Ngày tạo : 02/07/2015Tạp chí Khoa học Công nghệ Xây dựng số 2/2013
Wind speed profiles: comparative study of different wind codes (pp.3-11)
Dr. Vu Thanh Trung, Eng. Nguyen Quynh Hoa
For wind study, a precise knowledge of the characteristics of the approaching wind is necessary. The approaching wind characteristics are largely controlled by the roughness of the upwind fetch over which it had blown. The way that wind speed profiles of the approaching wind is being taken care of by different wind codes can be very different. This paper presents a comparative study about wind profiles according to different wind codes and a set of wind profile (10 minute mean and 3 second gust) is proposed for Vietnam wind code.
Progressive collapse of multi-storey monolithic RC frames in dynamic nonlinear analysis (pp.12-17)
Dr. Cao Duy Khoi
Under specific impacts as progressive collapse, dynamic effect has the significant influence. However, such influence has not been studied thoroughly. The researching object of this article is the “cast-in-situ reinforced multi-storey frames subjected to sudden loss of column in the 1st floor”. For dynamic effect evaluation, dynamic load factor (Kdv) is calculated by nonlinear dynamic analyses for frames with different numbers of floors.
Analyzing results from field constant head permeability tests (pp.18-23)
MEng. Nguyen Huy Long
Permeability coefficient can be determined by different testing methods such us laboratory or field tests. In the field permeability tests, the natural soil conditions such as density, undisturbance, saturation of the soil, etc., are almost unchanged that gives the test results more appropriate to the actual condition. This paper presents the actual field constant head permeability tests and their analyzed results.
Ultra high performance concrete using the combination of silica fume and fly ash available in Vietnam (pp.24-31)
MEng. Nguyen Cong Thang, Dr. Nguyen Van Tuan, Prof. Dr. Pham Huu Hanh, MEng. Nguyen Trong Lam
Ultra-high performance concrete (UHPC) is one of the promising concretes with a very high fluidity, a ultra high strength, a very low permeability, and an excellent durability. However, the high content of cement in this concrete, normally from 900 to 1000 kg/m3, can produce negative effect on both the cost and the properties of the products. Therefore, the use of mineral admixtures to replace cement in producing UHPC is a good solution in terms of technical, economic and environmental problems, and this will contribute to sustainable construction development.
This paper presents the preliminary results of using a combination of silica fume and fly ash available in Vietnam to produce UHPC. The results show that this combination improves both the workability and compressive strength of UHPC, which is very important for development and potential applications of this concrete in construction industry in Vietnam.
The study influence of Haiphong thermal power plants ash on compressive strength and waterpermeability of concrete in Vietnam humid climatic conditions (pp.32-35)
Dr. Pham Toan Duc
In 2009 Haiphong 1 thermal power plant with a capacity of 600 MW was officially put into operation but there has been no recruitment workshops for separating ash from coal ash mixture for reuse. Quality recruitment ash in a thermal power plant concrete depends on many factors such as the technological chain of power plants, technological lines become separated shop's products, the quality and origin of coal used for thermal power plants. Therefore, more research needs to evaluate a comprehensive recruitment ash quality and efficiency of nowhere to bring it before the line separating investment into the ash. Within the scope of the article, the authors introduce the results of his research while using ash recruitment Haiphong thermal power plant in concrete.
Determination of verticality of high-rise building using GPS with consideration of the building displacements (pp.36-41)
Dr. Nguyen Quang Minh, MEng. Nguyen Dang Hieu
This paper mentions to some issues in determination of the verticality of high-rise building using GPS. In determining the verticality of the high-rise building, the effect of oscillations and displacement to the GPS observation during the measurement is a very important factor which is not yet concerned so far in Vietnam. This issue is discussed and examined in this paper for the high-rise building project of Lotte Tower in Hanoi and from that a conclusion on the necessity of using GPS to determine the coordinates for the very top floors of the high-rise building is presented.
Establishment of interpolation formula for the elevation anomalous in the local topocentric coordinate system (pp.42-45)
MEng. Nguyen Xuan Hoa, MEng. Le Van Hung
When establishing the topocentric coordinate system for a building, beside the measurement of national coordinates (VN-2000) to the datum point of control network, it is necessary to transfer the elevation to some points GPS by differential leveling in order to determine the anomalous elevation serving as a basis for establishment of interpolation formula. For a region with average area and relatively flat terrain, a bilinear function can be used for interpolating anomalous elevation based on common points.