Abstract: In this paper, the torsion capacity of ultimate point on rectangular beams with spiral reinforcements in the torsion direction and its anti-direction are investigated. Therefore, models of above-mentioned beams have been numerically analyzed under various loads using ANSYS software. It was observed that, spirallyreinforced prismatic beam and beam with spiral links, show lower torsion capacity than beam with normal links also in anti-direction. The result is that the concrete regulations are violated in this case.
Abstract: The intelligent fuzzy input estimator is used to estimate
the input force of the rigid bar structural system in this study. The
fuzzy Kalman filter without the input term and the fuzzy weighting
recursive least square estimator are two main portions of this method.
The practicability and accuracy of the proposed method were verified
with numerical simulations from which the input forces of a rigid bar
structural system were estimated from the output responses. In order to
examine the accuracy of the proposed method, a rigid bar structural
system is subjected to periodic sinusoidal dynamic loading. The
excellent performance of this estimator is demonstrated by comparing
it with the use of difference weighting function and improper the
initial process noise covariance. The estimated results have a good
agreement with the true values in all cases tested.
Abstract: Without uncertainty by applying external loads on
beams, bending is created. The created bending in I-beams, puts one
of the flanges in tension and the other one in compression. With increasing of bending, compression flange buckled and beam in out
of its plane direction twisted, this twisting well-known as Lateral Torsional Buckling. Providing bending moment varieties along the
beam, the critical moment is greater than the case its under pure bending. In other words, the value of bending gradient coefficient is
always greater than unite. In this article by the use of " ANSYS 10.0" software near 80 3-D finite element models developed for the
propose of analyzing beams` lateral torsional buckling and surveying influence of slenderness on beams' bending gradient coefficient.
Results show that, presented Cb coefficient via AISC is not correct for some of beams and value of this coefficient is smaller than what proposed by AISC. Therefore instead of using a constant Cb for each
case of loading , a function with two criterion for calculation of Cb coefficient for some cases is proposed.
Abstract: In the modern construction practices, industrial wastes
or by-products are largely used as raw materials in cement and
concrete. These impart many benefits to the environment and bringabout
an economic impact because the cost of waste disposal is
constantly increasing due to strict environmental regulations. It was
reported in literature that the leakage of oil onto concrete element in
older cement grinding unit resulted in concrete with greater resistance
to freezing and thawing. This effect was thought to be similar to
adding an air-entraining chemical admixture to concrete. This paper
presents an investigation on the load deflection behaviour and crack
patterns of reinforced concrete (RC) beams subjected to four point
loading. Ten 120x260x1900 mm beams were cast with 100%
ordinary Portland cement (OPC) concrete, 20% fly ash (FA) and 20%
rice husk ash (RHA) blended cement concrete. 0.15% dosage of
admixtures (used engine oil, new engine oil, and superplasticizer)
was used throughout the experiment. Results show that OPC and
OPC/RHA RC beams containing used engine oil and superplasticizer
exhibit higher capacity, 18-26% than their corresponding control
mix.
Abstract: The large and small-scale shaking table tests, which
was conducted for investigating damage evolution of piles inside
liquefied soil, are numerically simulated and experimental verified by the3D nonlinear finite element analysis. Damage evolution of
elasto-plastic circular steel piles and reinforced concrete (RC) one with cracking and yield of reinforcement are focused on, and the failure patterns and residual damages are captured by the proposed constitutive models. The superstructure excitation behind quay wall is
reproduced as well.
Abstract: Shear walls are used in most of the tall buildings for
carrying the lateral load. When openings for doors or windows are
necessary to be existed in the shear walls, a special type of the shear
walls is used called "coupled shear walls" which in some cases is
stiffened by specific beams and so, called "stiffened coupled shear
walls".
In this paper, a mathematical method for geometrically nonlinear
analysis of the stiffened coupled shear walls has been presented.
Then, a suitable formulation for determining the critical load of the
stiffened coupled shear walls under gravity force has been proposed.
The governing differential equations for equilibrium and deformation
of the stiffened coupled shear walls have been obtained by setting up
the equilibrium equations and the moment-curvature relationships for
each wall. Because of the complexity of the differential equation, the
energy method has been adopted for approximate solution of the
equations.
Abstract: In this paper is reported an analysis about the outdoor air pollution of the urban centre of the city of Messina. The variations of the most critical pollutants concentrations (PM10, O3, CO, C6H6) and their trends respect of climatic parameters and vehicular traffic have been studied. Linear regressions have been effectuated for representing the relations among the pollutants; the differences between pollutants concentrations on weekend/weekday were also analyzed. In order to evaluate air pollution and its effects on human health, a method for calculating a pollution index was implemented and applied in the urban centre of the city. This index is based on the weighted mean of the most detrimental air pollutants concentrations respect of their limit values for protection of human health. The analyzed data of the polluting substances were collected by the Assessorship of the Environment of the Regional Province of Messina in the year 2004. A statistical analysis of the air quality index trends is also reported.
Abstract: The cable tower of Liede Bridge is a double-column curved-lever arched-beam portal framed structure. Being novel and unique in structure, its cable tower differs in complexity from traditional ones. This paper analyzes the ultimate load capacity of cable tower by adopting the finite element calculations and model tests which indicate that constitutive relations applied here give a better simulation of actual failure process of prestressed reinforced concrete. In vertical load, horizontal load and overloading tests, the stepped loading of the tower model is of linear relationship, and the test data has good repeatability. All suggests that the cable tower has good bearing capacity, rational design and high emergency capacity.
Abstract: In this paper, the optimum weight and cost of a laminated composite plate is seeked, while it undergoes the heaviest load prior to a complete failure. Various failure criteria are defined for such structures in the literature. In this work, the Tsai-Hill theory is used as the failure criterion. The theory of analysis was based on the Classical Lamination Theory (CLT). A newly type of Genetic Algorithm (GA) as an optimization technique with a direct use of real variables was employed. Yet, since the optimization via GAs is a long process, and the major time is consumed through the analysis, Radial Basis Function Neural Networks (RBFNN) was employed in predicting the output from the analysis. Thus, the process of optimization will be carried out through a hybrid neuro-GA environment, and the procedure will be carried out until a predicted optimum solution is achieved.
Abstract: Optimization of rational geometrical and mechanical
parameters of panel with curved plywood ribs is considered in this
paper. The panel consists of cylindrical plywood ribs manufactured
from Finish plywood, upper and bottom plywood flange, stiffness
diaphragms. Panel is filled with foam. Minimal ratio of structure self
weight and load that could be applied to structure is considered as
rationality criteria. Optimization is done, by using classical beam
theory without nonlinearities. Optimization of discreet design
variables is done by Genetic algorithm.
Abstract: Ten simply supported grossly underreinforced
tapered concrete beams of full size were tested upto complete
collapse under flexural effect .Out of 10 beams, 5 beams were
nonfibrous and the remaining beams contained fibres. The beams
had a variation in the tapered angle as 2°, 4°, 6°, 8° and 10°. The
concrete mix, conventional steel and the type of fibre used were
held constant. Flat corrugated steel fibres were utilized as
secondary reinforcement. The strength and stability parameters
were measured. It is established that the fibrous tapered beams can
be used economically in earthquake prone areas.
Abstract: Understanding how airborne pathogens are
transported through hospital wards is essential for determining the
infection risk to patients and healthcare workers. This study utilizes
Computational Fluid Dynamics (CFD) simulations to explore
possible pathogen transport within a six-bed partitioned Nightingalestyle
hospital ward.
Grid independence of a ward model was addressed using the Grid
Convergence Index (GCI) from solutions obtained using three fullystructured
grids. Pathogens were simulated using source terms in
conjunction with a scalar transport equation and a RANS turbulence
model. Errors were found to be less than 4% in the calculation of air
velocities but an average of 13% was seen in the scalar field.
A parametric study of variations in the pathogen release point
illustrated that its distribution is strongly influenced by the local
velocity field and the degree of air mixing present.
Abstract: Binder drainage test is widely used to set an upper
limit to the design binder content of porous asphalt. However, the
presence of high amount of fine particles in the drained binder may
affect the accuracy of the test result. This paper presents a study to
characterize the composition and particle size distribution of fine
particles accumulated in the drained binder. Fine aggregates and filler
in the drained binder were extracted using a suitable solvent. Then,
wet and dry sieve analysis was carried out to identify the actual
composition of the extracted fine aggregates and filler. From the
results, almost half of the drained binder consisted of fine aggregates
and this significantly affects the accuracy of the design binder content
of porous asphalt mix. This simple finding highlights the importance
of taking into account the presence of fine aggregates in the
calculation of drained binder.
Abstract: In this study rack systems that are structural storage
units of warehouses have been analyzed as structural with Finite
Element Method (FEA). Each cell of discussed rack system storages
pallets which have from 800 kg to 1000 kg weights and
0.80x1.15x1.50 m dimensions. Under this load, total deformations
and equivalent stresses of structural elements and principal stresses,
tensile stresses and shear stresses of connection elements have been
analyzed. The results of analyses have been evaluated according to
resistance limits of structural and connection elements. Obtained
results have been presented as visual and magnitude.
Abstract: Stage bus operated in the mixed traffic might always meet many problems about low quality and reliability of services. The low quality and reliability of bus service can make the system not attractive and directly reduce the interest of using bus service. This paper presents the result of field investigation and analysis of on-time performance and service regularity of stage bus in mixed traffic. Data for analysis was collected from the field by on-board observation along the Ipoh-Lumut corridor in Perak, Malaysia. From analysis and discussion, it can be concluded that on-time performance and service regularity varies depend on station, typical day, time period, operation characteristics of bus and characteristics of traffic. The on-time performance and service regularity of stage bus in mixed traffic can be derived by using data collected by onboard survey. It is clear that on-time performance and service regularity of the existing stage bus system was low.
Abstract: Energy consumption is a very important topic these
days especially regarding air conditioning in residential buildings,
since this takes the biggest amount of energy in buildings total
consumption, residential buildings constitute the biggest percentage
of energy consumption in Bahrain.
This research reflects on the effects of shading percentage in
different solar orientations on the energy consumption inside
residential buildings (domestic dwellings).
The research as found that, there are different effects of shading in
changing building orientation:
• 0.69% for the shading percentage 25% when the building is
oriented to the north (0º);
• 18.59% for 75% of shading in north-west orientation
(325º);
• The best effect for shading is in north-west orientation
(315º);
• The less effect for shading was in case of the building
orientation is the north (0º).
Abstract: Among many different methods that are used for
optimizing different engineering problems mathematical (numerical)
optimization techniques are very important because they can easily
be used and are consistent with most of engineering problems. Many
studies and researches are done on stability analysis of three
dimensional (3D) slopes and the relating probable slip surfaces and
determination of factors of safety, but in most of them force
equilibrium equations, as in simplified 2D methods, are considered
only in two directions. In other words for decreasing mathematical
calculations and also for simplifying purposes the force equilibrium
equation in 3rd direction is omitted. This point is considered in just a
few numbers of previous studies and most of them have only given a
factor of safety and they haven-t made enough effort to find the most
probable slip surface. In this study shapes of the slip surfaces are
modeled, and safety factors are calculated considering the force
equilibrium equations in all three directions, and also the moment
equilibrium equation is satisfied in the slip direction, and using
nonlinear programming techniques the shape of the most probable
slip surface is determined. The model which is used in this study is a
3D model that is composed of three upper surfaces which can cover
all defined and probable slip surfaces. In this research the meshing
process is done in a way that all elements are prismatic with
quadrilateral cross sections, and the safety factor is defined on this
quadrilateral surface in the base of the element which is a part of the
whole slip surface. The method that is used in this study to find the
most probable slip surface is the non-linear programming method in
which the objective function that must get optimized is the factor of
safety that is a function of the soil properties and the coordinates of
the nodes on the probable slip surface. The main reason for using
non-linear programming method in this research is its quick
convergence to the desired responses. The final results show a good
compatibility with the previously used classical and 2D methods and
also show a reasonable convergence speed.
Abstract: The predictability of masonry arch bridges and their
behaviour is widely considered doubtful due to the lack of knowledge
about the conditions of a given masonry arch bridge. The assessment
methods for masonry arch bridges are MEXE, ARCHIE, RING and
Frame Analysis Method. The material properties of the masonry and
fill material are extremely difficult to determine accurately.
Consequently, it is necessary to examine the effect of load dispersal
angle through the fill material, the effect of variations in the stiffness
of the masonry, the tensile strength of the masonry mortar continuum
and the compressive strength of the masonry mortar continuum. It is
also important to understand the effect of fill material on load
dispersal angle to determine their influence on ratings. In this paper a
series of parametric studies, to examine the sensitivity of assessment
ratings to the various sets of input data required by the frame analysis
method, are carried out.
Abstract: This study investigated the effect of cross sectional
geometry on sediment transport rate. The processes of sediment
transport are generally associated to environmental management,
such as pollution caused by the forming of suspended sediment in the
channel network of a watershed and preserving physical habitats and
native vegetations, and engineering applications, such as the
influence of sediment transport on hydraulic structures and flood
control design. Many equations have been proposed for computing
the sediment transport, the influence of many variables on sediment
transport has been understood; however, the effect of other variables
still requires further research. For open channel flow, sediment
transport capacity is recognized to be a function of friction slope,
flow velocity, grain size, grain roughness and form roughness, the
hydraulic radius of the bed section and the type and quantity of
vegetation cover. The effect of cross sectional geometry of the
channel on sediment transport is one of the variables that need
additional investigation. The width-depth ratio (W/d) is a
comparative indicator of the channel shape. The width is the total
distance across the channel and the depth is the mean depth of the
channel. The mean depth is best calculated as total cross-sectional
area divided by the top width. Channels with high W/d ratios tend to
be shallow and wide, while channels with low (W/d) ratios tend to be
narrow and deep. In this study, the effects of the width-depth ratio on
sediment transport was demonstrated theoretically by inserting the
shape factor in sediment continuity equation and analytically by
utilizing the field data sets for Yalobusha River. It was found by
utilizing the two approaches as a width-depth ratio increases the
sediment transport decreases.
Abstract: Road authorities have confronted problems to
maintaining the serviceability of road infrastructure systems by using
various traditional methods of contracting. As a solution to these
problems, many road authorities have started contracting out road
maintenance works to the private sector based on performance
measures. This contracting method is named Performance-Based
Maintenance Contracting (PBMC). It is considered more costeffective
than other traditional methods of contracting. It has a
substantial success records in many developed and developing
countries over the last two decades. This paper discusses and
analyses the potential issues to be considered before the introduction
of PBMC in a country.