Journal of Engineering

This paper presents a dynamic investigation of strip, rectangular, and square machine foundations on the top surface of two-layer dry sand with various states (loose on medium sand and dense on medium sand). The investigation was performed numerically using finite element programming, PLAXIS 3D. The soil was modeled as a versatile totally plastic material complying with the Mohr-Coulomb yield criterion. A harmonic load with an amplitude of 6 kPa at frequencies of 2 and 6 Hz was applied at the base, and seismic loading was applied with acceleration-time input from an earthquake in Halabjah city, north of Iraq. The study evaluated the influence of changing L/B ratio (Length=12, 6, 3 m and width=3 m), type of sand, and frequency of the machine for soil with two layers (dense and medium sand) and (loose and medium sand). Results showed that displacement decreases when the foundation is strip-shaped and is highest when the foundation is square-shaped. The maximum vertical stress of the foundation (L/B = 4 and L/B = 1) was found to be 1262 kPa and 1255 kPa, respectively. Additionally, vertical displacement increased by 20% when the relative density decreased, and displacement decreased when the frequency value changed from 2 to 6 Hz.

This study evaluates the Elaj Irrigation Project in Babil Governorate, focusing on its suitability, adequacy, and efficiency. The project relies on irrigation from Shatt Al-Hilla, and three fields (B 1, B 2, and B 3) were selected for evaluation. Field measurements of water contents before and after watering during the growing season were taken, along with root zone measurements. The study calculated application efficiency, conveyance efficiency, distribution efficiency, storage efficiency, water productivity efficiency, and water use efficiency. The application efficiency ranged between 33-39% for the selected fields, with an overall scheme efficiency of 32.3%. The study suggests improvements to the irrigation system to enhance efficiency.

This paper investigates the causes influencing the occurrence of variation orders in building construction projects. The study identifies critical factors from the perspectives of owners, contractors, and consultants through field surveys and expert interviews. The main causes include financial difficulties, changes in material specifications, technical necessities, and site conditions. The research highlights the need for better project management to reduce variation orders and improve construction efficiency.

This research focuses on producing environmentally friendly load-bearing concrete masonry units (blocks) using green concrete containing recycled plastic waste and nano silica sand powder. Five concrete mixtures were tested, with cement content ranging from 200 kg/m³ to 400 kg/m³. The mixtures included 10% plastic waste replacing coarse aggregate and varying amounts of nano silica sand powder. The compressive strength of the blocks was measured at 14 and 28 days, showing improvements with the addition of nano silica sand powder. The study demonstrates the potential of using recycled materials to produce sustainable construction materials.

This study investigates the mechanical integrity of printed circuit heat exchangers (PCHEs), which are plate-type heat exchangers known for their high performance and compact size. The research focuses on the diffusion bonding process used to join the plates, performed under specific conditions of high temperature (up to 700°C), high pressure (3.45 MPa), and an inert environment (argon gas). Tensile samples were tested to evaluate their strength, showing that diffusion-bonded specimens achieved higher tensile strength than the yield strength of copper. The study also tested a prototype heat exchanger for compressive strength, which withstood air pressure up to 8 bar and hydraulic pressure up to 60 bar before failure. The results highlight the importance of bonding techniques in ensuring the mechanical integrity of PCHEs.

This paper presents an experimental study on the bond strength between reinforcing bars and rubberized concrete, where waste tire rubber replaces natural aggregates. The study examined various factors such as rebar size, embedded length, concrete cover, yield stress of rebar, and concrete compressive strength1. The results showed a 19% reduction in bond strength for rubberized concrete with 50% rubber replacement compared to conventional concrete. The bond strength increased with higher concrete cover, compressive strength, and yield stress of rebar, while it decreased with longer embedded rebar length and larger rebar size1. The failure modes observed were push-out and splitting failures.
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