Abstract: This paper presents the study of strengthening R/C
beams with large circular and square opening located at flexure zone
by Carbon Fiber Reinforced Polymer (CFRP) laminates. A total of
five beams were tested to failure under four point loading to
investigate the structural behavior including crack patterns, failure
mode, ultimate load and load deflection behaviour. Test results show
that large opening at flexure reduces the beam capacity and stiffness;
and increases cracking and deflection. A strengthening configuration
was designed for each un-strengthened beams based on their
respective crack patterns. CFRP laminates remarkably restore the
beam capacity of beam with large circular opening at flexure location
while 10% re-gain of beam capacity with square opening. The use of
CFRP laminates with the designed strengthening configuration could
significantly reduce excessive cracking and deflection and increase
the ultimate capacity and stiffness of beam.
Abstract: This paper presents results of an experimental study performed to investigate effect of incorporating silica fume on physico-mechanical properties and durability of resulting fly ash geopolymers. Geopolymer specimens were prepared by activating fly ash incorporated with additional silica fume in the range of 2.5% to 5%, with a mixture of sodium hydroxide and sodium silicate solution having Na2O content of 8%. For studying durability, 10% magnesium sulphate solution was used to immerse the specimens up to a period of 15 weeks during which visual observation, weight changes and strength changes were monitored regularly. Addition of silica fume lowers performance of geopolymer pastes. However, in mortars, addition of silica fume significantly enhanced physico-mechanical properties and durability.
Abstract: True stress-strain curve of railhead steel is required to
investigate the behaviour of railhead under wheel loading through elasto-plastic Finite Element (FE) analysis. To reduce the rate of wear, the railhead material is hardened through annealing and
quenching. The Australian standard rail sections are not fully hardened and hence suffer from non-uniform distribution of the
material property; usage of average properties in the FE modelling can potentially induce error in the predicted plastic strains. Coupons
obtained at varying depths of the railhead were, therefore, tested under axial tension and the strains were measured using strain gauges as well as an image analysis technique, known as the Particle Image Velocimetry (PIV). The head hardened steel exhibit existence of three distinct zones of yield strength; the yield strength as the ratio of the average yield strength provided in the standard (σyr=780MPa) and
the corresponding depth as the ratio of the head hardened zone along
the axis of symmetry are as follows: (1.17 σyr, 20%), (1.06 σyr, 20%-80%) and (0.71 σyr, > 80%). The stress-strain curves exhibit limited plastic zone with fracture occurring at strain less than 0.1.
Abstract: High level and high velocity flood flows are
potentially harmful to bridge piers as evidenced in many toppled
piers, and among them the single-column piers were considered as
the most vulnerable. The flood flow characteristic parameters
including drag coefficient, scouring and vortex shedding are built into
a pier-flood interaction model to investigate structural safety against
flood hazards considering the effects of local scouring, hydrodynamic
forces, and vortex induced resonance vibrations. By extracting the
pier-flood simulation results embedded in a neural networks code,
two cases of pier toppling occurred in typhoon days were reexamined:
(1) a bridge overcome by flash flood near a mountain side;
(2) a bridge washed off in flood across a wide channel near the
estuary. The modeling procedures and simulations are capable of
identifying the probable causes for the tumbled bridge piers during
heavy floods, which include the excessive pier bending moments and
resonance in structural vibrations.
Abstract: Chloride induced corrosion of steel reinforcement is
the main cause of deterioration of reinforced concrete marine
structures. This paper investigates the relative performance of
alternative repair options with respect to the deterioration of
reinforced concrete bridge elements in marine environments. Focus is
placed on the initiation phase of reinforcement corrosion. A
laboratory study is described which involved exposing concrete
samples to accelerated chloride-ion ingress. The study examined the
relative efficiencies of two repair methods, namely Ordinary Portland
Cement (OPC) concrete and a concrete which utilised Ground
Granulated Blastfurnace Cement (GGBS) as a partial cement
replacement. The mix designs and materials utilised were identical to
those implemented in the repair of a marine bridge on the South East
coast of Ireland in 2007. The results of this testing regime serve to
inform input variables employed in probabilistic modelling of
deterioration for subsequent reliability based analysis to compare the
relative performance of the studied repair options.
Abstract: In this study, we discussed the effects on the thermal
comfort of super high-rise residences that how effected by the high
thermal capacity structural components. We considered different
building orientations, structures, and insulation methods. We used the
dynamic simulation software THERB (simulation of the thermal
environment of residential buildings). It can estimate the temperature,
humidity, sensible temperature, and heating/cooling load for multiple
buildings. In the past studies, we examined the impact of
air-conditioning loads (hereinafter referred to as AC loads) on the
interior structural parts and the AC-usage patterns of super-high-rise
residences.
Super-high-rise residences have more structural components such
as pillars and beams than do ordinary apartment buildings. The
skeleton is generally made of concrete and steel, which have high
thermal-storage capacities. The thermal-storage capacity of
super-high-rise residences is considered to have a larger impact on the
AC load and thermal comfort than that of ordinary residences.
We show that the AC load of super-high-rise units would be
reduced by installing insulation on the surfaces of interior walls that
are not usually insulated in Japan.
Abstract: The aim of this study is to analyze influence of
differences of heat insulation methods on indoor thermal environment and comfort of apartment buildings.
This study analyzes indoor thermal environment and comfort on units of apartment buildings using calculation software "THERB" and
compares three different kinds of heat insulation methods. Those are
outside insulation on outside walls, inside insulation on outside walls and interior insulation. In terms of indoor thermal environment, outside insulation is the best to stabilize room temperature. In winter, room temperature on
outside insulation after heating is higher than other and it is kept 3-5 degrees higher through all night. But the surface temperature with
outside insulation did not dramatically increase when heating was used, which was 3 to 5oC lower than the temperature with other
insulation. The PMV of interior insulation fall nearly range of comfort when the heating and cooling was use.
Abstract: Both prognostic and diagnostic modes of a 3D baroclinic
model in hydrodynamic and sediment transport models of
the Princeton Ocean Model (POM) were conducted to separate
prognose and diagnose effects of different hydrodynamic factors on
transport of suspended sediment discharged from the rivers to the
Gulf of Thailand (GoT). Both transport modes of suspended sediment
distribution in the GoT were numerically simulated. It could be
concluded that the suspended sediment discharged from the rivers
around the GoT. Most of sediments in estuaries and coastal areas are
deposited outside the GoT under the condition of wind-driven current,
and very small amount of the sediments of them are transported
faraway. On the basis of wind forcing, sediments from the lower
GoT to the upper GoT are mainly transported south-northwestward
and also continuously moved north-southwestward. An obvious 3D
characteristic of suspended sediment transport is produced in the
wind-driven current residual circulation condition. In this study, the
transport patterns at the third layer are generally consistent with
the typhoon-induced strong currents in two case studies of Typhoon
Linda 1997. The case studies presented the prognostic and diagnostic
modes during 00UTC28OCT1997 to 12UTC06NOV1997 in a short
period with the current condition for pre-operation of the suspended
sediment transport model in estuaries and coastal areas.
Abstract: Water Sensitive Urban Design (WSUD) features are
increasingly used to treat and manage polluted stormwater runoff in urbanised areas. It is important to monitor and evaluate the effectiveness of the infrastructure in achieving their intended performance targets after constructing and operating these features
overtime. The paper presents the various methods of analysis used to
assess the effectiveness of the in-situ WSUD features, such as: onsite visual inspections during operational and non operational periods, maintenance audits and periodic water quality testing. The results will contribute to a better understanding of the operational and
maintenance needs of in-situ WSUD features and assist in providing recommendations to better manage life cycle performance.
Abstract: Public bus service plays a significant role in our
society as people movers and to facilitate travels within towns and districts. The quality of service of public bus is always being
regarded as poor, or rather, underestimated as second class means of transportation. Reliability of service, or the ability to deliver service as planned, is one key element in perceiving the quality of bus service and the punctuality index is one of the performance parameters in determining the service reliability. This study
concentrates on evaluating the reliability performance of bus operation using punctuality index assessment. A week data for each
of six city bus routes is recorded using the on-board methodology to calculate the punctuality index for city bus service in Kota Bharu. The results revealed that the punctuality index for the whole city bus network is 94.25% (LOS B).
Abstract: Auckland has a temperate climate with comfortable
warm, dry summers and mild, wet winters. An Auckland school
normally does not need air conditioning for cooling during the
summer and only need heating during the winter. The space hating
energy is the major portion of winter school energy consumption and
the winter energy consumption is major portion of annual school
energy consumption. School building thermal design should focus
on the winter thermal performance for reducing the space heating
energy. A number of Auckland schools- design data and energy
consumption data are used for this study. This pilot study
investigates the relationships between their energy consumption data
and school building design data to improve future school design for
energy efficiency.
Abstract: The demands of taller structures are becoming imperative almost everywhere in the world in addition to the challenges of material and labor cost, project time line etc. This paper conducted a study keeping in view the challenging nature of high-rise construction with no generic rules for deflection minimizations and frequency control. The effects of cyclonic wind and provision of outriggers on 28-storey, 42-storey and 57-storey are examined in this paper and certain conclusions are made which would pave way for researchers to conduct further study in this particular area of civil engineering. The results show that plan dimensions have vital impacts on structural heights. Increase of height while keeping the plan dimensions same, leads to the reduction in the lateral rigidity. To achieve required stiffness increase of bracings sizes as well as introduction of additional lateral resisting system such as belt truss and outriggers is required.
Abstract: Landfill gas, particularly methane is one of the
greenhouse gases which contributes to global warming. This paper presents the findings of a study on methane gas production from
simulated landfill reactor under saturated conditions. A reactor was constructed to represent a landfill cell of 2.5 m thickness on sandy
soil. The reactor was 0.2 m in diameter and 4 m in height. One meter of sand and pebble layer was packed at the bottom of the reactor
followed by 2.5 m of solid waste layer and 0.4 m of sand layer as the cover soil. Degradation of waste in the solid waste layer was at
acidification stage as indicated by the leachate quality with COD as
high as 55,511 mg/L and pH as low as 5.1. However, methanogenic
environment was established at the bottom sand layer after one year of operation indicated by pH of 7.2 and methane gas generation.
Leachate degradation took place as the leachate moved through the
sand layer at an infiltration of rate 0.7 cm/day. This resulted in landfill gas production of 77 mL/day/kg containing 55 to 65% methane. The application of sand layer contributed to the gas
production from landfill by an in-situ degradation of leachate in the
sand at the bottom of the landfill.
Abstract: This paper focuses on the Mega-Sub Controlled
Structure Systems (MSCSS) performances and characteristics
regarding the new control principle contained in MSCSS subjected to
strong earthquake excitations. The adopted control scheme consists of
modulated sub-structures where the control action is achieved by
viscous dampers and sub-structure own configuration. The
elastic-plastic time history analysis under severe earthquake excitation
is analyzed base on the Finite Element Analysis Method (FEAM), and
some comparison results are also given in this paper. The result shows
that the MSCSS systems can remarkably reduce vibrations effects
more than the mega-sub structure (MSS). The study illustrates that the
improved MSCSS presents good seismic resistance ability even at 1.2g
and can absorb seismic energy in the structure, thus imply that
structural members cross section can be reduce and achieve to good
economic characteristics. Furthermore, the elasto-plastic analysis
demonstrates that the MSCSS is accurate enough regarding
international building evaluation and design codes. This paper also
shows that the elasto-plastic dynamic analysis method is a reasonable
and reliable analysis method for structures subjected to strong
earthquake excitations and that the computed results are more precise.
Abstract: Sub-prime mortgage crisis which began in the US is
regarded as the most economic crisis since the Great Depression in the
early 20th century. Especially, hidden problems on efficient operation
of a business were disclosed at a time and many financial institutions
went bankrupt and filed for court receivership. The collapses of
physical market lead to bankruptcy of manufacturing and construction
businesses. This study is to analyze dynamic efficiency of construction
businesses during the five years at the turn of the global financial
crisis. By discovering the trend and stability of efficiency of a
construction business, this study-s objective is to improve
management efficiency of a construction business in the
ever-changing construction market. Variables were selected by
analyzing corporate information on top 20 construction businesses in
Korea and analyzed for static efficiency in 2008 and dynamic
efficiency between 2006 and 2010. Unlike other studies, this study
succeeded in deducing efficiency trend and stability of a construction
business for five years by using the DEA/Window model. Using the
analysis result, efficient and inefficient companies could be figured
out. In addition, relative efficiency among DMU was measured by
comparing the relationship between input and output variables of
construction businesses. This study can be used as a literature to
improve management efficiency for companies with low efficiency
based on efficiency analysis of construction businesses.
Abstract: The aim of the current study is to develop a numerical
tool that is capable of achieving an optimum shape and design of
hyperbolic cooling towers based on coupling a non-linear finite
element model developed in-house and a genetic algorithm
optimization technique. The objective function is set to be the
minimum weight of the tower. The geometric modeling of the tower
is represented by means of B-spline curves. The finite element
method is applied to model the elastic buckling behaviour of a tower
subjected to wind pressure and dead load. The study is divided into
two main parts. The first part investigates the optimum shape of the
tower corresponding to minimum weight assuming constant
thickness. The study is extended in the second part by introducing the
shell thickness as one of the design variables in order to achieve an
optimum shape and design. Design, functionality and practicality
constraints are applied.
Abstract: In the traditional architecture, buildings were designed
to achieve human comfort by using locally available building materials and construction technology which were more responsive to
their climatic and geographic condition. This paper will try to bring out the wisdom of the local masons and builders, often the inhabitants
themselves, about their way of living, and shaping their built environment, indoor and outdoor spaces, as a response to the local
climatic conditions, from the findings of a field
settlement.
Abstract: Researchers investigate arious strategies to develop composite beams and maximize the structural advantages. This study
attempted to conduct experiments and analysis of changes in the
neutral axis of positive moments of a Green Beam. Strain
compatibility analysis was used, and its efficiency was demonstrated
by comparing experimental and analytical values. In the comparison of
neutral axis, the difference between experimental and analytical values
was found to range from 8.8~26.2%. It was determined that strain
compatibility analysis can be useful for predicting the behaviors of
composite beams, with the ability to predict the behavior of not only
the elastic location of the composite member, but also of the plastic
location
Abstract: The article presents analysis results of maps of
expected subsidence in undermined areas for road repair
management. The analysis was done in the area of Karvina district in
the Czech Republic, including undermined areas with ongoing deep
mining activities or finished deep mining in years 2003 - 2009.
The article discusses the possibilities of local road maintenance
authorities to determine areas that will need most repairs in the future
with limited data available. Using the expected subsidence maps new
map of surface curvature was calculated. Combined with road maps
and historical data about repairs the result came for five main
categories of undermined areas, proving very simple tool for
management.
Abstract: Foundation of tower crane serves to ensure stability
against vertical and horizontal forces. If foundation stress is not
sufficient, tower crane may be subject to overturning, shearing or
foundation settlement. Therefore, engineering review of stable support
is a highly critical part of foundation design. However, there are not
many professionals who can conduct engineering review of tower
crane foundation and, if any, they have information only on a small
number of cranes in which they have hands-on experience. It is also
customary to rely on empirical knowledge and tower crane renter-s
recommendations rather than designing foundation on the basis of
engineering knowledge. Therefore, a foundation design automation
system considering not only lifting conditions but also overturning
risk, shearing and vertical force may facilitate production of foolproof
foundation design for experts and enable even non-experts to utilize
professional knowledge that only experts can access now. This study
proposes Automatic Design Algorithm for the Tower Crane
Foundations considering load and horizontal force.