The objective of the present manuscript is to describe the impact of polypropylene fibers on the behavior of heated concrete subjected to heating and cooling cycles at temperatures of 200, 450 and 600 °C respectively for six hours, through a series of experimental tests on mass loss, water absorption, porosity, compressive and tensile strength. For this purpose, mixes were prepared with a water/cement ratio with the incorporation of polypropylene fibers with a rate varying from 0.5 to 1.5%. These fibers were added in order to improve the thermal stability and to prevent the concrete from splitting. The results show that a considerable loss of strength was noticed for all tested specimens. The relative compressive strengths of the concretes containing polypropylene fibers were higher than those of the concretes without fibers. Also, a greater loss of mass of the polypropylene fibers compared to those without fibers was noticed when increasing the temperature. The flexural tensile strength of the concrete was more sensitive to elevated temperatures than the compressive strength and a rapid increase in porosity was observed for the fiber-reinforced concrete compared to the reference concrete. Furthermore, water absorption by the fibers is proportional to the fiber content of the concrete. Doi: 10.28991/cej-2021-03091745 Full Text: PDF
The interaction between footings placed at close proximity affects the ultimate bearing capacity, settlement, and tilt of adjacent footings, especially under seismic loading. This paper reports the numerical finite element analysis to investigate the interference effect on the seismic bearing capacity of closely spaced rigid strip footings for a wide range of footing spacings, friction angles and horizontal acceleration factor. The results are presented in terms of seismic efficiency factors, and their variation was computed with respect to the change in the spacing ratio between the two footings. The results revealed that the increase in the earthquake acceleration leads to a reduction in efficiency gains owing to the failure zone of footings interfere altering the performance of the footings.
AbstractThe objective of this paper is to describe the effect of cavities on the bearing capacity of two interfering footings based on granular soil using an exclusively experimental approach with a test model designed in the laboratory. The experimental protocol was carried out based on the variation of several parameters such as the spacing (x) (axis to axis) between the footings, and the distance (H) between the footings and cavities and between the cavities axes (L). The results highlight the effect of cavities and the interference of two strip footings on the bearing capacity factor (q) and efficiency factor (EF). Moreover, the results revealed that, in the case wherein the distance between the footings and the cavity is greater than 3, the cavity impact is eliminated.
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