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SEISMIC PERFORMANCE EVALUATION OF REINFORCED HCB FULLY GROUTED MASONRY WALLS AND ITS PERFORMANCE COMPARING WITH UNREINFORCED FULLY GROUTED MASONRY WALLS
(Hawassa University, 2021-10-22) ZERIHUN TALE BIZUNEH
A reinforced hollow concrete block masonry walls constructed by assembling masonry
units, and it was the key structural element widely used to resist lateral loads in masonry
buildings. Unreinforced hollow concrete block Masonry wall rapidly fails because of
lateral load like an earthquake. Hence this study attempts to evaluate responses of a
reinforced and unreinforced fully grouted hollow concrete block masonry wall, select the
best walls based on differing their aspect (H/L) ratio, horizontal and vertical
reinforcement ratio, and spacing. Also, know the behavior of reinforced and unreinforced
fully grouted hollow concrete block masonry wall under lateral load and determine its
percentage effectiveness. The study was conducted using finite element ABAQUS software
for which a total of 24 masonry wall models were considered. For validation of the finite
element method, reinforced masonry walls experimentally worked by M. Hany (2016), and
the experimental results compared with the numerically modeled. The comparison of the
results indicated that both experimental and numerical results agreed very well. After the
validation, the effect of seismic load on reinforced and unreinforced fully grouted hollow
concrete block masonry walls investigated by the quasi-static method. The comparison for
ultimate load carrying capacity, stiffness degradation, and displacement ductility of each
investigation parameter are carried out from the comparative analysis. It was found that
the aspect ratio 1.39 wall vertical reinforcement ratio increases from 0.26% to 0.36%, the
ultimate strength increase by 15.344% for push and 14.578% for pull direction. And also,
the vertical reinforcement spacing increases the Ultimate strength of the wall decrease.
The Ultimate shear resistance of the wall is reduced by 17.21% for push and 14.25% for
pull direction for in-plane load when the spacing of Ø16 vertical reinforcement increases
from 200mm to 400mm. The aspect H/L ratio increase from 1.39 to 1.95 the ultimate
strength decrease by 38.15% for push direction and 41.89% for pull direction. Generally,
aspect ratio, vertical reinforcement spacing, and vertical reinforcement ratio variation
highly influence hollow concrete masonry wall seismic performance relative to horizontal
reinforcement
EVALUATION OF MICRO AND SMALL ENTERPRISES PERFORMANCE IN 20/80 CONDOMINUM HOUSING CONSTRUCTION: THE CASE OF GULELE SUB-CITY, ADDIS ABABA
(Hawassa University, 2019-10-17) ZERIHUN ALEMAYEHU TEKA
Ethiopia has embarked on a long term development strategy which aimed at achieving
sustainable development with all pre-requisites for a middle income country by the year 2025.
The poor and deteriorated state of the construction industry with poor performance has
detrimental effects to the developments of the industry. Thus, makes construction industry end
product encountered many problems in terms of quality, delivery time and cost. Therefore the
aims of this study also evaluation on micro and small enterprises that were engaged in 20/80
condominium housing construction at Addis Ababa in terms of quality, delivery time and cost.
To achieve the proposed objectives, data were collected through the case study; questionnaire
survey and site observation then making detailed discussion and analysis of problems and
constraints that were hampering the performance of them. The finding of this research
indicates MSEs on the average 67.6% MSEs couldn‟t delivered their activities on the required
time, 75.7% MSEs couldn‟t deliver quality product output and 54.05% housing construction
project office saves its cost by participating MSEs than that of contractors. On the other hand,
on average according to the respondent 78.37% critical challenges were that hamper the
performances of MSEs in 20/80 condominium housing construction projects at Addis Ababa.
Factors causing delay in delivery of activities for MSEs are: delay in delivery of materials,
contractor improper planning and skill shortage whereas factors which affect their quality
include poor project management, low quality of materials and lack of experience. On the
other hand major factors that cause cost overrun for MSEs in rendering activities are delay in
material supply, poor project management and lack of skill. This study contributes to the
advance knowledge in the area of enhancing and improving the performance of micro and
small enterprises on 20/80 condominium housing construction. And also, its output will be
used as a primary input for the government body during amendment and introducing of the
new policies on the issues like, challenges that hampers the performance of MSEs and the
solutions to overcome those problems
MULTIVARIATE COMPARATIVE ANALYSIS FOR SELECTION OF INTERSECTION CONTROL (CASE STUDY FOR SELECTED UNCONTROLLED INTERSECTIONS IN HAWASSA CITY
(Hawassa University, 2019-08-12) ZEMENAYHU BORENA BORSAMO
Uncontrolled intersections that are found on major road carrying a higher traffic volume
generally have traffic safety and operational problems. This is due to the crossing and
turning movements at this intersection cannot be satisfactorily managed with existing
uncontrolled intersection. At major arterial road intersection with medium and high
volume roads where grade separation can‟t be justified traffic would generally be
controlled by either signal or roundabouts. The main objective of this thesis is to assess
and find out optimum intersection control mechanism from roundabout or signalized
intersection for existing uncontrolled intersection of shell and Addisu Menhariya in
Hawassa city. These intersections are selected because both are found on major road
carrying high traffic volumes (AADT) that justify the introduction of roundabout or
signalized intersection based on ERA intersection selection criteria. The methodology
that is used for selection is multivariate comparative analysis that uses cost, operational
performance and safety performance as evaluation criteria. The traffic, geometric, cost,
signal and crash data‟s are collected to make Comparison. Operational performance
analyses are made using HCM 2010 methodologies incorporated in SIDRA Intersection
software 5.1.The safety performances are measured using mean crash rates and
causalities for similar intersection types for years from 2014 to 2018 G.C for millions of
entering vehicles to intersections. The costs that are used for comparison are estimated
initial costs for alternatives based on current market prices of the city and operational
costs that are found using SIDRA Intersection software 5.1.The result show that proposed
roundabout and signal intersections will serve LOS C and LOC F with existing traffic
condition in both intersections respectively. The summary data indicates that the casualty
crash exposure rate at roundabouts in Hawassa city is approximately 19% less than the
casualty crash exposure rate of signalized intersections, when averaged across all crash
types. The fuel costs and operational cost for roundabout intersection are also lesser than
alternative signalized intersection. But the initial cost for roundabout is higher than
proposed signalized intersection. Roundabout options are finally recommended for
existing uncontrolled intersections of shell and Addisu Menhariya in Hawassa city
UTILIZATION OF BASALTIC QUARRY DUST AS A PARTIAL REPLACEMENT OF CEMENT IN HOLLOW CONCRETE BLOCK PRODUCTION IN THE CITY OF ADDIS ABABA (THE CASE OF KALITY AGGREGATE PRODUCTION SITE)
(Hawassa University, 2019-10-16) YOHANNIS LEMMA ALEMU
Crusher dust is a byproduct from crushing of coarse aggregate during quarrying activities.
The utilization of this materials as a manufactured sand is controversial due to excessive fine
particles in it and the disposal of fine materials is causing environmental problem. On other
hand, the use of hollow concrete blocks as a walling material has been increased following
the boosting of building construction activity in the country. This resulted in shortage of
construction materials, especially the cement, creating price escalation. Furthermore, the
sustainability problem related with the production of cement is a major issue of the globe.
This research was, therefore, conducted to examine the potential of basaltic crusher dust as
partial replacement for Portland pozzolana cement in hollow concrete block production. In
doing so, Some units of cement pastes and concrete hollow blocks of different classes, i.e.
A, B and C, were produced by partially replacing the cement content with 10%, 20%, 30%
and 40% by weight of basaltic crusher dust using vibrating block molding machine. The
units without basaltic crusher dust serve as a control. The cement pastes were examined for
consistency and setting time, and the blocks produced were tested to determine their
compressive strength, water absorption rate and density. Furthermore, the possible cost
advantages of using basaltic crusher dust as partial replacement of cement in hollow concrete
block were analyzed. The result indicates that the experimental HCB of class A and C
surpassed the required standard of compressive strength, water absorption and density
specified by the Ethiopian standard ES 596:2001; whereas, the compressive strength of class
B fails at 40% cement replacement. It was concluded that concrete hollow blocks of class A
and C with up to 40% replacement and class B with up to 30% replacement can be used for
load bearing walls and save costs of block with comparable properties
NEGATIVE ENVIRONMENTAL IMPACTS OF CONSTRUCTION ACTIVITIES IN SNNPRS: (THE CASE OF BUILDING CONSTRUCTION PROJECTS IN SELECTED TOWNS
(Hawassa University, 2019-10-10) YIDNEKACHEW ESAYAS
Construction activities affect the environment throughout the life cycle of development.
Even though the construction period is comparatively shorter in relation to the other stages
of a building’s life, it has diverse significant effects on the environment. This study was
carried out to identify the major environmental impacts of construction activities on building
construction projects of selected towns in SNNPRS and to propose measures for their
mitigation. Eleven site activities adversely affecting the environment; thirty-three possible
environmental impacts of construction activities; and four groups of people likely to be
affected by construction site activities were identified from literature. The 33 impacts were
further categorized into nine major groups. The main approaches used in collecting data for
the study were through questionnaire survey, and personal observations of some major
construction sites in selected towns. Questionnaires were distributed to a total of 174
purposively selected respondents consisting of 58 contractors, 58 consultants and 58 nearby
residents on 58 active building construction projects in selected towns. The respondents
were asked to identify the most important item from the listed. The relative importance of
the items identified were calculated and ranked by the relative importance index. According
to the results of the study, the respondents agreed that concrete vibration; concrete batching,
mixing and placement; and excavation are the main site activities having adverse
environmental impacts in selected towns. Also resource consumption group impacts ranked
highest among the major environmental impacts of construction activities in selected towns.
The resource consumption group impacts were raw materials consumption, electricity
consumption, water consumption and fuel consumption. Local issues impacts was second
followed by transport issues impacts. Noise and vibration generation from local issues
impacts group was ranked highest of all environmental impacts of construction activities.
The respondents also agreed that site workers, nearby residents, and people in schools and
hospitals are most likely to be adversely affected by construction site activities. The results
of this study will be useful to support the implementation of environmental management
systems in construction companies by providing guidance for construction practitioners.
The paper recommends that stakeholders in the construction industry should start working
with new methods and technologies following sustainable construction techniques to reduce
environmental impacts