Applied Mechanics and Materials Vols. 351-352

Abstract: This article mainly analyzed the load of fixed and movable pipe supports in the catalyst factory,then classified the load. A calculation was made using MIDAS/CIVIL software modeling. The results show that the bending moment and displacement are all the same in axial of movable and fixed pipe supports, and the axial displacement is influenced heavily by load. Fixed pipe supports are less affected by lateral load, but movable pipe supports are more affected by lateral load. The results can help us to design the pipe supports reasonably.

Abstract: Based on the high dimensional model representation (HDMR) and Monte Carlo simulation (MCS), this paper presents the improved method used to evaluate the failure probability of the system with multi-failure models. The HDMR is a general set of quantitative model assessment and analysis tools for capturing the high-dimensional relationships between sets of input and output model variables. Once the limit state function is defined by using the HDMR, the failure probability can be obtained by using the MCS without increasing computational efforts. The series and parallel system are considered in this paper, a numerical example is presented to demonstrate the efficiency and the accuracy of the proposed method. It is shown that the efficiency of the HDMR are both high in terms of series system and parallel system, the accuracy can be acceptable with respect to series system, and the accuracy can not be acceptable with respect to parallel system.

Abstract: Due to different structural form, surrounding environment and external force, the damage of Ancient Tibetan buildings reflects its own characteristics. In this paper, the damage types of ancient Tibetan buildings are classified based on fieldwork, and then the damage reasons are studied. The main failure modes of ancient Tibetan buildings are damages and deformations of timber components and walls, including cracking and deflection of beams, column cracking, Queti slating, decay and cracking of rafters and cracking in walls. The damage reasons of ancient Tibetan buildings can be attributed to three aspects: degradations of timbers, structural defects and long-term external forces.

Abstract: This paper discusses the feasibility of damage identification on simply supported slab bridge by the curvature mode. Firstly, the theoretical basis of curvature modal method for damage identification is introduced. Then, it simulated the structural damages by the use of three-dimensional finite element model, and used curvature mode to identification them validly. Based on the finite element simulation results, the following conclusions can be drawn: the decline of the structural natural frequency can be used to judge if the simply supported slab bridge is damaged. But the declined value is small, it is almost impossible to achieve in the scene, and it also can not be accurately positioning and quantitative; curvature model is very sensitive to the partly change of structure. It cannot be affected by the interference of the other plates, when the damage condition was identified on one plate of the simply-supported slab bridge even if that plate is adjacent plate would not affect it.

Abstract: Nine post-tensioned concrete (PC) beams were made and corroded by impressing direct current to them. The influences of different factors, such as the corrosion ratio of prestressing tendons, grouting condition etc., were taken into consideration. The failure modes and mechanism of corroded PC beams were investigated by monotonic loading tests. The experimental results showed that the higher the corrosion ratio of prestressing tendons is the lower the cracking, yielding and ultimate capacities of the PC beams will be. With the development of the corrosion of prestressing tendons, the characteristics of load-deflection curves of PC beams are no longer similar with that of uncorroded PC beams, but turn into that of reinforced concrete beams. The prestressing tendons will be easier to corrode for a beam with bad grouting condition, and the corrosion will lead to severe deterioration of the bond strength between concrete and prestressing tendons that will greatly reduce the stiffness of the beam.

Abstract: t is Founded that S_R can comprehensively reflect the general effect of the blasting vibration and the influences of Structural damage of vibration by structure dynamic characteristics. The computation and the analysis of 132 groups blasting vibration data indicates that probability of destroying of general houses by blasting vibration increases significantly when [S_R]5.5. And then the [S_R]5.5 is used as a supplementary of blasting vibration damage safety criterion standard of 2sd construction. On this basis, the unified security criterion of blasting vibration safety is initially founded through introducing the concept of P_rs of structures blasting vibration spectrum safety factor.

Abstract: The Chebyshev orthogonal polynomial with sample moments (the origin moments) were used to approximate the probability density function (PDF) or cumulative distribution function (CDF) of variable (CPA method). Three examples from observed datas of uniaxial compressive strength of a kind of hard rock were presented for illustrative purposes. The results show the PDF or CDF of rock variables can be accurately derived from CPA method with sample moments. The relative errors of estimation by CPA method is much smaller than that of TDF method (PDF fitted by some standard theoretical distributions). It is suggested that the presented method can be used in stochastic reliability analysis of rock engineering.

Abstract: Reliability analysis is an emerging field of structural engineering which is very significant in structures of great importance like arch dams, large concrete dams etc. The research objective is to design and construct a new method for the analysis of the system reliability of dam. The failure paths are searched out after failure mode and composite performance functions are set. Bayes formula and Cauchy-Schwarz Inequality are adopted to deduce the upper limit of failure probabilities in some failure modes that can obtain the failure probability of system of dam. A test example is given to verify this method. Compared with other conventional algorithm, this method has the strong points: more failure paths are considered and more safety methods are used to estimate the system reliability of dam.

Abstract: Early-age cracks on cast-in-place slab with ready mixed concrete is a widespread problem,which is also difficult to solve.A cracking instance of cast-in-place concrete slab is introduced. The causes of the cracks are presented from two aspects of theoretical and calculation analysis after the field detection, and the corresponding treatment scheme is proposed.Meanwhile, the corresponding precautions for early-age cracks on cast-in-place slab are suggested on three aspects:concrete material,construction and design. And the good effect has obtained in the subsequent construction.

Abstract: Under the consideration of radiation, convection, and evaporative cooling, simulating the effect of different curing temperatures (5°C,10°C,15°C,20°C,25°C,30°C) on the performance of concrete at early age. The results showed that curing temperature affected the early age performance of concrete greatly. Higher curing temperature improves the peak temperature of concrete members, and contributes to the development of the strength of concrete at early age, but elevated curing temperature will lead to higher cracking potential classification of concrete at early age.