Tadesse G. WakjiraUniversity of British Columbia - Okanagan | UBC Okanagan
Tadesse G. Wakjira
Doctor of Philosophy
About
50
Publications
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Publications
Publications (50)
This paper presents an experimental study carried out on the structural performance of shear-critical reinforced concrete (RC) deep beams internally reinforced with two different stirrups configurations; i.e. aligned and unaligned with the fabric-reinforced cementitious matrix (FRCM) strips. The test matrix involved two unstrengthened (reference) b...
The use of steel reinforced grout (SRG) has emerged as a promising technique for the strengthening and retrofitting of reinforced concrete (RC) structures, however, the experimental evidence on its application for shear-critical RC beams is rather limited. Accordingly, this study focuses on the structural performance of SRG-strengthened RC beams cr...
The shear behavior of fabric reinforced cementitious matrix (FRCM) strengthened beams requires more research efforts to be fully understood. A detailed investigation into the shear capacity of FRCM shear-strengthened beams has generally been limited. Therefore, the development of an accurate and reliable mechanics-based design model is required for...
This paper presents a study on the efficacy of a shear strengthening technique utilizing fabric reinforced ce- mentitious matrix (FRCM) systems for beams with and without internal transverse shear reinforcement (ITSR) within the critical shear span (CSS). The paper focuses on the FRCM/ITSR interaction, experimentally and analytically. Three different...
The externally bonded (EB) fabric reinforced cementitious matrix (FRCM) has successfully been used as a structural strengthening for various applications including flexural and shear strengthening of reinforced concrete (RC) beams, flexural strengthening of RC slabs and column confinement. However, the EB-FRCM system is characterized by poor FRCM/c...
Executing a single Bitcoin transaction equates approximately to the greenhouse gas emissions of a moderate-sized electric or gasoline engine sedan vehicle traveling between 1600 and 2600 km. This research undertakes an examination of Bitcoin’s real climate problem and presents a novel framework and an in-depth analysis of Bitcoin mining’s carbon fo...
Stress-strain constitutive model for confined ultra-high-performance concrete (UHPC) plays a pivotal role in the design and modelling of UHPC structures. However, while extensive research exists on the stress-strain responses of unconfined UHPC, a notable dearth of studies focuses on the stress-strain constitutive model for confined UHPC. According...
This study aims to propose a novel framework for strength prediction and multi-objective optimization (MOO) of economical and environmentally sustainable ultra-high-performance concrete (UHPC) which aids in intelligent, sustainable, and resilient construction. Different tree-and boosting ensemble-based machine learning (ML) models are integrated to...
Reverse osmosis is the most popular membrane-based desalination process that accounts presently for more than half the worldwide desalination capacity. However, the complex involvement of a variety of factors in this process has hindered the efficient assessment of the process performance such as accurately determining the membrane flux. It is ther...
Steel corrosion poses a serious threat to the structural performance of reinforced concrete (RC) structures. Thus, this study evaluates the flexural capacity of RC beams through machine learning (ML)-based techniques with six parameters used as input features: beam width, beam effective depth, concrete compressive strength, reinforcement ratio, rei...
Fiber-reinforced polymer (FRP) composites are increasingly used in concrete structures owing to their superior corrosion resistance. However, FRP-reinforced concrete (RC) structures exhibit less ductile response compared to steel RC structures. Recently, the use of basalt fiber reinforced concrete (BFRC) reinforced with BFRP bars was investigated t...
The endeavors toward sustainable transportation systems are a key concern for planners and decision-makers where increasing public transport attractiveness is essential. In this paper, a machine-learning-based predictive modeling approach is proposed for metro ridership prediction, considering the built environment around the stations; it is in the...
Smart cities are centres of economic opulence and hope for standardized living. Understanding the shades of urban resilience and livability in smart city models is of paramount importance. This study presents a novel two-stage data-driven framework combining a multivariate metric-distance analysis with machine learning (ML) techniques for resilienc...
Fiber-reinforced polymer (FRP) composites have recently been considered in the field of structural engineering as one of the best alternatives to conventional steel reinforcement due to their high tensile strength, lightweight, cost-effectiveness, and superior corrosion resistance. However, the variation in FRP physical and mechanical characteristi...
This study presents a novel explainable machine learning (ML) based predictive model for the lateral cyclic response of post-tensioned (PT) base rocking steel bridge piers. The PT rocking steel bridge pier comprises a circular tube with welded circular base plate that is pre-compressed to its base by means of gravity loads and/or a PT tendon. The i...
The application of inorganic composites has proven to be an effective strengthening technique for shear-critical reinforced concrete (RC) beams. However, accurate prediction of the shear capacity of RC beams strengthened with inorganic composites has been a challenging problem due to its complex failure mechanism and the interaction between the int...
Many concrete bridges around the world have passed their service life and are at high risk of collapse, especially in active seismic regions. This is particularly true in many developing and underdeveloped countries, where deficient construction and underpreparedness would result in a major catastrophe should a major seismic event occur. Thus, ther...
Corrosion in steel reinforcement is a central issue behind the severe deterioration of existing reinforced concrete (RC) structures. Nowadays, fiber-reinforced polymer (FRP) is increasingly being used as a viable alternative to conventional steel reinforcement due to its anti-corrosive nature. The accurate estimation of the shear capacity of FRP re...
This paper presents a data-driven approach to determine the load and flexural capacities of reinforced concrete (RC) beams strengthened with fabric reinforced cementitious matrix (FRCM) composites in flexure. A total of seven machine learning (ML) models such as kernel ridge regression, K-nearest neighbors, support vector regression, classification...
Predicting metro ridership is an essential requirement for efficient metro operation and management. The dependence of metro ridership on the land use densities entails a need for an accurate predictive model. To this end, the current study is aimed to develop a novel machine learning (ML) based model to predict the metro station ridership utilizin...
It is critical to properly define the plastic hinge region (the region that is exposed to maximum plastic deformation) of reinforced concrete (RC) columns to assess their performances in terms of ductility and energy dissipation capacity, implement retrofitting techniques, and control damages under lateral loads. The plastic hinge length (PHL) is u...
Concrete bridge piers reinforced with conventional steel bars experience large permanent (residual) deformation that may lead to uneconomical repair or demotion of bridges due to their non-functionality post strong seismic event. Thus, sufficiently ductile materials are required to reinforce concrete bridge piers in the plastic hinge zone in order...
In this study, steel reinforced grout (SRG) is proposed for shear strengthening of reinforced concrete (RC) beams using the near‐surface embedded (NSE) technique. It is believed based on several research contributions in the literature that the NSE technique precludes or delays the onset of premature debonding and achieves higher strength increase...
This study explores the effects of key design parameters on the performance of seismically deficient rectangular cross-section reinforced concrete (RC) bridge piers strengthened with steel-reinforced polymer (SRP) composites. Nonlinear response of bridge piers was modeled using fiber-based section discretization. Three-level fractional factorial de...
It is vital to understand the shear behaviour of reinforced concrete (RC) beams in order to avoid a catastrophic shear failure and design for ductile failure. However, due to the complexity in the shear failure mechanism and various parameters influencing the shear behaviour of RC beams, the accuracy in the determination of the shear capacity remai...
The effect of the shear span-to-depth (a/d) ratio on the shear behavior of steel reinforced grout (SRG)-strengthened reinforced concrete (RC) beams is experimentally investigated. Four critical shear spans corresponding to a/d ratios of 1.60, 2.10, 2.60, and 3.10, representing a range for deep to slender beams were considered. In addition, the effe...
This study investigated the efficacy of near surface mounted (NSM) hybrid carbon/glass fibre reinforced polymer (FRP) strips for strengthening of shear-deficient reinforced-concrete (RC) rectangular deep beams. A specific focus was the interaction of FRP with steel stirrups, which were arranged in both aligned and unaligned configurations for diffe...
The efficacy of hybrid near-surface embedded/externally bonded (NSE/EB) fabric-reinforced cementitious matrix (FRCM) for flexural strengthening of reinforced concrete (RC) beams was assessed experimentally. Bending tests were conducted on eight RC beams: 6 strengthened and two reference beams. The test parameters were (a) the internal tensile reinf...
Steel reinforced grout (SRG) has shown to be an efficient and cost-effective strengthening solution for reinforced concrete (RC) structures. With regard to RC beams, the experimental studies to date have focused mainly on the application of SRG for flexural strengthening of RC beams, however, the study on its application for the strengthening of sh...
This paper presents experimental results on the strengthening of reinforced concrete (RC) beams using “hybrid near surface embedded/externally bonded” NSE/EB technique for fabric reinforced cementitious matrix (FRCM). Six RC beams have been constructed, strengthened in shear using the NSE/EB-FRCM system and tested in addition to one control beam wi...
Road traffic crashes (RTCs) are globally acknowledged as increasing threat to society, because they can affect many lives when they result in severe injury or fatality. In the State of Qatar RTCs are getting more awareness and attention, aiming to improve the traffic safety in the country. This study is an exploratory research providing different a...
Exiting literature revealed that fabric reinforced cementitious matrix (FRCM) is a promising material for the strengthening of shear deficient reinforced concrete (RC) beams. However, most of the available experimental studies are devoted to the use of the FRCM system for the strengthening of slender beams and limited literature is available on the...
Fabric-reinforced cementitious matrix, FRCM, system has shown to be promising for the strengthening of reinforced concrete (RC) beams. However, the available experimental investigation on the shear strengthening efficacy of FRCM system is limited, particularly for deep beams. Moreover, to the authors' knowledge, no literature is available on the ef...
In spite of the availability of different models proposed to predict the shear capacity of reinforced concrete (RC) beams strengthened in shear using fabric reinforced cementitious matrix (FRCM) system, accurately predicting this value remains a challenge. The simplified compression field theory has shown to accurately predict the shear capacity of...
This paper presents an experimental study on the flexural behaviour of RC beams strengthened with fabric reinforced cementitious matrix (FRCM) system. Eight T-shaped RC beams with two different flexural reinforcement ratios (í µí¼ í µí± =0.40% and í µí¼ í µí± =1.02%) were constructed and tested as simply supported under monotonic three-point load...
This paper presents an experimental study on the efficacy of a lately introduced "near surface embedded" technique (NSE) for fabric reinforced cementitious matrix (FRCM) for the strengthening of reinforced concrete (RC) beams in shear; considering two test variables: (a) fabric type (glass and carbon) and (b) strengthening configuration (intermitte...
The use of a recently introduced “near surface embedded” (NSE) technique for fabric reinforced cementitious matrix (FRCM) system is shown to be a viable alternative to the conventionally used externally bonded FRCM counterpart with the potential to mitigate FRCM/concrete debonding. This paper presents a study on the interaction of FRCM and stirrups...
This paper presents the efficacy of a new technique of fabric reinforced cementitious matrix (FRCM) for the strengthening of shear deficient reinforced concrete (RC) beams. This technique involves embedding the FRCM composites in the concrete cover and is referred to as “near surface embedded” FRCM (NSE-FRCM) technique. Five (5) medium scale rectan...
This paper presents an experimental study on the efficacy of a recently introduced hybrid "near surface embedded/ externally bonded" NSE/EB fabric reinforced cementitious matrix (FRCM). Seven medium scale RC beams, deficient in shear, were constructed and tested under three-point loading. Six beams were strengthened using hybrid NSE/EB-FRCM techniq...
This thesis presents an experimental study on the efficacy of new concepts of strengthening reinforced concrete beams deficient in shear. The first concept is referred to as “near surface embedded” fabric reinforced cementitious matrix (NSE-FRCM). The interaction between the transverse shear reinforcement (TSR) and NSE-FRCM system has been investig...
Questions
Question (1)
The capacity of the strut and node in the STM depends on the dimensions of the support and loading plates; however, these values are not provided in most of the literature.