الدكتور حيدر مهدي عبد الجواد النفاخ

The flexure behavior of reinforced concrete dapped-end beams (D-E) is assigned in this paper. Reinforced concrete D-E beams, that failed in flexural have been analyzed using the ABAQUS software. The ABAQUS model represents the nonlinearity, such as, post cracking tensile stiffness of the concrete, stress transfer transversely the cracked blocks of concrete. The failure mode of D-E beams is demonstrated fairly well using the present numerical model, and the maximum load expected is very near to the failure load of test results . In this study explicated some of parametric study such as shear span to depth ratio (a/d), concrete compressive strength, and the main D-E reinforcement on the behavior of the beams. The main steel amount has the most significant effect on the performance of flexural strength of RC D-E beams. Maximum load and displacement for various types of flexural failures in beams have been represented. In general this investigation demonstrates that the D-E beams flexural strength is influenced by the preceding parameters.

This research submits theoretical and experimentalrealization of shear behavior of RC I-beams with polypropylene fiber with different volume fraction of plastic fiber as additive. The enhance of the sustainability of structural elements through the development of its mechanical performance by adding new materials such as plastic raw materials has become more important in the current period , particularly I- beams that was used in the long spans structure to become more environmentally-friendly. Seven specimens were tested in this study and only the amount of fiber volume fraction was varied. Experimental results showed that the ultimate strengths are increased in range (4.4% to 35.27%) that of control IB-1 for the tested beams containing Polypropylene Fiber Reinforced Concrete (PPFRC) with varied amount percentage of fiber material. Crack arrest mechanism of polypropylene fibers, and compressive strength of concrete increased in range (7.42% to 29.3%) that of plain concrete, and improved the tensile response in range (8.36% to 92.7%) that of plain concrete, limited crack propagation. So, improved behavior was obtained. ANSYS 11,Finite Element models software are used to emulate two tested I-beams. 3D- nonlinear solid elements was utilized to model the concrete, while, the steel reinforcement was demonstrated by spar element.It was found that the general practices of the FE models demonstrated acceptable concurrence with perceptions and information from the experimental tests.

The ability to reasonably predict the response of steel structures under fire effects is of great importance in structural fire safety design. This paper presents neural networks prediction of axial load capacity for steel columns in fire. An algorithm of back propagation neural network with the log-sigmoid activation function is adopted because of its precision and results enhancement of foretelling. The legitimacy of the technique is tried by contrasting and distributed test information on steel columns at surrounding and elevated heat. The examinations demonstrate such technique gives great correlation with test result. Parametric studies have been done to evaluate the impacts of cross sectional shape, slenderness ratios and eccentricity of loading on the carrying capacity of steel columns under fire. The slim sections of steel columns with slenderness ratio domain (100-140) react distinctively by showing an abundantly decreased rate of loss in strength within the temperature domain (20°C - 300°C). This domain diminishes further with expanding slenderness ratios, and for middle columns with slenderness ratio domain (40-80), is like that of stumpy columns however at decreased buckling stress. Be that as it may, in this scope of (L/R) ratios the lessening in stress with expanding temperature is regular and demonstrates no sudden drop, because of the collaboration amongst buckling and yielding. On other hand, the eccentricity of loading on the carrying capacity of steel columns under fire shows that the slender column, (slenderness ratio) greater than 120, the column demonstrates a diminishing impact of used eccentricity of loadings with expanding slenderness ratios. This might be as a consequence of more impelled thermal bowing that is straightforwardly relative to the column length. And the load-eccentricity characteristics of the intermediate column, (slenderness ratio) domain (20 – 60), are schemed at increasing temperature gradient. It is fascinating to observe that the eccentricity of the limit of maximum column load capacity slightly effected with temperature gradient. It is trusted that the important data gave in this work will be helpful in giving a superior comprehension on the genuine behavior of steel sections in fire and a great step in improving the method of design.

Nonlinear Analysis of High Strength Concrete Deep Beams by Using Finite Element Method.

Nonlinear Analysis Of Reinforced Concrete Beams Under Combined Bending And Torsion With And Without Fiber By Using Finite Element Method .

تم نشر البحث الموسوم MODELLING OF DAPPED-END BEAMS USING ABAQUS SOFTWARE في مجلة International Journal of Civil Engineering and Technology (IJCIET) Volume 9, Issue 1, January 2018, pp. 1–10,والتي تقع ضمن مستوعبات سكوبس.