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Repairing of reinforced concrete structures is currently a major challenge in the construction industry and is being put back into operation with a slight loss in load carrying capacity. Damage occurs due to many factors that reduce the strength of concrete structures and their durability. The aim of this paper is study the compatibility between three types of reactive powder concrete with (steel fibre, glass fibre and polypropylene fibre) as a repair materials and normal strength concrete as a substrate concrete. Compatibility was investigated in three steps. First: individual properties for substrate concrete were studied, these are (slump test, compressive strength, splitting strength, and flexural strength) also, for repair material these are (compressive strength and flexural strength) were determined by using standard ASTM test methods. Second: bond strength of composite cylinder for substrate concrete with different repair materials were evaluated by using slant shear test. Third: compatibility was investigated by using composite prisms of substrate concrete with different repair materials under two-point loading (flexural strength test). From the experimental results concluded, bond strength between reactive powder concrete with glass fibre as a repair material and normal strength concrete as a substrate layer is higher (17.38Mpa) compared with RPC with steel fibre (13.13Mpa) and polypropylene fibre (14.31MPa). Also, it is more compatible due to flexural strength for composite prisms (having higher flexural strength (8.13MPa). Compared with steel fibre (7.44MPa) and polypropylene fibre (6.47MPa). These results due to RPC with glass fibre have good workability with suitable flowability and glass fibre have higher tensile strength compare with other fibre.

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For utility of economical and practical construction, precast concrete is used due to its advantages such as reliability, durability, and higher quality. The appropriate selection of connection between the precast elements can have a significant influence on both the structural performance and long-term durability of such precast system. In this study, the effects of different connecting techniques on the performance of the precast composite flanged beams were experimentally and numerically investigated. The experimental program included testing up to failure under flexural loading conditions three groups of composite specimens: reference group, mechanical connecting group and chemical connecting group. The numerical assessment was done by using a finite element analysis to get a better insight and analyze the response of tested composite beams that available in the software package ABAQUS. The experimental results showed the advantageous effects of using mechanical connecting technique, as evident from improvement of the ultimate capacity or ductility of the precast composite beams. The results also showed that the predicted structural behavior using finite element analysis in terms of ultimate carrying loads, load-midspan deflection curves and crack patterns of the composite beams was in good agreement with the experimental data.

The modern architectural designs and building techniques in the constriction field need new materials. Those materials have high compressive strength, such as an Ultra-High-Performance Concrete, which abbreviates by UHPC. The UHPC is suitable to use for high-rise buildings and long-span bridges. Therefore, this study investigated the ability to produce UHPCs depends on available materials and the optimum proportion of these materials. Also, the increment of the steel fiber is needed to study its effects on the mechanical properties of the UHPC. Therefore, four Fraction Volume of steel fiber content has been adopted, which were 0%, 1.5%, 3.0%, and 4.5%. The results showed the ability to produce UHPC with a compressive strength reaches to 150 MPa, by using affordable materials. However, the increase of the steel fiber content would be improved the compressive strength of about 40% for the steel fiber content of 4.5% as well as the rupture stress increased to 160% for the same fraction. The results revealed that the reduction of the compressive strength reaches to 0.69 when used small molds.

This paper presents an optimizing design for the floor deck for the composite arch steel bridge depending on the arch flexibility (the bridge’s main component). The design is based on second-order effects using nonlinear p-delta analysis. Many variables are considered in the parametric study, which is the arch’s in-plane flexibility, the out-of-plane flexibility of the arch, and the number and stiffness of the lateral bracing between the twin arches. The design has been done by graphical design software SAP2000 and based on AISC and AASHTO specifications. A numerical example is studded herein for the new proposed bridge of Batta in Al-Hilla city in Iraq which crossover Al-Hilla river for a width of 108m from bank to bank, the bridge has an overall width of 18 m including two lane-two way of 15.6 m width and walkways of 1.2 m on both sides. This study’s main objectives are the number and size of floor beams, deck thickness, and hence the overall weight of the bridge will be minimum, the goal of design is to select the lightest and most economical and practical composite floor decks. It has been concluded that the deflection decreases with the increase in the number of the floor beam, and the best result was the case of the distance between the floor beam is 1.95 m with a deflection of 71.95 mm, meaning that the flexibility is less as the number of floor beam increases. As for the change of the arch’s cross-section, the best result of the lesser girder deflection was in the case that the arch section with dimensions (0.8 x1.2x0.035) m. This indicates that the greater the moment of inertia, which leads to less deflection for cross over the main girder.

Spaceframe is a structural roofing system that generally made of steel tubes connected by ball joints which is called MERO jointed space frame structures and mostly used for covering large space area. In addition, some advantages could be obtained with such a system, for example lower weight, high strength-to-weight ratio and low cost. This study aims to use such a known roof structure for a composite structure in which Ultra-High-Performance Concrete slabs are used to withstand various loads as a structural floor system. Various inclinations of the main elements for space frames were tested, namely 30 °, 45 ° and 60 °. The composite effect is accounted for by testing composite and non-composite samples. The test results were evaluated and compared against several performance indices, such as: Ultimate load, stiffness, hardness, ductility, ductility index and absorbed energy. Test results have shown that spaceframe models with an angle of 60 ° have the highest load-carrying capacity compared to other angles and the highest toughness compared to various techniques. Putting together 40mm UHPC slab panels reflected a slight increase in the models used in this study than traditional spaceframe samples.

In this study, a novel test technique is used to experimentally study the behavior and performance of the socket joint used to stabilize the precast columns embedded in a foundation that is subject to lateral loading. The test program included the testing of five test specimens, which represent the condition of the prefabricated concrete columns, which are embedded in the foundation. five specimens were divided into two groups based on the embedded length. Group one consists of two samples with a smooth interface and different embedded lengths. Group two consists of three samples with constant embedding length, two of them with a smooth interface and the other with a rough interface. Self-compacting mortar (SCM) was used as the adhesive material to fill the gap between the concrete column and the base for the samples of the first group, while the non-shrinking mortar and the self-compacting mortar (SCM) were used as adhesive material. Fill the gap between the Concrete column and the base in the second group. The practical results showed the possibility to use the developed test method as an alternative test method for comparing and representing a relationship between the different cases of socket connections. It has also been found that the roughness of the interface increases the bearing capacity for the embedded length, which corresponds to and is less than the depth of the concrete column, otherwise it is not required.