Abstract: The evaluation of energy release rate and centre Crack
Opening Displacement (COD) for circumferential Through-Wall
Cracked (TWC) pipes is an important issue in the assessment of
critical crack length for unstable fracture. The ability to predict crack
growth continues to be an important component of research for
several structural materials. Crack growth predictions can aid the
understanding of the useful life of a structural component and the
determination of inspection intervals and criteria. In this context,
studies were carried out at CSIR-SERC on Nuclear Power Plant
(NPP) piping components subjected to monotonic as well as cyclic
loading to assess the damage for crack growth due to low-cycle
fatigue in circumferentially TWC pipes.
Abstract: Safety, river environment, and sediment utilization are the elements of the target of sediment management. As a change in an element by sediment management, may affect the other two elements, and the priority among three elements depends on stakeholders. It is necessary to develop a method to evaluate the effect of sediment management on each element and an integrated evaluation method for socio-economic effect. In this study, taking Mount Merapi basin as an investigation field, the method for an active volcanic basin was developed. An integrated evaluation method for sediment management was discussed from a socio-economic point on safety, environment, and sediment utilization and a case study of sediment management was evaluated by means of this method. To evaluate the effect of sediment management, some parameters on safety, utilization, and environment have been introduced. From a utilization point of view, job opportunity, additional income of local people, and tax income to local government were used to evaluate the effectiveness of sediment management. The risk degree of river infrastructure was used to describe the effect of sediment management on a safety aspect. To evaluate the effects of sediment management on environment, the mean diameter of grain size distribution of riverbed surface was used. On the coordinate system designating these elements, the direction of change in basin condition by sediment management can be predicted, so that the most preferable sediment management can be decided. The results indicate that the cases of sediment management tend to give the negative impacts on sediment utilization. However, these sediment managements will give positive impacts on safety and environment condition. Evaluation result from a social-economic point of view shows that the case study of sediment management reduces job opportunity and additional income for inhabitants as well as tax income for government. Therefore, it is necessary to make another policy for creating job opportunity for inhabitants to support these sediment managements.
Abstract: A submerged horizontal plate type breakwater is
pointed out as an efficient wave protection device for cage culture in
marine fishery. In order to reveal the wave elimination principle of this
type breakwater, boundary element method is utilized to investigate
this problem. The flow field and the trajectory of water particles are
studied carefully. The flow field analysis shows that: the interaction of
incident wave and adverse current above the plate disturbs the water
domain drastically. This can slow down the horizontal velocity and
vertical velocity of the water particles.
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: The aim of this paper is the analysis and preservation of lime kilns, focusing on the structure, construction, and functionality of vertical shaft lime kilns of the Cap Corse in Corsica. Plans and sections of two lime kilns are presented in detail, providing an overall picture of this specific industrial heritage. The potential damage areas are identified performing structural analysis of a lime kiln using the finite element method. A restoration and strengthening technique that satisfies the directions of the Charter of Venice is presented using post-tensioning tendons. Recommendations are given to preserve and promote these important historical structures integrating them into the custom footpath.
Abstract: Asphalt surfaces are exposed to various weather
conditions and dynamic loading caused by passing trucks and
vehicles. In such situations, asphalt cement shows so different
rheological-mechanical behavior. If asphalt cement isn-t compatible
enough, asphalt layer will be damaged immediately and expensive
repairing procedures should be performed then. To overcome this
problem, researchers study on mechanical improved asphalt cement.
In this study, bentonite was used in order to modify bitumen
characteristics and the modified bitumen's characteristics were
investigated by asphalt cement tests. Then, the optimal bitumen
content in various compounds was determined and asphalt samples
with different contents of additives were prepared and tested. Results
show using this kind of additive not only has caused improvement in
bitumen mechanical properties, but also improvement in Marshall
Parameters was achieved.
Abstract: Cement, the most widely used construction material
is very brittle and characterized by low tensile strength and strain
capacity. Macro to nano fibers are added to cement to provide
tensile strength and ductility to it. Carbon Nanotube (CNT), one of
the nanofibers, has proven to be a promising reinforcing material in
the cement composites because of its outstanding mechanical
properties and its ability to close cracks at the nano level. The
experimental investigations for CNT reinforced cement is costly,
time consuming and involves huge number of trials. Mathematical
modeling of CNT reinforced cement can be done effectively and
efficiently to arrive at the mechanical properties and to reduce the
number of trials in the experiments. Hence, an attempt is made to
numerically study the effective mechanical properties of CNT
reinforced cement numerically using Representative Volume
Element (RVE) method. The enhancement in its mechanical
properties for different percentage of CNTs is studied in detail.
Abstract: This paper investigated the impact of ceiling height and window head heights variation on daylighting inside architectural teaching studio with a full width window. In architectural education, using the studio is more than normal classroom in most credit hours. Therefore, window position, size and dimension of studio have direct influence on level of daylighting. Daylighting design is a critical factor that improves student learning, concentration and behavior, in addition to these, it also reduces energy consumption. The methodology of analysis involves using Radiance in IES software under overcast and cloudy sky in Malaysia. It has been established that presentation of daylighting of architecture studio can be enhanced by changing the ceiling heights and window level, because, different ceiling heights and window head heights can contribute to different range of daylight levels.
Abstract: Land surface temperature (LST) is an important
parameter to study in urban climate. The understanding of the
influence of biophysical factors could improve the establishment of
modeling urban thermal landscape. It is well established that climate
hold a great influence on the urban landscape. However, it has been
recognize that climate has a low priority in urban planning process,
due to the complex nature of its influence. This study will focus on
the relatively cloud free Landsat Thematic Mapper image of the study
area, acquired on the 2nd March 2006. Correlation analyses were
conducted to identify the relationship of LST to the biophysical
factors; vegetation indices, impervious surface, and albedo to
investigate the variation of LST. We suggest that the results can be
considered by the stackholders during decision-making process to
create a cooler and comfortable environment in the urban landscape
for city dwellers.
Abstract: A method to predict the column size for displacement based design of reinforced concrete frame buildings with higher target inter storey drift is reported here. The column depth derived from empirical relation as a function of given beam section, target inter-story drift, building plan features and common displacement based design parameters is used. Regarding the high drift requirement, a minimum column-beam moment capacity ratio is maintained during capacity design. The method is used in designing four, eight and twelve story frame buildings with displacement based design for three percent target inter storey drift. Non linear time history analysis of the designed buildings are performed under five artificial ground motions to show that the columns are found elastic enough to avoid column sway mechanism assuring that for the design the column size can be used with or without minor changes.
Abstract: In built-up structures, one of the effective ways of
dissipating unwanted vibration is to exploit the occurrence of slip at
the interfaces of structural laminates. The present work focuses on
the dynamic analysis of welded structures. A mathematical
formulation has been developed for the mechanism of slip damping
in layered and welded mild steel beams with unequal thickness
subjected to both periodic and non-periodic forces. It is observed that
a number of vital parameters such as; thickness ratio, pressure
distribution characteristics, relative slip and kinematic co-efficient of
friction at the interfaces, nature of exciting forces, length and
thickness of the beam specimen govern the damping characteristics of
these structures. Experimental verification has been carried out to
validate the analysis and study the effect of these parameters. The
developed damping model for the structure is found to be in fairly
good agreement with the measured data. Finally, the results of the
analysis are discussed and rationalized.
Abstract: Eight steel reinforced concrete beams (SRC), were
fabricated and tested under earthquake type cyclic loading. The
effectiveness of intermediate stiffeners, such as mid-span stiffener and
plastic hinge zone stiffeners, in enhancing composite action and
ductility of SRC beams was investigated. The effectiveness of
strengthened beam-to-column (SBC) and weakened beam-to-column
(WBC) connections in enhancing beam ductility was also studied. It
was found that: (1) All the specimens possessed fairly high flexural
ductility and were found adequate for structures in high seismic zones.
(2) WBC connections induced stress concentration which caused extra
damage to concrete near the flange tapering zone. This extra damage
inhibited the flexural strength development and the ductility of the
specimens with WBC connections to some extent. (3) Specimens with
SBC connections demonstrated higher flexural strength and ductility
compared to specimens with WBC connections. (4) The intermediate
stiffeners, especially combination of plastic hinge zone stiffener and
mid span stiffeners, have an obvious effect in enhancing the ductility
of the beams with SBC connection.
Abstract: The objective of this study is to evaluate the threshold
stress of the clay with sand subgrade soil. Threshold stress can be
defined as the stress level above which cyclic loading leads to
excessive deformation and eventual failure. The thickness
determination of highways formations using the threshold stress
approach is a more realistic assessment of the soil behaviour because
it is subjected to repeated loadings from moving vehicles. Threshold
stress can be evaluated by plastic strain criterion, which is based on
the accumulated plastic strain behaviour during cyclic loadings [1].
Several conditions of the all-round pressure the subgrade soil namely,
zero confinement, low all-round pressure and high all-round pressure
are investigated. The threshold stresses of various soil conditions are
determined. Threshold stress of the soil are 60%, 31% and 38.6% for
unconfined partially saturated sample, low effective stress saturated
sample, high effective stress saturated sample respectively.
Abstract: Roundabout work on the principle of circulation and
entry flows, where the maximum entry flow rates depend largely on
circulating flow bearing in mind that entry flows must give away to
circulating flows. Where an existing roundabout has a road hump
installed at the entry arm, it can be hypothesized that the kinematics
of vehicles may prevent the entry arm from achieving optimum
performance. Road humps are traffic calming devices placed across
road width solely as speed reduction mechanism. They are the
preferred traffic calming option in Malaysia and often used on single
and dual carriageway local routes. The speed limit on local routes is
30mph (50 km/hr). Road humps in their various forms achieved the
biggest mean speed reduction (based on a mean speed before traffic
calming of 30mph) of up to 10mph or 16 km/hr according to the UK
Department of Transport. The underlying aim of reduced speed
should be to achieve a 'safe' distribution of speeds which reflects the
function of the road and the impacts on the local community.
Constraining safe distribution of speeds may lead to poor drivers
timing and delayed reflex reaction that can probably cause accident.
Previous studies on road hump impact have focused mainly on speed
reduction, traffic volume, noise and vibrations, discomfort and delay
from the use of road humps. The paper is aimed at optimal entry and
circulating flow induced by road humps. Results show that
roundabout entry and circulating flow perform better in
circumstances where there is no road hump at entrance.
Abstract: The correct design of the regulators structure requires complete prediction of the ultimate dimensions of the scour hole profile formed downstream the solid apron. The study of scour downstream regulator is studied either on solid aprons by means of velocity distribution or on movable bed by studying the topography of the scour hole formed in the downstream. In this paper, a new technique was developed to study the scour hole downstream regulators on movable beds. The study was divided into two categories; the first is to find out the sum of the lengths of rigid apron behind the gates in addition to the length of scour hole formed downstream, while the second is to find the minimum length of rigid apron behind the gates to prevent erosion downstream it. The study covers free and submerged hydraulic jump conditions in both symmetrical and asymmetrical under-gated regulations. From the comparison between the studied categories, we found that the minimum length of rigid apron to prevent scour (Ls) is greater than the sum of the lengths of rigid apron and that of scour hole formed behind it (L+Xs). On the other hand, the scour hole dimensions in case of submerged hydraulic jump is always greater than free one, also the scour hole dimensions in asymmetrical operation is greater than symmetrical one.
Abstract: Analytical procedure was carried out in this paper to
calculate the ultimate load capacity of reinforced concrete corbels
strengthened or repaired externally with CFRP sheets. Strut and tie
method and shear friction method proposed earlier for analyzing
reinforced concrete corbels were modified to incorporate the effect of
external CFRP sheets bonded to the corbel. The points of weakness
of any method that lead to an inaccuracy, especially when
overestimating test results were checked and discussed. Comparison
of prediction with the test data indicates that the ratio of test /
calculated ultimate load is 0.82 and 1.17 using strut and tie method
and shear friction method, respectively. If the limits of maximum
shear stress is followed, the calculated ultimate load capacity using
shear friction method was found to underestimates test data
considerably.
Abstract: Considering the merits and limitations of energy dissipation system, seismic isolation system and suspension system, a new earthquake resistant system is proposed and is demonstrated numerically through a frame-core structure. Base isolators and story isolators are installed in the proposed system. The former “isolates" the frame from the foundation and the latter “separates" the frame from the center core. Equations of motion are formulated to study the response of the proposed structural system to strong earthquake motion. As compared with the fixed-base building system, the proposed structural system shows substantial reduction on structural response.
Abstract: The world-s largest Pre-stressed Concrete Cylinder
Pipe (PCCP) water supply project had a series of pipe failures which
occurred between 1999 and 2001. This has led the Man-Made River
Authority (MMRA), the authority in charge of the implementation
and operation of the project, to setup a rehabilitation plan for the
conveyance system while maintaining the uninterrupted flow of
water to consumers. At the same time, MMRA recognized the need
for a long term management tool that would facilitate repair and
maintenance decisions and enable taking the appropriate preventive
measures through continuous monitoring and estimation of the
remaining life of each pipe. This management tool is known as the
Pipe Risk Management System (PRMS) and now in operation at
MMRA. Both the rehabilitation plan and the PRMS require the
availability of complete and accurate pipe construction and
manufacturing data
This paper describes a systematic approach of data collection,
analysis, evaluation and correction for the construction and
manufacturing data files of phase I pipes which are the platform for
the PRMS database and any other related decision support system.
Abstract: Demolitions of buildings have created a lot of waste
and one of it is clay bricks. The waste clay bricks were ground to
roughly cement fineness and used to partially replaced cement at
10%, 20% and 30% with w/b ratio of 0.6 and tested at 7, 28, 60, 90
and 120 days. The result shows that the compressive strength of GCB
concrete increases over age however, decreases as the level of
replacements increases. It was also found that 10% replacement of
GCB gave the highest compressive strength, however for optimum
replacement, 30% was chosen as it still attained strength of grade 30
concrete. In terms of durability performances, results show that GCB
replacement up to 30% was found to be efficient in reducing water
absorption as well as water permeability. These studies show that
GCB has the potential to be used as partial cement replacement in
making concrete.
Abstract: The Eulerian numerical method is proposed to analyze
the explosion in tunnel. Based on this method, an original software
M-MMIC2D is developed by Cµ program language. With this
software, the explosion problem in the tunnel with three
expansion-chambers is numerically simulated, and the results are
found to be in full agreement with the observed experimental data.