Conference Proceedings Civil Engineering 2018

FINITE ELEMENT STUDIES OF PRE-CRACKED REINFORCED CONCRETE (RC) BEAMS WITH OPENINGS STRENGTHENED BY STEEL PLATE

2021-08-26T09:16:33+00:00

In this study, a repairing of preloaded RC beams with openings strengthened with steel plate was studied by using finite
element package ANSYS14.5. To ensure that the elements, convergence criteria, and material properties are adequate
to model the behavior of the RC beam and to ensure that the simulation process is correct, the FE ANSYS was calibrated
with published experimental data. The effect of pre-damage level and loading mechanism were considered as main
parameters. Furthermore, birth and death technique was used to model the cracks before strengthening stage. In this
technique, loading was first applied till the objective cracking, followed by steel plate application, and then the load
was continued to failure. The result showed that pre-damage levels and the steel plate strengthening have a great effect
on the failure mode and ultimate load of RC beam. In addition, the results showed good agreement with those obtained
from published experimental tests. Based on FE using ANSYS an ACI guideline, an analytical equation for predicting
the shear capacity of RC beams with openings strengthened by steel plate under sustained load was then proposed.

RESEARCH INTO UNSATURATED SOIL MECHANICS AT THE UNIVERSITY OF PRETORIA

2021-08-29T08:18:00+00:00

Traditionally soil mechanics courses forming part of most civil engineering programs around the world include an introduction of the theory and principles of saturated soil mechanics. This may be perfectly adequate in many parts of the world where the water table is shallow and soil comprise a mixture of solid particles and water. However, in the African context the water table is often at significant depth, resulting in the majority of soils occurring in an unsaturated state where interaction between all three matter phases, i.e. solids (soil grains), liquids (pore water) and gases (air) are important. The resulting interaction is significantly more complex than under saturated conditions and has resulted in the development of the field of unsaturated soil mechanics.
The lecture will present research work carried out in the field of unsaturated soil mechanics at the University of Pretoria focusing on a number of practical applications as follows:
One of the most important and most difficult parameters to measure in the case of unsaturated soil is the negative water pressure in the pore water in unsaturated soil. Methods of negative pore water measurement will be reviewed and the development of a low-cost high capacity tensiometer at the University of Pretoria will be presented. This will be followed by an overview of the use of fibre optic instrumentation as a means of water leak detection from conduits in unsaturated soils. Finally, the lecture will present research work modelling unsaturated expansive soils by means of physical models in the geotechnical centrifuge at the University of Pretoria. An example from a model study considering piled foundations in expansive soils will be presented.
The presentation will emphasis the need to consider unsaturated soil behavior and will make recommendations on how
the subject could be introduced in civil engineering programs at African universities

PROPERTIES OF SUDANESE MANUFACTURED ORDINARY PORTLAND CEMENTS

2021-08-29T08:12:33+00:00

This study compares properties of six locally produced ordinary Portland cement brands in the Sudan using Analysis of Variance (ANOVA). It investigates their compliance with Sudanese and European standards. Furthermore, to examine consumers’ claims that certain brands outperforming others. Chemical, physical and mechanical cement properties have been collected from Quality Control Unit (QCU) of each factory. Also samples have been collected from local dealers for each factory and tested for same aforementioned properties. It has been observed that all brands comply with the Sudanese and European specifications for ordinary 42.5N Portland cement with regard to levels of chemical oxides, fineness & initial setting time. However, for compressive strength, according to both standards, three brands are classified as 42.5N, while the other are 42.5R, which should not be used in hot climates. However, one brand could also be dually classified as rapid hardening cement 42.5R or ordinary Portland cement 52.5N by the European Standard. The ANOVA has shown significant differences between these brands especially in compressive strength hence supporting preferences of consumers to certain brands

POZZOLANICITY ASSESSMENT OF SUDANESE GROUNDNUT SHELL ASH

2021-08-29T08:00:28+00:00

This paper focused on the evaluation of the Pozzolanic characteristics of the Sudanese Groundnut Shell Ash (GSA).
The study investigated the chemical, physical, and mineralogical characteristics of the GSA and its reactivity toward lime and cement, in addition, the compressive strengths of blended mortar containing GSA in percentage addition were tested at 7, 28, and 91 days. XRD technique was used to achieve an optimal calcining temperature for the shell. The results of the chemical analysis showed that the sum of Silica, Alumina, and Iron oxide was 83.75%. The strength reactivity with lime was 3.7MPa, against 4 MPa required by ASTM C-618 and IS: 1344. The strength activity index was found to be 73% against 75% and 80% required by ASTM C-618 and IS: 1344, respectively. These results indicated that the GSA possesses low Pozzolanic activity and the optimum pyroprocessing temperature is 650 0C with heating time 2 hours , and the recommended substitution level is 15%

POST BLAST DAMAGE EVALUATION OF RC BUILDING

2021-08-29T07:53:17+00:00

Since 2011, many civilian buildings in Arabian Countries exposed to damages due to explosion forces which have been for long time especially related to the military important. But today more important trend shall be taken towards such
type of extreme load. The importance shall not only considered the design of the buildings to resist the blast loading but also damaged building after the explosion shall be evaluated for usability and safety as soon as possible. The purpose of this study is to develop a methodology for post-blast damage evaluations and safety assessment of reinforced concrete building. To meet this goal and due similar characteristics of the Blast and Seismic loadings, comparison study has been conducted. The post-earthquake damage evaluation methodologies have been adapted and modified for postexplosion damage.

ON SITE QUALITY ASSESSMENT OF BUILDING PROJECTS IN KHARTOUM, SUDAN

2021-08-29T07:45:58+00:00

The issues of the quality of the building has been given emphasis in the construction industry apart from the problems related to cost and time. There are many disputes occurring between owners and contractors in the construction project in Sudan. Level of quality for completed works is one of the most important reasons that leads to dispute between parties. The aim of this study is to assess the level of quality of construction projects in Sudan. This study focus on building projects carried out within the area of Khartoum, Sudan. A total of 80 questionnaires were distributed to the respondents and 50 questionnaires were returned answered. The data is analyzed using Average Index. It was found that there are many ways to assess level of quality in construction projects namely by CONQUAS, QLASSIC and PASS. However, in Sudan there is no standard for the specification and it depends mainly on the companies’ experience.

MODELLING THE CORROSION AT LAP SPLICE JOINTS IN CONCRETE BEAMS

2021-08-29T07:37:15+00:00

Three-dimensional chemo-hygro-thermo-mechanical finite element model was developed to simulate the accelerated corrosion in lap splice joints in concrete. The model is used to understand non-mechanical properties such as corrosion
current intensity and corrosion expansion at the lap splice joint in addition to the mechanical properties such as corrosion cracking and crack propagation at different corrosion levels. Good agreement was found between the model
results of the pattern in concrete surface and previous experimental results from the literature

MECHANICAL PROPERTIES OF HIGH-PERFORMANCE CONCRETE PRODUCED IN SUDAN

2021-08-26T12:48:01+00:00

High Performance Concrete (HPC) is widely used in construction industry worldwide. This paper is aim to produce HPC in Sudan, using materials which are available at local markets. Different trial mixes are used to obtain a
compressive strength exceeding 80 MPa. Research includes use of mineral admixture (silica fume) and Aggregates(Crushed stone and quartz sand).
Effect of different level of silica fume replacement of cement by 0, 15, 20 and 30% on main properties of HPC, i.e., compressive strength, density and slump were investigated. Test results revealed that it is possible to produce HPC in
Sudan, with compressive strength in excess of 80 MPa using materials which are available at local markets, if carefully selected and mixed in such a way as to give optimum distribution of granules. Optimum percentage of silica fume
necessary for producing HPC is about 20 % of cement weigh.

MECHANICAL PROPERTIES OF FIBRE-REINFORCED MUD BRICKS

2021-08-26T11:48:14+00:00

Earth construction has been successfully practiced for millennia in many parts of the world, including Sudan. The authors believe that this form of construction can be readily upgraded, and that it represents a sustainable, viable alternative that avoids the use of energy intensive, high carbon content materials. This study investigates the response of fibre-reinforced mud bricks under loading. The fibre sources investigated include chicken feathers and sugarcane bagasse. Extensive compression tests were carried out on representative brick samples incorporating these materials
for the purpose of understanding the effect of fibre content on the properties of modified mud bricks. Three empiricallyderived relations for different fibre types are proposed. These relations include stress-strain curves that take into account limit state and compressive strengths for fibre-reinforced mud bricks, plus empirical correlation between the brick strength, brick density and fibre content, to be used in future design procedures. The developed relations are suitable for use in commercially available finite element software packages such as ABAQUS. The findings presented demonstrate that sugarcane bagasse and chicken feathers fibres are feasible options for mud brick reinforcement.

LOW-COST FERROCEMENT COMPOSITE ROOF/FLOOR SYSTEM

2021-08-26T11:29:37+00:00

This paper, is a part of continuous research, aims to examine the suitability of cast-in-place Ferro cement composite slab as a roof/floor system. The continuous study is mainly based on experimentation. Ferro cement is a combination of cement/sand (1:2.5) mortar, having a compressive strength higher than 30 N/mm², and expanded metal with R6mm
bars, can be utilized in any form and shape not more than 50mm thick. Two panels each consist of a 50mm slab casted over corrugated zinc sheet of 1.0m width and 4.5m length supported by central two rectangle steel pipes spaced 50cm along the long side. The pipes were connected to the panels by self –drill screws and shear keys. Steel pipes were
(120mmx50mmx1.8mm) and (100mmx50mmx1.8mm) for each panel A and B respectively. For cast-in-place
technique, the whole floor will be casted in a single day, whereas, precast panels require forms and handling effort.
Panels were tested using 50kg cement bags as a uniform distributed load. The experimental results show that panels have enough strength and can be used within the allowable service deflection limit, as a roof/floor system.

LOAD RATING OF SALVATION BRIDGE OVER THE WHITE NILE IN KHARTOUM, SUDAN

2021-08-26T10:30:17+00:00

This paper tackles load rating process on one of the most important bridges in Sudan, which is the Salvation Bridge
over the White Nile in Khartoum. The paper reviewed the main load rating types adopted by AASHTO standards.
Design load ratings have been made with respect to AASHTO-LFRD highway live loads. Legal load rating process has
been made using the Sudanese legal loads adopted by National Highway Authority in Sudan. Permit load rating process
has been made using actual special heavy truck used in Sudan during the last 20 years .The rating process has been
made on the assumption that the capacity of the main structural element of the bridge, which is the pre-stressed concrete
box girder, had been decreased with different percentage from zero up to 50%, due to different factors. Suitable
software, CSi Bridge, has been used for calculations and the results are presented. The paper predicted the load rating
factors for the box girder of the bridge- moment wise- for considerable capacity loss in future and suggested several
recommendations to save such vital structure

INVESTIGATION OF CRUSHED RED BRICKS AS LIGHT WEIGHT AGGREGATES IN CONCRETE

2021-08-26T10:13:07+00:00

Lightweight aggregate is a type of coarse aggregate that is used in the production of lightweight concrete products such
as concrete block, structural concrete, and pavement [1]. Most lightweight aggregate is produced from materials such
as clay, or shale. Blast furnace slag, natural pumice, vermiculite, and perlite can be used as substitutes; however, the
light weight aggregate has properties similar to natural aggregate, but it produces less dense and therefore yields a
lighter concrete product. The self-weight of normal concrete is estimated by more than 75% of the total dead load and
more than 50% of the total load of the structure [2]. So the use of light weight concrete will reduce the total load of
structure as well as the design cost. It can also be used in concrete block to reduce the self-weight of partition walls.
Sample of waste traditional red bricks has been crushed to the normal sizes of aggregate particles similar to natural
aggregate used. Then same mixes design are prepared for normal and crushed bricks aggregate to detect and compare
the weigh and properties of fresh and hardened concrete. The results have showed that the weight of concrete reduced
by 26%, that is mean one quarter of the normal concrete, when crushed bricks used as light weight aggregate, while
the strength is reduced by 24% at 28days. Also the workability is reduced when using light weight concrete in spite of
using saturated and surface dry crushed bricks as light weight aggregate and this may be due to angular shape and
surface texture.
It is recommended to use waste traditional red brick as crushed light weight aggregate since it reduces the self-weight
of concrete by one quarter which may suit block manufacturing as well as low strength concrete.

INFLUENCE OF ANODIC ANGLES ON CORROSION CRACK PATTERN IN REINFORCED CONCRETE

2021-08-26T09:43:36+00:00

Deterioration of reinforced concrete structures caused by chloride-induced corrosion is one of the main problems for
durability in reinforced concrete structures. Recent researches demonstrate that position and size of anodic and cathodic
angles have strong influence on crack pattern and corrosion rate and the anodic-cathodic ratios have influence on
corrosion-induced damage. All previous researches considered studying the influence of different anodic angles
numerically but no experimental investigations were found. In this paper, the influence of different anodic angles on
corrosion crack pattern and corrosion rate is investigated experimentally by applying accelerated corrosion test using
impressed voltage technique to centrally reinforced concrete cylinders with different anodic angles (360°, 180° and
60°). Current-Time relationship, percentage of steel mass loss and bond strength of the corroded samples are discussed.
The results show that the different anodic angles have strong influence on the corrosion crack pattern, corrosion rate
and bond strength. Also, it is demonstrated that the developed experimental techniques in this study can be used to
investigate the influence of different anodic angles

ADVANCES IN STRUCTURAL ENGINEERING AND EMERGING RESEARCH DIRECTIONS

2021-08-25T11:10:48+00:00

This keynote lecture presents, in general, current advances in structural engineering and outlines the future research directions in structural engineering and related fields. Specifically, it addresses recent development in strengthening and retrofitting of structures using Fiber-Reinforced Polymer (FRP) composites. It presents a review on historic and recent developments of the use of FRP and highlights some of the classic and modern experimental, numerical, and analytical studies associated with the use of FRPs in strengthening and retrofitting of Reinforced Concrete (RC) and steel structures. In addition, the keynote lecture highlights the performance of FRPs, including carbon, glass and basalt fibers and their hybrid combinations, as well as their epoxy as bonding agents all under normal and harsh environment such as elevated temperature and humid-saline environment. Furthermore, it provides a collective perspective on a number of limitations, challenges and research needs associated with sustainable and durable implementation of FRPs as successful externally-bonded strengthening and retrofitting materials.

EXPERIMENTAL AND FINITE ELEMENT (FE) STUDIES ON SHEAR BEHAVIORS OF REINFORCED CONCRETE (RC) BEAMS WITH CIRCULAR WEB OPENINGS

2021-08-26T08:49:48+00:00

The introduction of openings into reinforced concrete (RC) elements leads to reductions in the element’s overall
structural capacity and stiffness. These reductions attributed to stresses concentrations and local cracking at the
openings region. This paper presents a study aimed at investigating the influence of web openings at shear span of RC
beam on its shear behavior. A total of three beams with circular openings and one beam without opening were fabricated
and tested. The opening location and size, and shear span-to-depth ratios, were considered as the main parameters. The
FE model using ANSYS14.5 software was calibrated with the experimental results to ensure that the simulation process
is correct. Furthermore, the specimens were analyzed using ANSYS14.5 with considering the above mentioned
parameters. The results showed that the early collapse of the beam occurred when the openings located in a high shear
region. Furthermore, by comparing the non-linear FE analysis results with those from experimental tests, results were
showed good agreement

EFFECT OF ATMOSPHERIC STEAM CURING PARAMETERS ON CONCRETE STRENGTH AND DURABILITY

2021-08-26T08:41:06+00:00

Concrete steam curing under atmospheric pressure provides moisture and increases the temperature up to 100oC for
accelerating the curing process. This research identifies and optimizes steam curing parameters for producing precast
electrical poles in a Sudanese industrial entity. These parameters include a delay period after casting (DT) of 0, 2, 3, 4
& 6 hours, a maximum curing temperatures (T) of 50, 60 &70oC maintained for a specific curing period (CT) of 2, 3,
4 and 5 hrs. To attain this aim, several laboratory experiments have been carried out to measure compressive strengths
after 7 days of the above curing regimes that are compared to values of specimens subjected to conventional water
curing method. Then Taguchi methodology has been utilized to identify DT=3hrs, CT= 4hrs and T= 70oC as the
optimum curing regime and DT as the most effective parameter. Furthermore, specimens cured under this optimum
cycle have further tested for flexural strength and durability performance (sulphate and chloride ingress for periods up
to 12 months) and compared with water-cured ones. The results show that the steam-curing provides better performance
at 3 days for flexural strength and similar or superior long-term durability of concrete compared for water-curing

CO-ROTATIONAL FORMULATION AND IMPLEMENTATION OF AN INVARIANT-BASED MODEL FOR GEOMETRICALLY NONLINEAR ANALYSES OF COMPOSITES

2021-08-26T08:30:37+00:00

A co-rotational formulation and implementation of an invariant-based anisotropic plasticity model is presented for
geometrically nonlinear analyses of Fiber Reinforced Polymer (FRP) composites. The anisotropic constitutive
equations are formulated in the format of isotropic tensors functions. The model assumes an anisotropic pressure
dependent yield function, and in addition to this, a non-associated plastic potential in order to model more realistic
plastic deformations in FRP. The formulation is then cast in the co-rotational framework and implemented in the
commercial finite element software Abaqus/Standard via the means of the user-defined capability UMAT. The finite
deformation kinematics within the co-rotational frame are described and the important aspects regarding the numerical
treatment and implementation are discussed. The performance of the model is assessed via a set of numerical
simulations, which demonstrate its applicability and robustness.

CIVIL ENGINEERING AND THE SDGs

2021-08-26T08:24:31+00:00

Civil Engineering is a professional engineering discipline that deals with the planning, design, construction, and maintenance of the physical and naturally built environment, including works such as roads, bridges, canals, dams, airports, sewerage systems, pipelines and railways. On the other hand, the sustainable development goads (SDGs) are a collection of 17 global goals and some 169 targets set by the United Nations General Assembly in 2015, as the World transforming sustainable Agenda for 2030. In this presentation the author made an effort to define targets of the 17 goals that directly or indirectly link to civil engineering in the hope that the civil engineering community of the Sudan could organize themselves with the related communities to achieve these targets within the deadline of 2030

CHARACTERIZATION OF JEBAL MEIDOUB VOLCANIC ASH AND PUMICE AS CEMENT REPLACING MATERIALS FOR USE IN BLENDED CEMENTS

2021-08-26T08:16:23+00:00

The aim of this paper to evaluate the pozzolanic characteristics of the volcanic ash and pumice obtained from Jebal Meidoub (Meidoub Mountains) in western Sudan (Darfur) as potential Supplementary Cementitious Materials for use in blended cement and concrete. To achieve desired fineness, two types of local mills have been developed with high efficiency, one is a ball mill for laboratory purposes and another is a grinding mill for commercial production. Three natural Pozzolanic samples have been obtained, one is volcanic ash powder (MVA), another is pumice (MP), and the third contains a mixture of volcanic ash and pumice as found in the nature (MVP). This study has investigated the chemical and physical characteristics of the samples and their pozzolanic activities with Ordinary Portland cement (OPC) at different replacement levels of cement by weight, namely 10, 20, 30, 40, and 50%. The results of the chemical analysis have shown that all samples could be classified as Class N of the ASTM C618. The strength activity indices of the three samples at 20% level were found to be 81, 90, and 90% respectively. These results indicate that the Jebal Meidoub Pozzolans are potential supplementary cementitious materials for use in blended cement.

CHALLENGES CONFRONTING THE PROFESSIONAL PERSONALITY OF THE CIVIL ENGINEER IN SUDAN

2021-08-26T08:01:34+00:00

The construction industry is considered as one of the important industries regarding their outputs and products. The civil engineer in this industry plays key roles as a team leader. In order to achieve his/her duties the civil engineer should have some professional skills & characteristics to enable doing his/her jobs. This paper addressed the challenges confronting the professional personality of the civil engineer in Sudan regarding the observations about shortcomings in performance. A theoretical frame was established in the mentioned topic and data was compiled using a formal questionnaire. The paper proved that the professional personality of the civil engineer in Sudan suffers lack in skills and knowledge where some recommendations were issued regarding educational syllabus, training and professional degrees in order to mitigate the impact of such shortcomings.

BUILDING INFORMATION MODELLING FOR CONSTRUCTABILITY ASSESSMENT OF BUILDINGS DESIGN

2021-08-25T12:27:21+00:00

Implementation of constructability principles in the AEC industry offers improved construction performance with smooth project delivery and savings in time and money. Previous studies suggest that appraising design constructability at the concept design phases provides great benefits to clients, contractors and designers. Considering the complexity of current practice in buildings design, there is a need to provide a decision support tool that assists the design team to assess their design constructability, utilizing embedded information in the design model. Such targeted tool is most valuable at the early stage of buildings design that constructability is considered in the design solution starting from its inception. Therefore, this research investigates how contemporary process- and object-oriented models can be employed assesse the design constructability, informing decision making at an early stage that supports design optimization.

AXIAL CAPACITY OF LIGHTWEIGHT AGGREGATE CONCRETE FILLED CIRCULAR STEEL TUBES COLUMNS SUBJECTED TO ECCENTRIC LOADING

2021-08-25T12:12:43+00:00

This paper presents an experimental study on the behavior of lightweight aggregate concrete-filled steel tubes (LACFT) under eccentric loading. 54 circular specimens with different load eccentricity distances (10, 20 and 35mm); thickness to width ratio (t/D=11.4 and 13.5); and length to width ratio (L/D = 3, 7, and 14) tested to examine the bearing capacity. Significant parameters influencing LACFT column's bearing capacity, failure mechanism and failure mode all studied and analyzed. Comparison between the predicted results by AISC-LRFD and CHN DBJ 13-51-2003 codes showed lower and applicable bearing capacities with slightly overestimated values for L/D≥14 than that measured during the experiments respectively, while the results gained by CHN CECS 28:90 showed a good agreement with the experimental results and slightly overestimated the values for L/D≥ 14 too. This study shows that bearing capacity of LACFT steel columns subjected to eccentric loading is conservative.

APPLYING LEAN CONSTRUCTION CONCEPTS TO CONSTRUCTION INDUSTRY IN SUDAN

2021-08-25T11:55:56+00:00

This paper deals with the yield line analysis of orthotropic reinforced concrete two-way slab under the effect of uniformly distributed pressure load. The analysis was based on the method developed by Johansson, in which a general formula was derived to calculate the ultimate positive bending moment for the long span. The general formula depends mainly on the geometric dimensions resulting from the yield lines pattern as well as the moment's coefficients that have been used to relate the calculated moments with other moments. The moment's coefficients have been derived numerically using STAAD-Pro Software by adopting nine cases of boundary conditions with using different spans ratios range from 1.0 to 2.0. For the nine cases and with using different spans ratios, the ultimate bending moments have been calculated using yield line method. The results obtained were compared to that extracted from the BS8110 Code as well as those obtained using STAAD-Pro Software

ANALYSIS OF TWO-WAY SLAB USING YIELD LINE METHOD

2021-08-25T11:50:00+00:00

AN INTEGRATED APPROACH TOWARDS IMPLEMENTING WATER RESOURCES MANAGEMENT IN NORTH AFRICA

2021-08-25T11:16:27+00:00

Northern Africa is the driest region of the continent and is characterized by its limited water resources associated with a higher vulnerability to the risks from climate. Today, the available conventional renewable water resources from surface and groundwater are already not enough to sustain the water demand. Besides existing challenges to water management under scarcity and rapidly growing population and urbanization, climate change will impact on the availability and demand for water resources and water services. This calls for better characterization and analysis of water resources availability and demand, especially in such highly vulnerable regions like the Northern Africa region. This paper provides a clear picture of the status of water resources and an evaluation of the progress made so far by the Northern African countries to address the challenges related to sustainable water resources. It treats principal aspects of water resources while providing (i) an assessment of water resources development (ii) an evaluation of water resources utilization - supply and demand - by main sectors (domestic, agriculture, and industries), emphasizing the usage in urban and rural areas. Particular attention has been given by the region governments to improve access to water by focusing on water governance, institutional, technical and economic solutions. In the last decade, all the sub region countries have taken the challenge to improve water resources management by adopting water policies through a master plan for sustainable water resource management. These policies are different across the various countries, and its effective implementation requires a significant commitment among all the partners of the water sector The paper concludes with selected policy and technical recommendations pertaining to water resources development and management and to the increase effectiveness of water use and demand in the Northern Africa region. Some recommendations have been formulated into four key areas: adaptive actions and resource governance, raising awareness and capacity building, research and assessment; and cross-sector collaboration and cooperation. On all levels we as, scientists’ academicians, have to work together with various leaders from state and local levels and both public and private sectors to form various networks and shape research and politics priorities and craft new tools to sustain our precious water resources.