Zede Journal of Ethiopian Engineers and Architects

Analytical Hierarchy Process Model for Selecting Road Contractors: A Case of Ethiopian Roads Administration

2025-12-20T05:52:53+00:00

In the construction industry, the successful completion of a project mainly depends on the performance and capability of the contractor. It is therefore understood that the success of a project may be compromised without an appropriate and reliable process for identifying the most suitable contractor. Commonly, many organizations select contractors primarily on the lowest bid offer, as it is simple and emphasizes cost efficiency. However, this approach often undermines other important factors. Hence, incorporating a multi criteria decision making approach ensures a more balanced evaluation that considers both bid price and other key criteria. This study explores the application of the Analytical Hierarchy Process as a decision-making model for contractor’s selection. A combination of descriptive and case study research design was employed to identify and prioritize the contractor selection criteria. An extensive literature review identified 23 contractor selection criteria, which were categorized into four main groups. A structured questionnaire was then used to collect primary data based on these criteria. Once the data is gathered, the criteria are ranked in order of significance and prioritized for use in the analytical hierarchy process model. The analysis revealed that past performance competency had the highest weight (38.56%) with a consistency ratio of 0.088, followed by technical competency (24.16%) and financial competency (20.42%). Management competency ranked lowest at 16.84%, with a consistency ratio of 0.0529. In summary,the proposed model enhances the contractor selection process by integrating multiple key competencies to evaluate contractors across broader criteria.

Safety Evaluation of Reinforced Concrete Highway Bridges Under Overloaded Truck Traffic: A Data-driven Assessment using Static Weighing Station (sws) Records

2025-12-20T05:54:40+00:00

Assessing performance assessment of reinforced concrete (RC) highway bridges subjected to overloaded truck is important in maintaining safety and sustainability of transport infrastructures. These trucks cause threat to bridges and lead to deterioration if not managed. The framework of assessment consists of structural analysis techniques, load rating methodologies, condition assessment procedures, and risk evaluation criteria. Studies showed that bridges in Ethiopia are overloaded and hence, in this study, a comprehensive safety assessment of selected RC highway bridges subjected to overloaded truck is presented. Nine RC girder bridges found along the selected routes have been considered for investigation. To investigate the effects of overloaded vehicles on Ethiopian bridges, 51,900 actual truck loading data from three static weighing stations (SWS) were collected over a period of five years. Rating factors for bridges were determined based on legal loads, actual truck load data, and extrapolated load data, taking into account the estimated remaining service life of the bridges and possible future reinforcement corrosion. The results revealed that, on average, 16.3 % and 33.85 % of the trucks violated the limit set on national regulation and bridge formulas, respectively. In addition, the rating factors for the bridges were reduced by 30.18 % and 56.29 % for the actual truck load data and extrapolated load data, respectively, compared to the legal loads. The result showed the bridges’ performance is severely affected and hence enforcing the current law and developing appropriate mitigation strategies are recommended.

Experimental Study on the Efficiency of Passive Auto-tuning Compound Pendulum Mass Damper

2025-12-20T05:55:55+00:00

A Tuned Mass Damper (TMD) is a device used to reduce the effects of dynamic responses of a structure during seismic action. In this study, a test model of a two-story steel structure was used to evaluate the efficiency of the Passive Auto-Tuning Compound Pendulum Mass Damper (PATCPMD). The PATCPMDs were suspended in the structure's top and lower stories and controlled by a group of flexible ropes that formed a compound pendulum, but it was not quite a compound pendulum and could move in any translational direction. The results showed that use of PATCPMD can provide significant control over the structure's translational, torsional, and coupled vibrations, with a maximum reduction in peak SSMS of 75 % for translational vibrations and up to 65 % for torsional vibrations when they are suspended in the first story. These values increased to 90 % for translational and 87 % for torsional vibrations when suspending in the second story. For forced vibrations, the maximum reductions in vibration control achieved were 68 % and 89 % if the damper was suspended in the first and second floor levels, respectively. Results showed that using PATCMD is more efficient when suspended on the second floor.

Base Isolation for Earthquake Protection of Structures Considering Ethiopian Standard

2025-12-20T05:56:52+00:00

An increase in construction activities and recent advances in structural engineering necessitated the major revision of the Ethiopian Building Code Standard (EBCS), published in 1995. The updated building code has introduced improved earthquake-resistant design considerations, including provisions for base-isolated (BI) structures. This study investigates the efficacy of the base isolation technique in earthquake protection of buildings considering Ethiopian standard. Moreover, the validity of the specific provisions of the Ethiopian seismic standard, i.e., Ethiopian Standard European Norm, (ES EN 1998-1:2015) on the choice of base isolator properties for analysis and design is investigated. Non-linear dynamic response history analyses of multi-story BI buildings are performed under synthetic earthquakes, matching with the response spectrum of the Ethiopian standard. Furthermore, the vibration response of fixed-base building models is reported for comparison. Four structural response quantities, i.e., the floor acceleration, base shear, inter-story drift, and isolator displacement, are studied. The findings demonstrate that the application of the base isolation technique reduces the dynamic response of multi-story buildings substantially. In addition, it is shown that some of the Ethiopian seismic standard provisions on isolator parameter consideration are not in logical agreement with the earthquake behavior of BI buildings observed in the current study.

Investigation of the Effect of Lime Treatment on the Soil Water characteristics curve of expansive Soils

2025-12-20T05:57:46+00:00

The engineering behavior of natural untreated and compacted lime-treated expansive soils, which typically exist in a state of unsaturated condition, can be better-explained using concepts from unsaturated soil mechanics. The soil water characteristics curve (SWCC) is the key unsaturated soil property for obtaining unsaturated soil property functions (USPFs). However, there are limited studies on the effect of lime on the SWCC of lime-treated expansive soils. This study investigated the effect of lime on the SWCC of lime-treated expansive soils. The drying portion of SWCCs for untreated natural soil and lime - treated soil samples with three different lime contents (3 %, 6 % and 9 %) with 7 days of curing were studied. The SWCCs were determined by using pressure plate apparatus in the suction range of 0 – 1400 kPa. The shrinkage curve (SC) was also determined to evaluate the change in volume of the different soil samples. The experimental results indicate that SWCC is affected by lime treatment and there is a change in the SWCC parameters and in the shape and position of SWCC as the percentage of lime is changed. The SWCC of the lime-treated soil samples show a higher rate of desaturation as the lime content increases. The Air Entry Value (AEV) and residual water content of lime-treated soil decreases with increase in percentage of lime and the SWCC shifts towards the left side as the AEV decreases. The differences in AEV obtained from gravimetric- water-content-based SWCC (w-SWCC) and degree-of-saturation-based SWCC (S-SWCC) for the lime-treated soil samples were small when compared to the untreated natural soil sample.
Keywords: Air-entry value, Expansive soil, Lime treatment, Shrinkage curve, Soil–water characteristic curve, Unsaturated soil.

Spectrum Occupancy Predictions Using Deep Learning Algorithms

2025-12-20T05:58:53+00:00

The fixed spectrum allocation (FSA) policy causes a waste of valuable and limited natural resources because a significant portion of the spectrum allocated to users is unused. With the exponential growth of wireless devices and the continuous development of new technologies demanding more bandwidth, there is a significant spectrum shortage under current policies. Dynamic spectrum access (DSA) implemented in a cognitive radio network (CRN) is an emerging solution to meet the growing demand for spectrum that promises to improve spectrum utilization, enabling secondary users (SUs) to utilize unused spectrum allocated to primary users (PUs). This study has addressed all the limitations of the previous studies by implementing a comprehensive approach that encompasses reliable spectrum sensing, potential candidate spectrum band identification, long-term adaptive prediction modeling, and quantification of improvements achieved in the prediction model. The Long-Short Term Memory (LSTM) Deep Learning (DL) model was proposed as a solution for this study to address the challenge of capturing temporal dynamics in sequential inputs. The LSTM model leverages a gating mechanism to regulate information flow within the network, allowing it to learn and model long-term temporal dependencies effectively. The dataset used for this study was obtained from a real-world spectrum measurement by employing the Cyclostationary Feature Detection (CFD) approaches in the GSM900 mobile network uplink band, spanning a frequency range of 902.5 to 915 MHz over five consecutive days. The dataset comprises a total of 225,000 data points. The five-day spectrum measurement data analysis yielded an average spectrum utilization of 20.47 %. The proposed model predicted the spectrum occupancy state for 5 hours ahead in the future with an accuracy of 99.45 %, improved the spectrum utilization from 20.47 % to 98.28 % and reduced the sensing energy to 29.39 % compared to real-time sensing.

Image Deblurring with Compressive Sensing

2025-12-20T05:59:56+00:00

Compressive sensing is a technique that enables recovery of signals represented by an underdetermined system of equations. Such a recovery of an original signal is made possible if the samples are represented in a sparse manner provided an appropriate measuring matrix is used for the modelled system. Blurred images are examples of signals that are sparse especially in transform domains. Different researches have been done to show the possibility of recovering blurred images that use sparse representation of transform domains by applying compressive sensing. In our work, however, we propose a model that doesn’t require transforming into other domains. In addition, a box-wise approach has been used that derives the underdetermined system matrix from 7x7 segmented boxes of the blurred image. Compressive sensing algorithms are applied on these boxes to recover the whole image iteratively. Our method is shown to have a much better computational complexity than the traditional Lucy-Richardson deblurring method. Thus, with this improved computational complexity, the study provides an initial platform to deblur images using box-wise method and compressive sensing technique.

Enhanced Mechanical properties Characterization of General Purpose Unsaturated Polyester Resin using Nano Cellulose Particles: Industrial Application.

2025-12-20T06:01:06+00:00

Though the unsaturated polyester resin is highly versatile with a wide range of application, its low impact strength, low elongation at break and low toughness constrain its applications. In this article, study of an unsaturated polymer resin was conducted by adding optimum amount of nanocellulose fillers extracted from sugarcane bagasse. Mechanical and microstructural properties were characterized by testing the composite with 0.5 %, 1 %, 2 %, and 3 % fiber weight fraction of the nanocellulose. Mechanical properties such as tensile, compression, impact, flexural, as well as X-ray powder diffraction, Fourier Transform Infrared Spectroscopy (FTIR), and thermo gravimetric analysis (TGA) were performed. The results indicate that 10 nm particle size and 2 % nanocellulose by weight fraction is best, which gives enhanced mechanical properties of the composite material up to 45 % tensile strength, 38 % flexural strength, 13 % compression strength and 8 % impact strength improvement. The composite material also shows improved thermal stability and bond stretching due to the incorporation of nanocellulose particles.

Performance evaluation of modified solar bubble dryer for red pepper (capsicum)

2025-12-20T06:01:54+00:00

Effect of Thermal Annealing on Device Performance of Organic and Solid- State Dye-sensitized Photovoltaics

2025-12-20T06:02:50+00:00