حيدر حسين صالح الخضري

Abstract Slab–Column connection is one of the critical structural joints in building construction, since there are special design requirements that must be achieved. This paper investigates RC slab–column connections under eccentric load using a built-in 3-Dimensional Nonlinear program of fnite element in the pre- and post-cracking levels and up to the ultimate load. The concrete is simulated as isoparametric brick element, and the reinforcement bar elements are assumed to be built into isoparametric brick elements. With regard to load–defection responses and ultimate strength capacity, a good coincidence is achieved for FEA and experimental results with maximum diference 1.6% for ultimate strength. In addition, the structural performance investigation of slab–column connection is carried in terms of the efectiveness of applied load types, shear reinforcement and slab thickness. It can be concluded that the increase in loading eccentricity cause decreasing in ultimate load 20.5 to 40% in comparison with case of e=0, which is one of conclusion of this research. Also, the use of shear reinforcement (48 stirrups of Φ10 mm) in the fat slab connection with columns had more efects than slab depth. It is found that the ultimate load capacity increases about 34.4% with e=0.0, while it decreases about 22% with e=0.45 m when compared with slab–column connections without shear reinforcement (e=0.0). In addition, as the slab thickness increases from 150 to 200 mm, the ultimate load increases about (25%) when compared with case of (e=0.0), while the ultimate load increases about (2.3%) when compared with the same case of (e=0.0), which means that the increment in the slab thickness can be considered as compensation for the efects of increasing in load eccentricity. Also, for the slab–column connection without shear reinforcement, the related formula of ACI-code gives a good agreement in terms of ultimate load capacity in comparison with the results of adopted FE model with maximum diference 4% as the unbalanced moment was increased, while for usage of shear reinforcement in slab–column connection, the formula of ACI-code becomes more conservative with maximum diference 10% with increasing of unbalanced moment.

As a computer technique, Artificial Neural Networks (ANNs) have expanded in use with engineering fields. ANNs have been used in many civil engineering problems and some of them were used in the design of concrete structural elements and have shown a good degree of success. This paper presents an ANN model for the strength design of reinforced-concrete hydraulic structure according to the requirements of the Engineering Manual 1110-2-2104. Structural design is a sequential process needs iteration, assumption, checking the limits, ...etc, and that can be programmed with some judgments of the designer. 288 cases of design samples have been calculated using excel sheets and Microsoft visual basic programming language. 200 samples of design randomly selected have been used for training of (4-10-10-2) ANN model. 50 samples have been selected for validation, and 38 for prediction processes. The predicted design outputs were the thickness of hydraulic concrete section and corresponding steel reinforcements. Visual Gene Developer software of ANN prediction for general purposes has been used with a feed-forward neural network with a standard back-propagation learning process. The suggested artificial neural network model has predicted the output data of design for concrete sections, and the results have shown a satisfactorily match with the actual output data of design

Fiber reinforced material (FPR) has become an effective alternative reinforcement for concrete constructions owing to their higher ultimate strength in tension and strongly anticorrosive properties. However, the low ductility behaviour of FRP reinforcing concrete structure (FRP-RC) is appeared comparing to high ductility of conventional steel reinforcing concrete structures (S-RC). Successfully hybridization of reinforcement by combining FRP and steel rebar presents effective solution to migrate corrosion of steel rebar in steel reinforcing concrete constructions and advanced ductility of FRP-RC structures. Also, a good improvement is achieved in structural performances of concrete beams in terms of ultimate strength, central deflection, number cracks, and crack width. In this paper, a theoretical prediction analysis model of hybrid reinforcing concrete (H-RC) members reinforced by FRP and steel rebar presents. The moment-curvature relationship is predicted to achieve load-deflection curve and bending moment capacity of beams. A good agreement has been indicated from verification between results of predicted theoretical model and 19 experimental results of other authors. The hybrid reinforcement in HRC section can be replaced by equivalent steel ratio to conduct limitations of reinforcement ratio. The ductility index of H-RC members is measured to reference S-RC member, while the ultimate strength index is measured to reference FPRC member. A critical limitations of (

Fiber reinforced concrete is an improved type of concrete that containing fibers randomly distributed inside it. Usually, the mechanical properties of concrete have been developed namely, compressive, flexural, and tensile strength by adding the fibers. In addition, the fiber makes the concrete very durable, tougher and lower permeability. This paper aims to enhance the concrete mechanical properties by adding polypropylene fibers in combination with high performance cement as a partial cement replacement. The combination of both polypropylene fibers and high performance cement in concrete gave excellent values of flexural, tensile and compressive strength. Seven percentages of polypropylene fibers were used while two percentages of high performance cement were used, in addition to normal specimens of concrete without any admixtures. Test results give a well improvement by using both polypropylene fibers and high performance cement. The flexural strength and the tensile strength are increased significantly from 2.7 to 14.5 MPa, and from 1.9 to 7 MPa, respectively. While concrete strength of compression increased from 30.1 MPa to 42.9 MPa due to inclusion of polypropylene fibers and high performance cement. The concrete specimens with including both high performance cement and polypropylene fibers had adequate strength to counteract further cycles of loading after releasing 1st failure load.

The thin-walled plate and foam of low material is components of sandwich panels, one of the attractive engineering structures mixed between different two materials to accomplish high ultimate strength integrated with light weight structures. Usually, the sandwich panels composed of two thin steel faces with ultra-strength are supported and separated between them by foam core. This paper deals with presently design expression of thin-walled steel faces supported by foam simulated using finite element analysis (FEA). Numerous waves of FE models introduced to explore and analyze the adequacy of present approach for thin-walled design. Also, investigation of FE simulation model containing geometry, dimensions, loading system and supporting pattern are presented. The FEA model provides a good acceptance with experimental results. However, for sandwich plate element with low (b/t) ratios, the formulae of design appeared safety solution, while for high (b/t) ratios (slenderness plate) becomes over estimated. Finally, formula of designing sandwich plate with local buckling is proposed in unification form.

In this research, “Slide” program was used to analyze seepage flow under the hydraulic structure through isotropic and anisotropic soils and its effect on structures with cut-off at downstream, at upstream, and at both of them. The distribution curves of uplift pressure along the floor had been reached at downstream for different degrees of anisotropy from the horizontal axis. The effects of anisotropy on uplift pressure . The analysis process depends on a finite element method. Eight-noded quadratic elements to represent the porous media. The maximum values of uplift pressure under the structure with cut-off at downstream are seen at 180˚, and 0˚ inclination angles and the minimum values are seen at 90˚ inclination angle, the maximum values of uplift pressure under the structure with cut-off at upstream are at 90˚ inclination angle and the minimum values are at 180˚, and 0˚ angles, and the maximum values of uplift pressure under the structure with cut-off at upstream and downstream are at 90˚ inclination angle and the minimum values are at 180˚, and 0˚ inclination angles but the relationship is reversed after x=0.5. The quantity of seepage in downstream side of the structure with a cut-off at downstream was 0.546 m3 /day, at upstream was 0.396 m3 /day, and at both of them was 0.501 m3 /day. The quantity of seepage for anisotropic soils was calculated for all cases. KEYWORDS:pressure head,uplift pressure, seepage, isotropic soil and anisotropic soil.