Journal of Materials and Engineering Structures

157-165

Authors: Rachid Bouras, Chafiâa Si hadj Mohand, Mohammed Sonebi

An adhesive mortar in fresh state is considered as a granular suspension in a complex fluid. The study of the rheological behavior of such materials involves the rheology of complex fluids, including granular suspensions, colloidal dispersions, etc... To characterize the rheological behavior of an adhesive mortar, in quasi-static regime, we use a three-parameter behavior law that includes a yield stress, a viscosity coefficient and a fluidity index. The adhesiveness of the mortar can be characterized by identifying the evolution of the adhesive force, the cohesive force and the adherence force. The mortar characteristics are measured by a commercial rheometer from Texas Instruments (TA). In this study, we use a plane-plane geometry for the Probe Tack Test to determine the adhesiveness of the materials. The rheological property of the mortar is investigated using the Vane-Cylinder geometry (figure 1.5). The mechanisms of separation and rupture in a tensile material confined between two parallel plates are studied theoretically and experimentally. This study is conducted for a materials selected for his rheological behavior (Herschel Buckley). We studied the rheological behavior and the influence of additions of organic additives on the rheological parameters intrinsic to the material, and the failure mechanisms. This study has allowed us to observe the different types of rupture.

177-188

Authors: Haider Hadi Jasim

In this paper, the fatigue performance of three types of epoxy coatings (pure, Novolac and reinforced by glass-flake) were studied in crude oils and air environments. A group of equipment is constructed in a laboratory and used in rotating bending fatigue tests of single and double layers of coats applied to ASTM A537-C1 steel. The results showed that the fatigue limit of A537 steel improved after coatings and that the fatigue limits of the coated and uncoated steel conducted in the crude oil solution was significantly lower than those obtained in the air environment. The results of the microscopic inspection indicate that there are three types of fatigue cracks initiation mechanism in steel coatings and environment affects the shape of fracture surface. In addition, the observation of the broken section of the single-layer test sample showed that it has more coat failure compared to the double layers coats.

201-214

Authors: S. Chiranjiakumari Devi, Rizwan Ahmad Khan

This current investigation was conducted to explore the influence of graphene oxide (GO) on the mechanical and durability properties of normal concrete. A total of five mixes were prepared in addition of laboratory synthesized GO ranging from 0-0.8% with an increment of 0.02% by weight of cement. The synthesized GO was characterized using SEM, FT-IR and XRD techniques. The workability, initial surface absorption and sorptivity values were observed to have reduced with increase in GO content in the cement matrix. Whereas, the ultrasonic pulse velocity (UPV), compressive and tensile strength were observed to enhance with percentage increment of GO in the concrete compare to control mix. The microstructural analysis was performed using SEM/EDX at 90 days curing age. The mix with 0.08% GO showed better result compared to rest of the mixes with GO and control mix.

233-247

Authors: Kamel Touahir, Ali Bilek, Philippe Bocher, Mustapha Beldi

The stresses induced by a mechanical contact imposed on a birefringent sphere have been studied experimentally and numerically. The birefringent sphere is machined from a birefringent parallelepiped on a high speed numerically controlled machine. The residual stresses developed in the birefringent sphere have been eliminated by a heat treatment relaxation. The technique of freezing and mechanical cutting in thin slices was used. In the case of 3D photoelasticity, the frozen stress techniques, which are very much used, may introduce residual stresses in the cut up slices. Although the means to avoid the introduction of these residual stresses are well established, these techniques remain time consuming. Slices are analyzed on a polariscope using plane polarized light and circular polarized light. The photoelastic fringes are used to determine the principal directions of the stresses as well as the values of the stresses. A numerical simulation using the finite elements made it possible to make a comparison with the experimental results. The analysis shows a good correlation between experimental measurements and numerical simulation.

259-268

Authors: Tabassum Mahzabeen Raka, Khan Mahmud Amanat

The study focuses on the finite element (FE) modelling of cold formed plain lipped C-section in shear, and combined bending and shear, which was developed using ANSYS. Hence, a parametric study on plain C-section was conducted to investigate the applicability of the direct strength method (DSM). In addition, DSM capacity curves were constructed to find out the limitations of DSM. It is found that the DSM equations for nominal shear capacity with tension field action (TFA) gives the capacity that is acceptable when full tension field action is developed while the nominal DSM moment capacity at local buckling outlines conservative results. However, the study also reveals that the DSM nominal shear capacity without tension field action provides lower capacity than the real peak capacity and therefore, it concludes that this method is more conservative.

279-292

Authors: Mokhtar Ansari, Hosein Gholi Pour, Amir Safiey

Prolixity 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.