Materials and Structures

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    Analysis And Behavior Of Semi-Rigid Composite Joints
    (University of Khartoum, 2015-05-14) Ahmed., Hasab Elsied Ibrahim Abdalla ; Osama.M. A. Daoud ; Building Technology
    Semi-rigid behavior of joints in steel and composite structures is a new approach for modeling the joint response. The objective of this research is to perform design analysis of semi-rigid composite steel-concrete end plate beam to column joints. The literature of semi-rigid composite joints was first investigated, and then one of the proposed methods for design of composite joints was selected in this study. Based on this method a computer program was developed to compute the moment capacity of semi-rigid composite joints. The results of the predicted moment capacity were compared with previous test results. Another objective is to perform parametric study for the effect of the design factors on moment capacity, and to compare the moment capacity of the semi-rigid with the moment capacity of the rigid connections. Also a computer program was used to develop the moment-rotation curve for composite cleated connections. FORTRAN programming language was used to develop the computer programs, the results are presented in tables and figures to know and understand the behavior of these connections. The design analysis was applied to different beam sections,and for different ratios of reinforcement. This study shows that the moment capacity of semi-rigid end plate beam-to column connection increased with increased concrete slab depth, reinforcement ratio, beam flange thickness and width, beam web thickness, and shear studs numbers. For the end plate connections the predicted moment capacity are generally slightly smaller than the equivalent test results
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    Assessment Of Concrete Admixtures Used In Khartoum State
    (University of Khartoum, 2015-05-14) Taher, Muaz Abu Baker Abu Baker ; Osama M. A. Daoud ; Structural Engineering
    There exists a large increase in the use of concrete admixtures especially the increasing use of ready-mixed concrete due to the growth in the construction industry in Khartoum State in the last few years. The aim of this study is to evaluate the concrete admixtures used in Khartoum state regarding their effects on the properties of fresh concrete (workability) and hardened concrete (strength). To achieve this purpose, the main constituent materials of concrete mixes (cement, aggregates, and water) were brought from different sources around Khartoum state, and preliminary tests had been carried out to make sure that the materials conform to the standards and specification, and to select the appropriate dose of the admixtures (depending on the recommended dose). A testing program was prepared including four concrete mixes: the ordinary reference mix without admixture, and other three mixes with different types and doses of concrete admixtures. Results of preliminary tests on the constituent materials of concrete have shown that they conform to the specifications and standards required for use in structural concrete. Results of tests conducted on fresh and hardened concrete have shown that the benefits of using concrete admixtures in the environment of hot weather of the Khartoum State during most of the year, the improvement of the properties of fresh and hardened