strong relationship between ISA-10 and compressive strength and that laterized concrete, when specified on the basis of strength, would have resistance to initial surface absorption comparable with that of the conventional concrete if laterite content is limited to 40%. Hence, for good workability, compressive strength and permeation resistance, laterite content of concrete should be limited to 40%