Tạp chí KHCN Xây dựng số 2/2009
Ngày tạo : 15/07/2015
Tạp chí KHCN Xây dựng số 2/2009
ThS. Vũ Thành Trung, GS. Yukio Tamura, PGS. Shuyang Cao,
PGS. Yong Quan
So sánh các hệ số
áp lực trên nhà thấp tầng mái bằng bằng cách sử dụng mô phỏng LES (Large Eddy
Simulation)
KS. Nguyễn Thanh Hưng
Ứng dụng lý thuyết độ tin cậy vào việc khảo sát và đánh giá độ tin cậy của
sàn phằng bê tông ứng lực trước
ThS. Nguyễn Quang Phú, GS. Jiang Linhua, GS. Liu Jiaping
Dự đoán môdun đàn
hồi của bê tông tính năng cao có chứa phụ gia giảm co ngót
ThS. Lê Trung Phong, PGS.TS. Nguyễn Lê Ninh
Về bản chất của hệ số ứng xử trong tiêu chuẩn thiết kế các công trình chịu động
đất TCXDVN 375:2006
ThS. Vũ Hoàng Hưng, TS. Nguyễn Quang Hùng, GS. Li Tongchun
Vài vấn đề cần quan
tâm khi thiết kế đập vòm cao
ThS. Nguyễn Duy Hiếu, TS. Trần Bá Việt
Ảnh hưởng của việc dưỡng hộ bên trong đến tính chất cơ lý của bê tông cốt
liệu rỗng chịu lực có độ chảy cao
ThS. Vũ Quốc Vương, GS. TS. Jiang Linhua, GS. Miao Changwen, ThS. Trịnh Quốc
Công, ThS. Vũ Hoàng Hưng
Xác định áp lực lên ván khuôn của bê tông tự đầm dùng cát nhân tạo
TS. Trịnh Việt Cường, TS. Bùi Đức Hải, TS. Trần Huy Tấn
Quan trắc phân phối tải trọng lên cọc và đất nền dưới móng một công trình có
tầng ngầm
KS. Nguyễn Mạnh Hà, KS. Diêm
Công Trang
Khảo sát một số
phương pháp xác định số cải chính toạ độ cho kết quả định vị tuyệt đối của máy
GPS cầm tay
ABSTRACTS
Comparison of pressure
coefficients on a flat-roofed low-rise building by using LES (Large Eddy
Simulation) (pp.3-5)
MEng. Vu Thanh Trung, Prof. Yukio Tamura,
A/Prof. Shuyang Cao, A/Prof. Yong Quan
The paper presents
simulation of Large Eddy Simulation (LES) of flow around a flat-roofed low-rise
building in a turbulent boundary layer. We simulate both the approaching
turbulent boundary layer and the flow around a model, and compare the numerical
simulations against experimental results of mean pressure and fluctuating
pressure coefficients.
Application of
reliability theory to the investigation and assessment of the reliability of
prestressed concrete flat slabs (pp. 6-11)
Eng. nguyen thanh Hung
In structural analysis, safety factors on loads, materials and working
conditions are mentioned in design standards in order to account for the
influence of relevant parameters on the bearing capacity of a structure that
have not been foreseen by the designer.
In order to assess the influence level of these parameters, we need to
calculate, investigate and assess the reliability of the structure according to
the stages: design, construction, manufacture and operation,..
In this paper, the author presents the calculation, investigation and
assessment of the reliability of prestressed concrete flat slabs at the time of
releasing hydraulic jacks and at the stage of being operated, using the
investigation data obtained from a designed and constructed structure,
according to ACI 318-1999.
Prediction of the elastic
modulus of high-performance concrete containing shrinkage reducing admixture
(pp.12-16)
MEng. Nguyen Quang Phu, Prof.
Jiang Linhua, Prof. Liu Jiaping
In the current study, every effort has been made to some experimental
models to predict the elastic modulus of high-performance concrete (HPC) based
on some known characteristics of the concrete mix (the percentage of mineral
admixtures, aggregate, and water to cementitious materials ratios, etc). In
this study, to predict the elastic modulus of HPC containing shrinkage reducing
admixture based on the compressive strength, two kinds of water and
cementitious materials ratio (W/CM = 0.22 and 0.40) and four percentages of
shrinkage reducing admixture (0%, 1%, 2% and 4%) respectively for each W/CM
were selected for experiments. The concrete specimens were cast, cured and
tested after 7 and 28 days of age to determine the elastic modulus and
compressive strength. The reliability of the model was verified with some
independent experimental data and comparison with some experimental models from
the literature.
On the essence of the resistant factor in the design
standard of structures for earthquake resistance TCXDVN 375:2006 (pp.17-20)
MEng. LE
Trung Phong, A/Prof. Dr. Nguyen Le Ninh
Resistant factor (structural factor) used in structural design is a new concept
for engineers nowadays. Before the issuance of the TCXDVN 375:2006[1],
engineers had to use some foreign standards or other reference materials to
apply the seismic load on structures if required. The TCXDVN 375:2006[1]
mentioned about the resistant factor (structural factor) and it is the skeleton
factor of this standard. The essence of the resistant factor is the load
reduction factor, it considers the inelastic stage of the material without
nonlinear analysis for the structure. To take this advantage, the structure has
to contain a minimum requirement of ductility.
Some problems that need to be considered in
design of high-arch dam (pp.21-28)
MEng. VU HoAng HUng, Dr. NguyEn Quang HUng, Prof.
Li Tongchun
Arch dam is usually the best choice in construction of high retaining dam
because of its characteristics in safety and economic. The recently trend of
arch dam construction is how to build the dam not only higher, thinner and more
aesthetic but also get the highest safety. In arch dam design, it is necessary
to consider some issues such as: the optimization of configuration, the methods
to analyze stress, stress-control criteria, type and mechanism of fracture, the
assessment of degree of safety, the capacity in seismic resistance of arch dam.
The paper briefly introduces the achievements and research direction of the
above problems in design and construction of arch dam in the world, especially
in China
which is a nation with more experiences in design and application of high-arch
dams.
Determining
the formwork pressure of self-compacting concrete using artificial sand
(pp.29-33)
MEng. Vu Quoc Vuong,
Prof. Dr. Jiang LinHua, Prof. Miao ChangWen, MEng. Trinh Quoc Cong, MEng. Vu
Hoang Hung
Self-compacting
concrete (SCC) has been widely using recently. Because of special properties of
Self compacting concrete, the mechanical behavior of this fresh concrete is
much different compared to normal vibrated concrete. Generally, the lack of
vibration reduces the pressure, but on the other hand the changed consistency
of SCC increases the load. In this study, authors developed mathematical model
based on the equilibrium condition within the casting shell element to
determine the formwork pressure of SCC using artificial sand.
The influence of internal water curing on
physical-mechanical properties of structural porous aggregates concrete with
high flowability (pp.34-38)
MEng. Nguyen
Duy Hieu, Dr. Tran Ba Viet
From the past to
this time, concrete has been externally cured from its surfaces. This method
seems to be helpful for ordinary concrete. However, for high-strength concrete
in general and self-leveling structural porous aggregate concretes in
particular, the effectiveness of external water curing is very low due to the
limitation of water movement from the inside to the outside and vice versa.
In this paper, the authors present an experimental study in order to determine
the influence of internal water curing on physical-mechanical properties of
structural porous aggregates concrete with high flowability.
Monitoring the
distribution of structural load on piles and raft under a building with
basements (pp.39-45)
Dr. Trinh Viet Cuong, Dr.
Bui Duc Hai, Dr. Tran Huy Tan
Normally, the piled foundations of buildings with basements are designed
with the assuming that the whole structural load is transferred to piles.
However, theorical and experimental studies have showed that the load are
always shared between the piles and the soil under the basement raft. Analysis
methods that account for the interaction between piles and raft have been
applied in the design of many high rise buildings abroad. This report presents
the results from monitoring the distribution of structural load on piles and
raft under a building in Hanoi.
Experimental results show that the raft takes over 20% of the total load
although the building is constructed in an area of unfavourable soil condition.
Investigation of some calculation methods of coordinate correction
numbers for the absolute positioning results by portable GPS devices (pp.46-52)
Eng. Nguyen Manh Ha,
Eng. Diem Cong Trang
In this paper, the authors recommend and investigate some calculation
methods of coordinate correction numbers in order to improve the accuracy of
absolute positioning results by portable GPS devices and to form the basis for
further study to expand the device’s scope of application in topographical
surveying and military activities.
