Abstract: The seismic feedback experiences in Algeria have
shown higher percentage of damages for non-code conforming
reinforced concrete (RC) buildings. Furthermore, the vulnerability of
these buildings was further aggravated due to presence of many
factors (e.g. weak the seismic capacity of these buildings, shorts
columns, Pounding effect, etc.).
Consequently Seismic risk assessments were carried out on
populations of buildings to identify the buildings most likely to
undergo losses during an earthquake. The results of such studies are
important in the mitigation of losses under future seismic events as
they allow strengthening intervention and disaster management plans
to be drawn up.
Within this paper, the state of the existing structures is assessed using
"the vulnerability index" method. This method allows the
classification of RC constructions taking into account both, structural
and non structural parameters, considered to be ones of the main
parameters governing the vulnerability of the structure. Based on
seismic feedback from past earthquakes DPM (damage probability
matrices) were developed too.
Abstract: A reliable estimate of the average bond stress within
the anchorage of steel reinforcing bars in tension is critically
important for the design of reinforced concrete member. This paper
describes part of a recently completed experimental research program
in the Centre for Infrastructure Engineering and Safety (CIES) at the
University of New South Wales, Sydney, Australia aimed at
assessing the effects of different factors on the anchorage
requirements of modern high strength steel reinforcing bars. The
study found that an increase in the anchorage length and bar diameter
generally leads to a reduction of the average ultimate bond stress. By
the extension of a well established analytical model of bond and
anchorage, it is shown here that the differences in the average
ultimate bond stress for different anchorage lengths is associated with
the variable degree of plastic deformation in the tensile zone of the
concrete surrounding the bar.
Abstract: Regarding previous research studies it was concluded
that thin-walled fiber-cement composites are able to conduct electric
current under specific conditions. This property is ensured by using
of various kinds of carbon materials. Though carbon fibers are less
conductive than metal fibers, composites with carbon fibers were
evaluated as better current conductors than the composites with metal
fibers. The level of electric conductivity is monitored by the means of
impedance measurement of designed samples. These composites
could be used for a range of applications such as heating of
trafficable surfaces or shielding of electro-magnetic fields.
The aim of the present research was to design an element with the
ability to monitor internal processes in building structures and
prevent them from collapsing. As a typical element for laboratory
testing there was chosen a concrete column, which was repeatedly
subjected to load by simple pressure with continual monitoring of
changes in electrical properties.
Abstract: This study aims to identify processes, current
situations, and issues of recycling systems for four home appliances,
namely, air conditioners, television receivers, refrigerators, and
washing machines, among e-wastes in China and Japan for
understanding and comparison of their characteristics. In accordance
with results of a literature search, review of information disclosed
online, and questionnaire survey conducted, conclusions of the study
boil down to:
(1)The results show that in Japan most of the home appliances
mentioned above have been collected through home appliance
recycling tickets, resulting in an issue of “requiring some effort" in
treatment and recycling stages, and most plants have contracted out
their e-waste recycling.
(2)It is found out that advantages of the recycling system in Japan
include easiness to monitor concrete data and thorough
environmental friendliness ensured while its disadvantages include
illegal dumping and export. It becomes apparent that advantages of
the recycling system in China include a high reuse rate, low
treatment cost, and fewer illegal dumping while its disadvantages
include less safe reused products, environmental pollution caused by
e-waste treatment, illegal import, and difficulty in obtaining data.
Abstract: The first and basic cause of the failure of concrete is repeated freezing (thawing) of moisture contained in the pores, microcracks, and cavities of the concrete. On transition to ice, water existing in the free state in cracks increases in volume, expanding the recess in which freezing occurs. A reduction in strength below the initial value is to be expected and further cycle of freezing and thawing have a further marked effect. By using some experimental parameters like nuclear magnetic resonance variation (NMR), enthalpy-temperature (or heat capacity) variation, we can resolve between the various water states and their effect on concrete properties during cooling through the freezing transition temperature range. The main objective of this paper is to describe the principal type of water responsible for the reduction in strength and structural damage (frost damage) of concrete following repeated freeze –thaw cycles. Some experimental work was carried out at the institute of cryogenics to determine what happens to water in concrete during the freezing transition.
Abstract: In the paper the results of calculations of the dynamic
response of a multi-storey reinforced concrete building to a strong
mining shock originated from the main region of mining activity in
Poland (i.e. the Legnica-Glogow Copper District) are presented. The
representative time histories of accelerations registered in three
directions were used as ground motion data in calculations of the
dynamic response of the structure. Two variants of a numerical model
were applied: the model including only structural elements of the
building and the model including both structural and non-structural
elements (i.e. partition walls and ventilation ducts made of brick). It
turned out that non-structural elements of multi-storey RC buildings
have a small impact of about 10 % on natural frequencies of these
structures. It was also proved that the dynamic response of building
to mining shock obtained in case of inclusion of all non-structural
elements in the numerical model is about 20 % smaller than in case
of consideration of structural elements only. The principal stresses
obtained in calculations of dynamic response of multi-storey building
to strong mining shock are situated on the level of about 30% of
values obtained from static analysis (dead load).
Abstract: Reinforced Concrete (RC) structures strengthened
with fiber reinforced polymer (FRP) lack in thermal resistance under
elevated temperatures in the event of fire. This phenomenon led to
the lining of strengthened concrete with thin high performance
cementitious composites (THPCC) to protect the substrate against
elevated temperature. Elevated temperature effects on THPCC, based
on different cementitious materials have been studied in the past but
high-alumina cement (HAC)-based THPCC have not been well
characterized. This research study will focus on the THPCC based on
HAC replaced by 60%, 70%, 80% and 85% of ground granulated
blast furnace slag (GGBS). Samples were evaluated by the
measurement of their mechanical strength (28 & 56 days of curing)
after exposed to 400°C, 600°C and 28°C of room temperature for
comparison and corroborated by their microstructure study. Results
showed that among all mixtures, the mix containing only HAC
showed the highest compressive strength after exposed to 600°C as
compared to other mixtures. However, the tensile strength of THPCC
made of HAC and 60% GGBS content was comparable to the
THPCC with HAC only after exposed to 600°C. Field emission
scanning electron microscopy (FESEM) images of THPCC
accompanying Energy Dispersive X-ray (EDX) microanalysis
revealed that the microstructure deteriorated considerably after
exposure to elevated temperatures which led to the decrease in
mechanical strength.
Abstract: Concrete pavement has superior durability and longer
structural life than asphalt pavement. Concrete pavement requires
less maintenance compared to asphalt pavement which requires maintenance and major rehabilitation. Use of the concrete pavement
has been grown over the past decade in developing countries. Fibre reinforced concrete (FRC) has been successfully used in design of concrete pavement in past decade. In this research, the effect of fibre
volume fraction in modulus of rupture, load-deflection, equivalent flexural strength (fe,3) and the equivalent flexural strength ratio (Re,3)
has been used in different fibre volume fraction. Crimped-type flat
steel fibre of size 50 x 2.0 x 0.6 mm was used with 1.0%, 1.5% and 2.0% volume fraction. Beam specimens of size 500 x 100 x 100 mm were used for flexural as well as with JCI method for analysis flexural toughness, equivalent flexural strength. It was obtained as the 2% fibre volume fractions; reduce 45% of the concrete pavement
thickness.
Abstract: These Nowadays the explosion of bombs or explosive
materials such as gas and oil near or inside the buildings cause some
losses in installations and building components. This has made the
engineers to make the buildings and their components resistance
against the effects of explosion. These activities lead to provide
regulations and different methods. The above regulations are mostly
focused on the explosion effects resulting from the vehicles around
the buildings. Therefore, the explosion resulting from the vehicles
outside the buildings will be studied in this research.
In the present study, the main goals are to investigate the
explosion load effects on the structures located on the piles with the
specific quantity of plasticity and observing the permissible response
of these structures. The concentrated mass system and the spring with
two degree of freedom will be used to study the structural system.
Abstract: Human activities are increasingly based on the use of remote resources and services, and on the interaction between
remotely located parties that may know little about each other. Mobile agents must be prepared to execute on different hosts with
various environmental security conditions. The aim of this paper is to
propose a trust based mechanism to improve the security of mobile
agents and allow their execution in various environments. Thus, an
adaptive trust mechanism is proposed. It is based on the dynamic interaction between the agent and the environment. Information
collected during the interaction enables generation of an environment
key. This key informs on the host-s trust degree and permits the mobile agent to adapt its execution. Trust estimation is based on
concrete parameters values. Thus, in case of distrust, the source of problem can be located and a mobile agent appropriate behavior can
be selected.
Abstract: Basic ingredients of concrete are cement, fine aggregate, coarse aggregate and water. To produce a concrete of certain specific properties, optimum proportion of these ingredients are mixed. The important factors which govern the mix design are grade of concrete, type of cement and size, shape and grading of aggregates. Concrete mix design method is based on experimentally evolved empirical relationship between the factors in the choice of mix design. Basic draw backs of this method are that it does not produce desired strength, calculations are cumbersome and a number of tables are to be referred for arriving at trial mix proportion moreover, the variation in attainment of desired strength is uncertain below the target strength and may even fail. To solve this problem, a lot of cubes of standard grades were prepared and attained 28 days strength determined for different combination of cement, fine aggregate, coarse aggregate and water. An artificial neural network (ANN) was prepared using these data. The input of ANN were grade of concrete, type of cement, size, shape and grading of aggregates and output were proportions of various ingredients. With the help of these inputs and outputs, ANN was trained using feed forward back proportion model. Finally trained ANN was validated, it was seen that it gave the result with/ error of maximum 4 to 5%. Hence, specific type of concrete can be prepared from given material properties and proportions of these materials can be quickly evaluated using the proposed ANN.
Abstract: Reinforced concrete has good durability and excellent structural performance. But there are cases of early deterioration due to a number of factors, one prominent factor being corrosion of steel reinforcement. The process of corrosion sets in due to ingress of moisture, oxygen and other ingredients into the body of concrete, which is unsound, permeable and absorbent. Cracks due to structural and other causes such as creep, shrinkage, etc also allow ingress of moisture and other harmful ingredients and thus accelerate the rate of corrosion. There are several interactive factors both external and internal, which lead to corrosion of reinforcement and ultimately failure of structures. Suitable addition of mineral admixture like silica fume (SF) in concrete improves the strength and durability of concrete due to considerable improvement in the microstructure of concrete composites, especially at the transition zone. Secondary reinforcement in the form of fibre is added to concrete, which provides three dimensional random reinforcement in the entire mass of concrete. Reinforced concrete beams of size 0.1 m X 0.15 m and length 1m have been cast using M 35 grade of concrete. The beams after curing process were subjected to corrosion process by impressing an external Direct Current (Galvanostatic Method) for a period of 15 days under stressed and unstressed conditions. The corroded beams were tested by applying two point loads to determine the ultimate load carrying capacity and cracking pattern and the results of specimens were compared with that of the companion specimens. Gravimetric method is used to quantify corrosion that has occurred.
Abstract: Reactive powder concretes (RPC) are characterized by
particle diameter not exceeding 600 μm and having very high
compressive and tensile strengths. This paper describes a new
generation of micro concrete, which has an initial, as well as a final,
high physicomechanical performance. To achieve this, we replaced
the Portland cement (15% by weight) by materials rich in Silica (Slag
and Dune Sand).
The results obtained from tests carried out on RPC show that
compressive and tensile strengths increase when adding the additions,
thus improving the compactness of mixtures via filler and pozzolanic
effect.
With a reduction of the aggregate phase in the RPC and the
abundance of dune sand (south Algeria) and slag (industrial byproduct
of blast furnace), the use of the RPC will allow Algeria to
fulfil economical as well as ecological requirements.
Abstract: The seismic rehabilitation designs of two reinforced
concrete school buildings, representative of a wide stock of similar
edifices designed under earlier editions of the Italian Technical
Standards, are presented in this paper. The mutual retrofit solution
elaborated for the two buildings consists in the incorporation of a
dissipative bracing system including pressurized fluid viscous springdampers
as passive protective devices. The mechanical parameters,
layouts and locations selected for the constituting elements of the
system; the architectural renovation projects developed to properly
incorporate the structural interventions and improve the appearance
of the buildings; highlights of the installation works already
completed in one of the two structures; and a synthesis of the
performance assessment analyses carried out in original and
rehabilitated conditions, are illustrated. The results of the analyses
show a remarkable enhancement of the seismic response capacities of
both structures. This allows reaching the high performance objectives
postulated in the retrofit designs with much lower costs and
architectural intrusion as compared to traditional rehabilitation
interventions designed for the same objectives.
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: A new analytical method to predict the torsional
capacity and behavior of R.C multi-cell box girders strengthened with
carbon fiber reinforced polymer (CFRP) sheets is presented.
Modification was done on the Softened Truss Model (STM) in the
proposed method; the concrete torsional problem is solved by
combining the equilibrium conditions, compatibility conditions and
constitutive laws of materials by taking into account the confinement
of concrete with CFRP sheets. A specific algorithm is developed to
predict the torsional behavior of reinforced concrete multi-cell box
girders with or without strengthening by CFRP sheets. Applications
of the developed method as an assessment tool to strengthened multicell
box girders with CFRP and first analytical example that
demonstrate the contribution of the CFRP materials on the torsional
response is also included.
Abstract: This paper presents the results of an experimental
investigation carried out to evaluate the shrinkage of High Strength
Concrete. High Strength Concrete is made by partially replacement of
cement by flyash and silica fume. The shrinkage of High Strength
Concrete has been studied using the different types of coarse and fine
aggregates i.e. Sandstone and Granite of 12.5 mm size and Yamuna
and Badarpur Sand. The Mix proportion of concrete is 1:0.8:2.2 with
water cement ratio as 0.30. Superplasticizer dose @ of 2% by weight
of cement is added to achieve the required degree of workability in
terms of compaction factor.
From the test results of the above investigation it can be concluded
that the shrinkage strain of High Strength Concrete increases with
age. The shrinkage strain of concrete with replacement of cement by
10% of Flyash and Silica fume respectively at various ages are more
(6 to 10%) than the shrinkage strain of concrete without Flyash and
Silica fume. The shrinkage strain of concrete with Badarpur sand as
Fine aggregate at 90 days is slightly less (10%) than that of concrete
with Yamuna Sand. Further, the shrinkage strain of concrete with
Granite as Coarse aggregate at 90 days is slightly less (6 to 7%) than
that of concrete with Sand stone as aggregate of same size. The
shrinkage strain of High Strength Concrete is also compared with that
of normal strength concrete. Test results show that the shrinkage
strain of high strength concrete is less than that of normal strength
concrete.
Abstract: Measurement and the following evaluation of
performance represent important part of management. The paper
focuses on indicators as the basic elements of performance
measurement system. It emphasizes a necessity of searching
requirements for quality indicators so that they can become part of
the useful system. It introduces standpoints for a systematic dividing
of indicators so that they have as high as possible informative value
of background sources for searching, analysis, designing and using of
indicators. It draws attention to requirements for indicators' quality
and at the same it deals with some dangers decreasing indicator's
informative value. It submits a draft of questions that should be
answered at the construction of indicator. It is obvious that particular
indicators need to be defined exactly to stimulate the desired
behavior in order to attain expected results. In the enclosure a
concrete example of the defined indicator in the concrete conditions
of a small firm is given. The authors of the paper pay attention to the
fact that a quality indicator makes it possible to get to the basic
causes of the problem and include the established facts into the
company information system. At the same time they emphasize that
developing of a quality indicator is a prerequisite for the utilization
of the system of measurement in management.
Abstract: This study examines the inelastic behavior of adjacent planar reinforced concrete (R.C.) frames subjected to strong ground motions. The investigation focuses on the effects of vertical ground motion on the seismic pounding. The examined structures are modeled and analyzed by RUAUMOKO dynamic nonlinear analysis program using reliable hysteretic models for both structural members and contact elements. It is found that the vertical ground motion mildly affects the seismic response of adjacent buildings subjected to structural pounding and, for this reason, it can be ignored from the displacement and interstorey drifts assessment. However, the structural damage is moderately affected by the vertical component of earthquakes.
Abstract: This paper presents a research conducted to investigate the effect of mixing process on polypropylene (PP) modified bitumen mixed with well graded aggregate to form modified bituminous concrete mix. Two mode of mixing, namely dry and wet with different concentration of polymer polypropylene was used with 80/100 pen bitumen, to evaluate the bituminous concrete mix properties. Three percentages of polymer varying from 1-3% by the weight of bitumen was used in this study. Three mixes namely control mix, wet mix and dry mix were prepared. Optimum binder content was calculated considering Marshall Stability, flow, air voids and Marshall Quotient at different bitumen content varying from 4% - 6.5% for control, dry and wet mix. Engineering properties thus obtained at the calculated optimum bitumen content revealed that wet mixing process is advantageous in comparison to dry mixing as it increases the stiffness of the mixture with the increase in polymer content in bitumen. Stiffness value for wet mix increases with the increase in polymer content which is beneficial in terms of rutting. 1% PP dry mix also shows enhanced stiffness, with the air void content limited to 4%.The flow behaviour of dry mix doesn't indicate any major difference with the increase in polymer content revealing that polymer acting as an aggregate only without affecting the viscosity of the binder in the mix. Polypropylene (PP) when interacted with 80 pen base bitumen enhances its performance characteristics which were brought about by altered rheological properties of the modified bitumen. The decrease in flow with the increase in binder content reflects the increase in viscosity of binder which induces the plastic flow in the mix. Workability index indicates that wet mix were easy to compact up to desired void ratio in comparison to dry mix samples.