Advanced Materials Research Vols. 446-449

Abstract: As the characteristics of high precision and non-contact measurement, digital photogrammetry technology is widely applied to displacement engineering measurement. On the basis of digital photogrammetry theory and the digital image processing technology, the main work of this paper is to find a method on displacement measurement method based on digital image which includes the key technology of feature points coordinates extraction from digital image and the algorithm of displacement measurement.

Abstract: In the present paper an experimental study has been performed on a masonry building prototype and some preliminary experimental results are illustrated for analyzing the structural behavior of a masonry building prototype subject to harmonic forces of different intensity. The physical model used for the laboratory test is a two-story masonry building characterized by a regular floor plan. The structure test is subjected to a harmonic force input supplied by a vibrodyne. The experimental results are aimed at characterizing the dynamic response of the masonry building subject to harmonic forces in order to describe the bahaviour of the masonry building under the predominant actions of a seismic input.

Abstract: Bolt connection is a usual connection in power transmission and power transformation steel structures, and preservative treatments such as rust removal and galvanization are adopted to protect the bolts. In order to investigate the influence of hot-dip galvanizing on the tensile strength of bolt, common strength bolts and high strength bolt produced in four factories were tested to gain tensile strength. The results indicate that hot-dip galvanizing may reduce the tensile strength of bolts, and galvanizing technics of different factory have difference influence on the tensile strength of bolts.

Abstract: Application situation of optical fiber strain sensor used in bridge structure state monitoring is detailed introduced in this paper, two bridges which optical fiber strain sensor is adopted in construction stage stress monitoring and long-time stress monitoring in our country are introduced as example. According to the theoretical analysis of structures, the strain monitoring locations are selected. The composite technology between optical fiber strain sensor and concrete is researched. The installation technology and protect method between optical fiber strain sensor and steel girder are extracted, and advanced acquisition software is explored. Finally, the application foreground of optical fiber strain sensor is discussed. The research result indicates that the optical fiber strain sensor is extraordinary suitable for state monitoring of bridge structure because it has the merits of light structure and reliable performance.

Abstract: Today there is an urgent need for effective monitoring whether for old buildings or new ones. While conventional early warning system for real-time monitoring is based on safety factor, this paper proposes a new reliability-based framework to monitor the safety of RC buildings probabilistically. The framework includes modeling resistance, predicting probability distribution of load effect, calculating reliability and setting reliability index threshold. The in-situ test data enables to update the resistance model through a Bayesian process. Meanwhile, the observed monitoring data predicts the probability distribution of load effect. FORM is used to calculate the reliability because the limit state function for real-time monitoring is linear and simple. This study shows that the reliability-based early warning system is of more scientific sense in quantifying the safety and may be applied to many engineering fields.

Abstract: Ram-compaction gravel pile with end expansion is widely adopted in the treatment of silty clay foundations. In this paper, the bearing properties of rammed gravel pile reinforced foundations and soil between piles were investigated by use of static load tests and heavy-duty dynamic penetration test. It is demonstrated that the settlement curves (P-S curve) of ram-compaction gravel pile with end expansion reinforced foundation and soil between piles were monotonic, without turning point being observed. With the increases of pile length, the bearing capacity of pile increases. According to the experimental results from heavy dynamic penetration tests and static load test, the strength of soil between piles is improved, which also have effects on the elimination of the uneven settlements. Comparison the results between heavy-duty dynamic penetration tests and over-heavy dynamic penetration tests shows that the later one is suitable on testing of the soil properties between piles. In addition, from in-situ measurements of uplift deformation of different depths, it is found that uplift behavior occurs with depth more than 0.5m, whit largest uplift value of 21cm. The result provides a reference for the design and construction of rammed gravel pile reinforced foundation.

Abstract: Transverse free dynamics of a beam-like nanostructure with axial load is investigated. The effects of a small size at nano-scale unavailable in classical mechanics are presented. Explicit solutions for natural frequency, vibration mode and transverse displacement are obtained by separation of variables and multiple scales analysis. Results by two methods are in close agreement.

Abstract: In consideration of the uncertain factors, a hyperbolic cooling tower with initial geometrical imperfections is studied by the PDS module in ANSYS. Contrastive analysis is made on stress, internal force, displacement and failure probability of cooling tower shell. It is indicated that the value of Mx and Ty is sensitive to the initial geometrical imperfections, and the failure of shell in imperfections increase in large. On top of this, the non-local cooling tower shell strengthened with FRP is found to solve the insufficient capacity, which is proved to be feasible. Lastly, the reliability analysis and design of tower shell strengthened with FRP are also carried out. It is proved that the probability design of strengthened shell can assure structure to meet the requirement of target reliability.

Abstract: The purpose of this study is to investigate the ultimate behaviors of aluminum alloy bolted connections assembled with four bolts. Specimens for single shear bolted connections were tested and finite element analysis based on this test results was conducted. The validity of finite element(FE) analysis for predicting the structural behaviors such as ultimate strength, fracture mode and curling(out-of-plane deformation) occurrence was verified through the comparisons between test results and FE analysis results. It is known that the curling resulted in sudden strength drop. Moreover, FE models with free edge and restrained out-of-plane deformation for curled specimens are analyzed additionally, therefore, the influence of curling on the ultimate strength; strength reduction ratio is estimated.

Abstract: The experiment of post-embedded RC bending members with inorganic anchoring material and integral casting RC member under repeated load is conducted for the parameters with anchorage depth(15D,20D) and concrete strength grade(C20,C30). Comparing and analyzing the experimental phenomenon and data, the failure mechanism, anchorage behavior, the bearing capacity and seismic behavior of these members.