Tạp chí KHCNXD

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.

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