In line with the development in the construction sector and continuous need for many of concrete structures that meet the need of continuous population increase in Iraq. It became necessary to think in concrete construction to be more economical through the use of alternative raw materials in concrete production. Also it helps to rid of materials that cause environmental problems.The first objective of this paper is to produce concrete less expensive. Second, reduce pollution of the environment in terms of using a type of glass which cannot be recycled in other industries. This type of glass will be used as a raw material in the concrete production instead of cement or sand by specific rates. Research results were carrying a good indicator about compressive strength when using a glass powder instead of cement; especially when the glass was grinding at a more time. When the compensation ratio instead of cement was 20%, and using glass was grinding by 16 hour; the results were a good. They were (31.99, 44.9, 51.64) MPa in age (7, 28, 56) respectively, compared with standard samples which were (22.4, 36.51, 43.2) MPa .
This paper aims at exploring the most important challenges which are facing the construction contracts in Iraq, and trying to analyze these challenges from various aspects. Addition, we have put necessary recommendations to support this sector through some notes and appropriate plans. Challenges are classified into eleven major problems (Political Problems, financial problems, administrative problems, problems related to the tender documents (contracts, drawings), problems related to the specifications and materials adaptation (Quality), problems related to the contract parties themselves, problems related to the sector environment, problems related to the natural environment, problems related to the arbitrations and disputes solving, problems related to the technology uses, problems related to the career ethics). These varieties have been agreed upon through questionnaire that was made for a number of the relevant authorities about the challenges facing them in construction sector. Each one of them contains a minor problems, it will be discussed such as (Rates burning due to intense competition between contractors, awarding the bid to the lowest prices not to the most accurate, delaying paying owed payments by the owner, the changing value of currency exchange). Finally the recommendations and appropriate procedures to avoid these problems, it was (Price estimation before tendering, Awarding the nearest price, rejecting offers less than 25% of the estimated), and there is other recommendations we have mentioned in this paper for another more challenges.
This paper presents a parametric study using finite element analysis of twenty six reinforced concrete circular deep beams. The considered parameters are loading type (partial and full), diameter, height and width of the circular beam, in addition to number of supports. It is concluded that applying a central partial uniformly distributed loading by 33-100% of the span length increased the load capacity by about 4-39%, and at the same time, decreased the maximum deflection and torsional moments by about 10-30% and 4-26%, respectively as compared with equivalent concentrated central loading. Increasing beam diameter by 33-167% led to decrease the load capacity by about 7-35%, while the deflection and torsional moments increased by about 41-265% and 24-77%, respectively. The load capacity and torsional moments increased by about 14-68% and 14-86%, respectively whereas deflection decreased by about 7-23% when the height of beam increased by 11-56%. The load capacity, deflection and torsional moments increased by about 163-458%, 54-83% and 160-451%, respectively when the circular beam width increased by 50-150%. Finally, it is found that the load capacity increased by about 85-365%, while the deflection and torsional moments decreased by about 24-56% and 10-46%, respectively when number of support increased by 25-100%.
The current paper presents a review of some previous experimental and theoretical studies concerning reinforced concrete (RC) curved or ring beams, behavior and strength. Due to curvature, it is necessary to include torsional effects in the analysis and design. The most effective parameters worth to be reviewed are; ring diameter, number of supports, width of beam, concrete compressive strength, and width of bearing plate. There are different analysis methods to estimate the load capacity and behavior in addition to finite element analysis. From the previous studies it was concluded that increasing ring diameter decreases the load capacity, while increasing number of supports, width of beam, concrete compressive strength, and width of bearing plate increases the load capacity due to the increase in beam section or its properties. RC ring beams fail in flexure, while the deep ring beams fail in shear in a manner similar to straight beams. Plastic analysis and strut and tie model (STM) are useful tools to analyze curved or ring deep beams effectively. Furthermore, the three-dimensional, nonlinear finite element modelling is ideal for predicting the behavior of RC curved deep beams.
Due to the corrosion that occurs in internal steel reinforcement; many of steel reinforced concrete structure are at risk of collapse. The budget that will be developed to address this risk in terms of replacement or repair of damaged concrete structures will be very high for the owner or responsible authorities. Alternatives to bare steel have been used including stainless steel, galvanized steel, epoxy-coated steel and cathodic protection, with limited effectiveness. The characteristics of fiber reinforced polymer (FRP) bars like the high tensile strength, inability to corrode, and light weight; it has become the focus of decision-makers to use it instead of steel in internal reinforcement for future concrete structures. In this research, we have investigated flexural behavior in reinforced concrete beams with bars from bars from carbon fiber-reinforced polymer (CFRP), bars from high tensile steel (HTS), and glass fiber-reinforced polymer (GFRP) under static load. Two groups from samples were used, in the first group will show the effect of the type of reinforcement. In the second group will show the effect of the type of reinforcement with different concrete strength. It found these kinds of materials to be very is effective to deal with analysis and the proposed simulation of the material in this study are able of forecast the real behavior of reinforced concrete beam by FRP bars in terms of failure load, and load-deflection behavior.
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