Advanced Materials Research Vols. 446-449

Abstract: The numerical analysis method is applied to simulate the whole process of bending. Keeping the section dimensions and the types of loads constant in prestressed concrete hollow slab with mid-strength spiral-rib steel wire, strength of concrete, strength of steel bar, reinforcement ratio, span-depth ratio and stretching control stress are analyzed and compared. The influence of strength of concrete, strength of steel bar, reinforcement ratio, span-depth ratio and stretching control stress on deflection-span ratio under standard load of prestressed concrete hollow slab is discussed by numerical simulation.

Abstract: The paper discusses the strain of high-strength concrete (HSC) at peak compressive strength for a wide range of compressive strength. A large volume of selected experimental data has been collected from existing literature and then analyzed. Particular emphasis has been given to studying the effects of concrete compressive strength and the types of coarse aggregate on the strain of HSC at peak compressive strength. The adequacy and applicability of the existing models for predicting the strain of HSC at peak compressive strength has been critically examined, and a new empirical model is proposed to cover concrete strength up to 125 MPa. The new empirical model seems to perform much better when applied to the published experimental data on normal weight concrete over a wide strength range.

Abstract: The technique of linking the SEM (Scanning Electron Microscopy) photographs taken around the interfacial transition zone area is applied to observe the development of hydration products for aggregate and paste at the different curing ages. This research first chooses the aggregate with clay properties not containing the calcium ion, and then observes the hydration products (such as CH, C-S-H) of calcium ion on the aggregate. Finally it assesses if the aggregate will produce ion exchange with cement and generate the hydration products. The very small samples to be observed are taken from the concrete compressive test specimen and must include both aggregate and paste. They are wiped with alcohol to have better pictures before shooting SEM. Initially, the interface of aggregate and paste is sought using 2000x magnification. However, the hydration products on either side of the interface with a range of 50 μm are observed using 10000x magnification. From the results, it is found that aggregate has not interacted with cement paste to produce hydration products and the bond stress of aggregate and paste is controlled by hydration products of paste.

Abstract: Based on the study of the influencing law of decision point to cost in the construction process, this paper analyzes the relevance of decision procedure and project cost, establishes integration cost dynamic model of construction project. Based on the model, computer aided decision system can be developed for the cost control of construction project. If the system is applied in the construction practice, overall, whole process and dynamic control of construction project cost can be implemented.

Abstract: Through orthogonal test, the main influencing factors to the ultimate bearing capacity, ductility and energy consuming ability of L-shaped concrete-filled rectangular composite steel tubular columns are studied. Research results show as follows: the most important factor in deciding the ultimate bearing capacity is the steel tube wall thickness; the most important factor in deciding the ductility factor is the steel tube wall thickness; the most important factor in deciding the equivalent viscous damping coefficient is the strength classes of concrete. At the same time the best level combination of these factors are got.

Abstract: The paper presents an experimental investigation on the structural performance of high strength cold-formed steel angle connection stiffened with U-bracket. A total of 18 sets of specimens were tested using different U-bracket configurations. The parameters of the U-bracket studied were the width of the web and the length of the flanges. The behaviour of the connection under load was observed and the failure mode of the connection was identified. It was shown that biaxial deformation occurred in the U-bracket. It was also demonstrated that the capacity of the connection of angle and U-bracket was 4 times the capacity of plain angles. Results showed that it was more conservative to estimate the strength of the connection by taking the total elastic capacity of the sections. It was more effective to use U-bracket with a 40mm web and 15mm long flanges with the 50mm width angle connection.

Abstract: As a debris detention structure, small arch dams have some characteristics of small size, big storage capacity, and economic compared with gravity dams In this paper, according to the work environment and force behaviors of debris detention structure, adopting Trial-load Method, and only considering the conditions of radial deformation compatibility at arch crown, a simplified method is derived, which is suitable for the calculation of small-scale debris arch dams. Examined by calculating an example, this method is simplified, and convenient to programmed, and easy to be mastered by engineering and technical personnel for debris detention structure design and calculation, and calculation accuracy can meet the project requirements.

Abstract: This paper made a research into each performance index of basalt fibre strengthen SBS modified asphalt mixture by using two kinds of gradation, which are AC-20C of mid-surface and AC-13C of upper layer. And compared and analyzed with the same gradation of carbon fiber strengthen SBS modified asphalt mixture. The results showed that compared to carbon fiber strengthen SBS modified asphalt mixture Conbasalt , basalt fibre strengthen SBS modified asphalt mixture is equivalent on water stability and fatigue resistance,etc. It is relatively weak on low-temperature crack resistance. But it has decided advantage on high temperature stability.

Abstract: The wave velocity analysis is a kind of popular geophysical method. These years it is also used in structural damage identification which is discussed in this paper. This method is used to detect the interior damage of structure and is verified to recognize the damage effectively. The expression of the vertical and horizontal velocity is deduced and the wave velocity function curve is drawn according to velocity variety rule. The two dimensional and three dimensional wave field figure is drawn according to the wave velocity analysis and it shows the distinguish between the damaged and integrated structure. We can see the change of the wave shape and velocity and we can identify the damage in terms of the velocity variety rule. So the method introduced in this paper is verified to be a pontential way to identify the structural damage.

Abstract: A new composite structure system is proposed in this paper to suit the demand of building energy conservation and heat preservation. Based on the low reversed cyclic loading test, the non-linear finite element (FEM) analysis model of composite shear wall is established by ANSYS so as to study crack status, stress variation characteristics and failure process under the action of horizontal loading. The results of ANSYS finite element analysis show good agreement with the test results.