Applied Mechanics and Materials Vols. 501-504

Abstract: In order to investigate the feasibility of reinforcement transformation schemes for actual engineering, Combined with the characteristics of the project, the reinforcement transformation designs of the roof beams is carried out, three kinds of reinforcement transformation design schemes are put forward, they are carbon fiber reinforced polymer strengthening, internal prestressing strengthening and external prestressing strengthening. The external prestressing reinforcement scheme is selected after comparing. Numerical simulation analysis of the reinforcement system is done by ANSYS software, and nonlinear finite element model of simply supported beam with crack is built, through analysis deformation, cracks and stress distribution of reinforced beam are obtained. The results show that the using function of beam is improved obviously. The rationality and feasibility of this reinforcement scheme is validated. These can provide references for reinforcement transformation of similar existing buildings.

Abstract: The old building was saved, protected and transformed with the original technique and measure. After the structure reliability of old building passed to test and evaluate, the architectural function was redesigned, old structure was reinforced and repaired. The structural integrity was strengthened using cement mortar and steel mesh to reinforce inner walls, adding cross walls, enclosure beam and seismic angle-steel. Without change the appearance of the building, a vierendeel steel truss was innovated, the loads of roof, truss and loft ceiling was transferred to small steel-concrete columns placed under truss support, not to walls. Vierendeel steel truss led to open space changed to the third floor within loft, the area increased twenty-six percent and met owner use at lower cost, results show good for ten years.

Abstract: A total of four two-way reinforced concrete slabs strengthened with three methods were tested. The four test specimens were one unstrengthened reinforced concrete slab (control), one slab strengthened with CFRP strips, one slab strengthened with steel sheets, and one slab strengthened with an innovative method of applying CFRP strips and steel sheets combination bonding to the tension face of the slab. The test results show the CFRP-Steel combination strengthened technique is a rapid and effective strengthening technique for two-way RC slab. The increase in ultimate capacities of CFRP-Steel combination strengthened slab is 221.1% over the control slab, 84.4% over the CFRP-strengthened slab, and 45.2% over the steel-strengthened slab. In addition, the CFRP-Steel combination strengthened slab exhibited superior ductility than the CFRP-strengthened slab.

Abstract: An attempt was made to replace the commonly used Fiber Reinforced Polymer (FRP) with aluminium alloy in NSM technique. This paper presents experimental investigation of interfacial bond behavior between NSM aluminium laminates and concrete structures. Aluminum laminates were mounted into premade slit of concrete with epoxy resin. Test results show that both maximum applied force and ductility of NSM reinforced specimens can be effectively improved by increasing bond length and width of aluminium laminates, whilst almost no change was found in average bond strength at the same time. Besides, the loaded end slip of specimen, corresponding to the maximum applied force, was mutually influenced by bond length and width of aluminium laminates. Furthermore, the measured strain distribution of aluminium laminates along the direction of bond length of specimen was found to be similar to that of FRP in NSM technique.

Abstract: In the analysis of engineering structures are usually adopt the method of fixed value, that is the practical engineering structure under load and the performance of materials used by structure shall be treated as a constant value.But, in fact, the structure of geometry size, bear the load, material parameters,computing model and so on are affected by various factors. In order to more accurately reflect the reliability problems of reinforced concrete structures, this paper, the factors above will be regarded as random variables, combining the basic theory of reliability design, through the probability analysis, in normal uselimit state reliability of reinforced concrete structures for example analysis of the influence of related parameters on the structural reliability.

Abstract: The performance function of large-scale complicated engineering structure is always highly nonlinear and implicit, and its reliability needs to be evaluated through a time-consuming Finite Element method (FEM). A new method, Gaussian process classification (GPC) dynamic response surface based on Monte Carlo Simulation (MCS) was proposed. Small training samples were created using FEM and Markov chain. Then, the most probable point (MPP) is predicted quickly using MCS without any extra FEM analysis. Furthermore, an iterative algorithm is presented to reduce the errors of GPC by using information of MPP to improve the reconstructing precision constantly. Then, Monte Carlo method combined with GPC surface is applied to get the probability of failure. Several examples results demonstrate the efficiency and robustness of the proposed method, compared with the results of common reliability methods.

Abstract: Autocrane has strict requirement for the bearing capacity of operation site during the process of lifting and transferring. To evaluate the intensity stability of operation site, the detailed analysis to ultimate bearing capacity of operation site must be carried out and find out the sensitivity factors which influencing the bearing capacity of operation site. In this paper, based on the analysis of computation pattern of ground bearing capacity, the ultimate bearing capacity is deduced through considering the shearing strength of superstratum under circular load ground. Simultaneously, based on single factor sensitivity analysis method, the sensitivity expression of cohesion force, internal friction angle and superstratum thickness to limiting bearing capacity is analyzed and calculated, and the influence regularities of the ultimate bearing capacity of operation site, due to the sensitive parameters, is discussed.

Abstract: In order to predict the failure probability of a complicated structure, the structural responses usually need to be estimated by a numerical analysis such as finite element method. The response surface method could be used to reduce the computational effort required for reliability analysis when the performance functions are implicit. However the conventional response surface method is time-consuming or cumbersome if the number of random variables is large. This paper presents a Legendre orthogonal neural network (LONN)-based response surface method to predict the reliability of a structure. In this method, the relationship between the random variables and structural responses is established by a LONN model. Then the LONN model is connected to a reliability method, i.e. first-order reliability methods (FORM) to predict the failure probability of the structure. Numerical example has shown that the proposed approach is applicable to structural reliability analysis involving implicit performance functions.

Abstract: The landslide disaster tends to cause safe hidden trouble to the normal operation of the pipeline and pipeline is likely to take place accident and get failed under the action of a landslide. According to the theory of winkler, in the condition of pipeline landslide, the mechanical model is established and calculated the stress distribution under different landslide scale. According to the calculation result, the dangerous section of pipe is obtained. Based on the pipeline's own strength and pipeline working stress in the landslide, the limit state equation of the pipes is set up by using the third strength theory. Finally according to the distribution of stress and strength, the pipeline reliability index and failure probability are obtained by means of the first order second moment method improved. The achievement of this paper has great value .to the buried gas pipeline risk assessment. Key words: landslides; The third strength theory; The first order second moment method; Reliability index; Failure probability

Abstract: The western region of Jilin province is one of the areas with the most serious saline soil, which is the type of inland soda salt. In order to study the damage law of concrete under the condition of long-term erosion by the soluble salts in saline soil or groundwater or saturated salt water, three groups of salt solution, Na₂SO₄, NaCl, NaHCO₃ solution, were made according to the content of soluble salts in saline soil of Daan city in spring, and water was as a comparison. The comparing tests of long-term immersion were conducted on the normal concrete specimens with the size of 40mm×40mm×160mm. The results show that there is little change on the appearance, mass and dynamic elastic modulus of concrete soaked in water. But for the concrete soaked in salt solution, the loss rate of mass changes from reduction to growth, the relative dynamic elastic modulus of concrete grows at first and declines later. Through analysis of electron microscope scanning, energy spectrum and chemical composition of concrete samples, concrete damage caused by salts includes chemical erosion and salt crystallization damage. Na₂SO₄ mainly influences the dynamic elastic modulus of concrete, NaCl mainly influences the mass of concrete due to its strong penetration, while NaHCO₃, ranking between the two salts above, largely influences not only the mass of concrete, but also the dynamic elastic modulus of concrete.