Samarra Journal of Engineering Science and Research

This work investigates the influences of ribs and perforated ribs on heat transfer in square channels. The circular perforated rib was selected in this work. The study theoretically analyses parameters of the thermal performance, which includes Nusselt number, heat transfer rate, and air temperature distributions along the duct centreline for different loads and Reynolds numbers. The results indicated that by using the ribs in the channel, the heat transfer rate, heat transfer coefficient, and Nusselt number increased. The heat transfer rate, heat transfer coefficient, and Nusselt number also increase with using holes in ribs compared with that of the solid one. The reason for the increase in heat transfer is due to an increase in turbulence and thermal surface area. Moreover, it is observed changing shapes of the perforated ribs affect the parameters of heat transfer performance. The percentage of increase and improvement in heat transfer for solid ribs was (11.11%, 14.4%, and 12.5%) respectively. As for perforated ribs, the percentages of Nusselt number, convection coefficient, and heat transfer rate improved by (16.9%, 19.7%, and 17.2%) respectively, to a Reynolds number of 32051.

At times, due to change in design, replace in the construction design, function and general mistakes, it led to heavier or additional loads. These reason caused a brittle failure known as a punching shear of flat plates may be occur under static or dynamics load. Many works have been carried the objectives of punching shear strength presence flat slabs and the behavior of repaired flat plates damaged due to punching shear. In addition to increase thickness of slab, increase dimension of column, there are many technics focuses on slab column connection strengthened with varies way such as carbon fiber reinforced polymer, steel stiffeners, steel angle and steel collar with a view to enhancement, the punching shear strength of flat slab appears. This paper shows comparison between the slabs strengthening with these ways.

Punching shear failure is an unfavorable failure mechanism that happens abruptly with little displacement in reinforced concrete flat slabs subjected to focused stress. A localized punching failure in one column increases the shear force acting on the surrounding columns. This could cause the adjoining columns to also experience a punching failure, ultimately resulting in the progressive collapse of the entire structure. In a way akin to a chain reaction, progressive collapse is the term used to characterize the propagation of an initial local failure within a structure, which may lead to a partial or complete collapse. This paper aims to investigate the impact of steel fiber on the punching shear of lightweight slabs. Three slabs measuring 750 x 750 x 70 mm are created. Two percentage of crimped steel fiber are using the volume of steel fiber was (0.5, 1) %. The results showed It can be seen that the ultimate load capacity was increased by (47.36) and (76.05) respectively. For sample content (0.5 and 1) steel fiber compare to control slab (S1-L-W). The results showed that the use of crimped steel fiber improved the first crack load by (84, 182.9) % for slabs used crimped steel fiber. Overall, the findings of this study indicate that adding the crimped steel fibers have significantly increased the ultimate load capacity, Ductility and toughness of the tested RLWC slabs.

This study aims to develop a competitive housing model for the Iraqi housing sector, focusing on the challenges facing this sector, such as high houses price, houses low quality, and low housing competitiveness compared to international standards. This study addresses the impact of economic shifts, particularly globalization and the adoption of liberal economies, on the housing sector, emphasizing the need to invest in intellectual capital and improve architectural management to achieve sustainable competitive advantages. The research analyses key competitive indicators such as cost, quality, and financial returns, in addition to internal and external factors affecting the sector. It highlights the importance of innovation in architectural design and the use of modern technology, alongside enhancing public-private sector integration to support infrastructure and improve housing policies. By analysing Iraq's economic and social environment, the research proposes innovative strategies to boost competitiveness, including improving the quality of housing units, reducing construction costs, and fostering public-private partnerships. The study shows that achieving a balance between cost and quality, while increasing investment in intellectual capital, can enhance the competitiveness of Iraq's housing sector, contributing to better living standards and economic stability.

In this study, three laboratory samples of a nanofluid consisting of alumina in a propylene glycol solution were prepared for three different concentrations in weight ratios (0.2, 0.4, and 0.6%). The thermal conductivity and dynamic viscosity of the three concentrations were measured at different temperatures (20, 60, 100, 140, and 180) °C. The results showed that the concentration of 0.6% is the highest value for thermal conductivity, and it was chosen as a working fluid in the experimental device. The nanofluid was placed in copper tubes to act as a heat transfer fluid. Sunflower oil was used as a medium to store the heat acquired from solar radiation. The oil was placed inside the evacuated tube, and the spiral annular copper tube was immersed in the vegetable oil and the second copper tube inside the water tank. They were connected to each other with copper connectors and copper ball valves. The experimental device was operated on March 2, 2024, and the highest temperature of vegetable oil was recorded at 134.9 °C, nanofluid coming out of the water tank at 35.6 °C, nanofluid entering the water tank at 80 °C, and water temperature at 42 °C at 6 pm. The experimental device continued to operate, and on April 2, 2024, the highest temperatures of oil, outgoing liquid, incoming liquid, and water were recorded at (164.1, 62.9, 103, and 70.8) °C, respectively, at 6 pm. With the continued operation of the experimental device, there was a noticeable increase in temperatures, and the highest temperatures were recorded on May 15, 2024, for oil, outgoing liquid, incoming liquid, and water at (174.1, 69.4, 115.9, and 80) °C, respectively. At the same time, the intensity of solar radiation falling on the evacuated tube was calculated during the daytime hours from 8 am to 6 pm. The average solar radiation for one day was recorded and the amount of heat stored in sunflower oil and the amount of heat stored in water were calculated and the efficiency of the evacuated tube was calculated. The efficiency of the evacuated tube was (66%,54%,52%) For the days mentioned above.

This research studies the effect of treating sandy soil with steel slag under seismic action (El Centro, Kobe) because of the present increase in seismic effectiveness and going to minimize damage of the foundations by excessive settlement. Steel slag was added to sandy soil with three percentages (3%, 6%, and 9%) and compacted with a relative density of 56%, and 77%. The prepared soil samples were tested on a shaking table (vibrating table). Settlement occurs due to dynamic force. A circular foundation with a diameter of 100 mm and a thickness of 40 mm was used, and the applied load was constant at 3.81kg. When the earthquake accelerates more, it results in increased settlement of the circular foundation based on sandy soil, in a dry or saturated state. The settlement of the foundation increases when subjected to the El Centro and Kobe earthquakes. In addition, increasing the mixing ratios and relative density decreases the settlement of the foundation subjected to earthquake. As the mixing ratio increased to 9%, the settlement ratio decreased. In the dry state, the settlement decreased by (37.42% and 36.77%) at a relative density of 56% for the El Centro and Kobe respectively. At a relative density of 77%, the settlement rate decreased by (39.31% and 39.89%), respectively. In the saturated state, the settlement decreased by (28.05% and 22.92%) at a relative density of 56% for the El Centro and Kobe respectively. At a relative density of 77%, the settlement rate decreased by (31.87% and 25.17%) for the El Centro and Kobe respectively. The settlement for the saturated state was twice that for the dry state.