According
to the actual measurement data, probability models of horizontal wind load were
obtained based on wind velocity statistic and power spectral density function
of fluctuating wind velocity through stochastic sampling and using spectrum
analysis method. Through the comparison of two models, probability models of
horizontal wind load based on probability models of fluctuating wind velocity
were obtained by revising the mean and variance of fluctuating wind velocity.
Results show that the variance takes lower value when the power spectral
density function of fluctuating wind velocity is used to obtain the probability
model of horizontal wind load. The quadratic term of fluctuating wind velocity
takes a small contribution value in total wind load with almost no contribution
to the model of horizontal wind load. It is convenient for practical
engineering to obtain the models of horizontal wind load by using probability
models of fluctuating wind velocity.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
This
work studies the influence of mechanical and geometrical characteristics of the
concrete and the soil on the stresses in a mat foundation. In this study, the
soil-structure interaction is modeled by two parameters, the modulus of
subgrade vertical reaction (k) and the modulus of subgrade horizontal reaction
(2T). These two parameters are dependent on the geometrical and mechanical
characteristics of the system. Results of this study show a sensitivity of
solicitations to variations of geometrical and mechanical characteristics of
the model. Although solicitations in the plate are sensitive to mechanical
properties of concrete, these solicitations are strongly influenced by the
mechanical and geometrical characteristics of the soil mass. However, it should
be noted that the influence of Eb is denoted in the center of the plate whereas
the Es feels almost in the same manner over the entire extent of the plate.
This study also shows that for the same load cases, the values of the torsion
moment and shear stress are not significant those of bending moments and normal
stresses, respectively.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Concrete
research is gradually shifting from the conventional strength-based approach to
durability-centred in the past decade. Durability is the measure of the
robustness of constructed facilities against deterioration tendencies. The rate
of deterioration is affected by the loading condition, and more importantly the
physical and chemical nature of the host environments. This paper reports the
experimental investigation of unstressed concrete substructure in the natural
(uncontaminated) and cassava’s hydrocyanide effluent-polluted soils on the
compressive and flexural strengths of buried concrete specimens for a maximum
of 84 days. The compressive strengths of the cubes were tested every 7 days
until the 84th day, while the beams were only subjected to third-point loading
flexural tests at age 84 days. The compressive strength of concrete specimens
in the two soil environments increased, though the trend was lower in the
polluted soil. The strength reduced by 2.50% to 9.47% between the 7th and 28th
days, but steadily between the 28th and 84th days with strength loss of 9.95%
(COV = 2.64%). The load-deflection curves were quadratic for the beams in the
two geo-environments. The beams in cyanide-polluted soil lost 34.5% of its
flexural stiffness, while its loss of load-carrying capacities at the first
crack and ultimate failure was 15.8% and 20% respectively. Higher degree of
deterioration is certain for loaded concrete substructures in similar
conditions. Hence, prior knowledge of soil chemistry is crucial to determining
suitable concrete grade and nominal cover for durable substructural elements.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Three
beams of concrete strength 20 N/mm2 at age 28 days were separately reinforced
with bamboo, rattan and steel bars of same percentage, while the stirrups were
essentially mild steel bars. The beams were subjected to centre-point flexural
loading according to BS 1881 to evaluate the flexural behaviour. The YS of
bamboo and rattan bars were 13% and 45% of that of steel respectively, while
their UTS were 16% and 62% of that of steel in the same order. The elongation
of bamboo, rattan and steel were 7.42%, 10% and 14.7% respectively. The natural
rebars were less than the 12% minimum requirement of BS 4449. The
load-deflection plots of bamboo and steel RC beams were quadratic, while rattan
RC beams had curvilinear trend. The stiffness of bamboo RC beams (BB) and
rattan RC beams (RB) were 32% and 13.5% of the stiffness of steel RC beams
(SB). The post-first crack residual flexural strength was 41% for BB and SB,
while RB was 25%. Moreover, the moment capacities of BB and RB corresponded to
51% and 21% respectively of the capacity of steel RC beams. The remarkable gap
between the flexural capacities of the natural rebars and that of steel can be
traced not only to the tensile strength but also the weak bonding at the
bar-concrete interface. It can be concluded that the bamboo bars are suitable
rebars for non-load bearing and lightweight RC flexural structures, while more
pre-strengthening treatment is required more importantly for rattan for
improved interfacial bonding and load-carrying capacity.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
The
structural behaviour of Precast Lightweight Foamed Concrete Panel (PLFP) under
flexural load is investigated by using ABAQUS 6.13. The PLFP is made up of two
Whyte’s with a polystyrene insulator placed in between them using a double
shear truss connector of diameter 6mm placed at an angle 45°. The panel is
reinforced with both vertical and horizontal steel reinforcement of 9 mm
diameter. Four panels with varying dimensions are simulated to investigate
their Ultimate Strength and Load-deflection profile. The results show that the
length to thickness ratio of the panel is the major contributing factor to the
ultimate strength of the PLFP. From the load deflection curve, the panel with
the least deflection has the highest thickness which also results in a high
ultimate strength recorded at 34.43 KN.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
This
water carries large amounts of stone powder, which leads to complex nature of
environmental problem so these waste material needs to be utilized meaningfully
in economic way. The degree of compaction of a soil is measured in terms of its
dry unit weight Al-Khamkha mixed with Jerash cohesive soil at different amount
ranges from 0%, 5%, 10%, 15%, up to 50% and compaction characteristics of
Jerash cohesive soil without and with different amount of Al-Khamkha was
studied. This investigation show that as the amount of Al-Khamkha increase from
0% to 15%, the dry unit weight of Jerash cohesive soil increase from 14.4 KN/m3
at 0% of Al-Khamkha to 16.5 KN/m3 at 15% and after that .any increase of
Al-Khamkha decrease the dry unit weight. On the other hand, the optimum water
content of the Jerash cohesive soil was increases with increasing the percentage
of Al-Khamkha on the cohesive soil.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
These
existing reinforced concrete buildings need to be evaluated to determine the
capacity to resist seismic loads. The behavior of a building during earthquakes
depends critically on its overall shape, size and geometry. Conventional
approach to earthquake resistant design of buildings depends upon providing the
building with strength, stiffness and inelastic deformation capacity which are
great enough to withstand a given level of earthquake-generated force. This is
generally accomplished through the selection of an appropriate building
configuration and the careful detailing of structural members. In this
research, nonlinear pushover analysis has been used to evaluate the seismic
performance of three buildings with three different plans having same area and
height. This method determines the base shear capacity of the building and
performance level of each part of building under varying intensity of seismic
force. The results of effects of different plan on seismic response of
buildings have been presented in terms of displacement, base shear and plastic
hinge pattern.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
a
new method is proposed to evaluate the seismic behavior of buried jointed water
pipeline networks subjected to wave propagation. First, using finite element
method and solid elements, different kinds of currently used connections in the
network are modeled, and their nonlinear behavior in all directions is
obtained. Second, a 950-meter long network consisting of ductile iron pipes
segments of 6-meter length and springs characterizing the connections, are
modeled using beam elements. Three-component displacement record of the Tabas
earthquake is applied to the network considering the time lag between support
inputs, and the nonlinear soil-pipe interaction. The record is applied once in
North-South direction and once in East-West direction with different wave
propagation velocities. Results of interest such as stress values and rotations
at various points of the network are then obtained, and critical points are
introduced in each direction. Results show that the points other than the
critical ones at the network intersections remain elastic.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
Flooring
costs may reach 20% of single-story building construction expenditure, and the
consumption of concrete for floors may come to 40% - 50% of the total size of
concrete. Thereby, the efficient design of floor will reduce materials
consumption and labor, and will increase the endurance of the floor. Fiber
reinforcement reduces the thickness of the subfloor about 20% - 30%, hence
enabling to reduce the consumption of cement and fillers. The use of fiber
meshes will enable to save 30% - 40% of steel. Despite the flexible use of
fiber in concrete reinforcement saves effort and money, still fiber reinforced
concrete is lacking additional regulations in Jordan.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
The
evaluation of seismic performance of existing buildings has received a great
attention. Current research works and observations indicate that The Sudan have
low-to-moderate seismic regions. Most of existing buildings are designed only
for gravity load. The objective of this paper is to assess the seismic
performance of existing RC buildings in The Sudan. Four typical buildings were
investigated using pushover analysis according to ATC-40. They were designed
according to the Regulations for earthquake-resistant design of buildings in
Egypt (ESEE) and International Building Code (IBC2012). Results showed that the
buildings designed considering by ESEE and IBC2012 loads were found adequate
and satisfied the Immediate Occupancy (IO) acceptance criteria according to
ATC-40. The comparison of the pushover curve shows that the stiffness of frames
is larger when using ESEE Regulations compared to the IBC2012 design. This
means that ESEE design procedure provides a greater capability to resist
seismic load than the IBC2012 design.
Website: http://www.arjonline.org/engineering/american-research-journal-of-civil-and-structural-engineering/
