Applied Mechanics and Materials Vols. 94-96

Abstract: A shear wall on frame structure is adopted in the structural design of the Daxian International Building. Nonlinear time and history analysis under rare earthquake occurrence is carried out to check the elastic-plastic angular displacement limits and to identify structural weaknesses. The structural model is modified to improve seismic performance and ductility of the building based on the calculated results. The process and procedure of the structural design can act as a sound reference for similar structural designs during ensuing engineering endeavors.

Abstract: The electromechanical impedance (EMI) technique, which employs piezoelectric ceramic (PZT) patches as transducers, is emerging as an effective and powerful technique in structural health monitoring (SHM). This paper presents a novel method to extract the damage-sensitive feature (DSF) for EMI-based SHM. Firstly, the concept of effective drive point (EDP) impedance was introduced briefly. Secondly, a novel DSF was proposed as the ratio of the active parts of EDP admittances before and after damages. Finally, the effectiveness of the proposed DSF was experimentally verified. The results show that the novel method provides a sensitive feature for EMI-based SHM

Abstract: Idea of element co-adaptation of construction ergonomics claims the elements of construction ergonomic system mutual fitness. Flexibility of construction system embodies the element co-adaptation. Flexible ergonomic principle indicates that construction system design and update must make the system to have and keep the function of fit in with and conversion of noise to meet the needs of flexibility of construction system. Principle of factors fit in with system expresses the relations between construction ergonomic system and its factors. The principle claims any one of the factors should co-ordinate the system, and that is the precondition of system flexibility. Principle of factors mutual fitness expresses the relations between the factor and factor of system. It voices that any one of the factors (and fine factors) should adapt to other ones and keep on the adaptation. The paper names the last two principles combined as “fit flexible principle” and proofs it by using system evolutionary equation through defining the conception of adaptable coefficient of factors. Findings of the research have corrected the ergonomic system design idea that based on cybernetics as well as the optimizing idea of construction resource that based on static thinking.

Abstract: An investigation was carried out on the behavior of concrete under both sulfate attack and mechanical stress. The specimens of concrete with/without fly ash were subjected to flexural load with a level of 0.2 and 0.4 of their initial strength and also immersed into a 10% sodium sulfate solution or water respectively. The bending strength of the concrete was tested at certain time intervals. The results indicate that fly ash could effectively relieve the deterioration of the concrete in corrosive environment; flexural load could accelerate the corrosion damage and that the development of concrete strength is related to the internal structure, hydration product and the interface between coarse aggregate and cement paste.

Abstract: There will emerge cracks or damage due to the action of rock pressure or its own shortcomings and low strength for the lining structure in tunnel or underground engineering, especially at the places of excessive bending moment and tensile stress because of bias pressure where concrete will be pull apart for the deficiency of strength even to cause leakage and durability insufficient. Conventional maintenance and reinforce methods are time-consuming and laborious, and the effect is also not ideal. It is simple, timesaving and having a significant and lasting effect to use carbon fiber reinforcement method. This paper studied structure’s failure mechanism and on the basis of that the principle of fiber-plate reinforcement from the angle of structural plastic development, then studied the improvement of structure’s mechanical character and the change of design calculation method for single section of underground structure with carbon fiber plates by using the research method of plane-strain. At the same time, the typical model of integral failure for single section was analyzed and the calculation method and formulae of bearing capacity and reinforcing steel bars were deduced, which remedied the shortfall in the design specification for concrete structure. In the end, by comparing the calculation results of structure with fiber plates and that with not fiber plates based on engineering example, the conclusion that structure’s bearing capacity and capability of resistance to deformation had obvious improvement was obtained.

Abstract: In this experiment, three beams are chosen from a used hollow slab bridge, and one of them is reinforced by planted steel bars in old pavement and others are left intact or cleared away from old pavement for comparison with the first one through static lastage pressing experiments. The research results show that planted steel bars between pavement and beam can enhance the connection, upgrade rigidity and change the flexural behavior .The study may also be taken as a reference of the bridge reinforcement’s research.

Abstract: Using finite element software, the analysis model of semi-rigid base pavement with voids is established. Variation of deflection under load of Falling Weight Deflectometer (FWD) is studied and the reference critical value is obtained to determine whether there are the voids. According to analysis of the deflection basin data under different location, the identification method for the void location of semi-rigid base pavement is established. The field test shows that it is feasible to use this technology in void identification for semi-rigid base pavement.

Abstract: In the case of small increase of cross-section, concrete column strengthened by circular steel tube can increase the bearing capacity greatly as well as ductility. This has resulted in engineering welcome. This paper studied the common work performance of reinforced concrete column strengthened by circular steel tube in three different conditions test of axial compression. The results show that outsourcing steel and core column can be achieved interaction. By strengthening, it can improve the load capacity of the concrete column as well as ductility. With the increase in initial load, although it has little effect on the bearing capacity of reinforced columns, it can affect the ductility to some extent. This paper can provide experimental basis for engineering applications.

Abstract: With the continuous development of national economy and the construction technology, a lot of large-span spatial structures with unique form and complex construction are emerging. The health monitoring system that mainly used in bridge structure is applied in large-span spatial structures gradually. Parameter identification and damage alarming are the core technology of health monitoring. In this paper some structural modal parameter identification methods based on ambient excitation are introduced. Finally, for large span structures with characteristics of low-intensive modes, the response data based on large span structures for modal parameter identification method was summed up, and the critical issues for further research in this field are also presented.

Abstract: A new reinforcement technology with prestressed helical rib steel wire bonded in sawed grooves in the concrete cover is presented, based on the deficiency of the presented reinforcement methods. Four test beams NSM prestressed steel spiral ribs are tested in this paper. The stiffness expression of the reinforced concrete beams in different stages is derived and the stiffness formulas of the reinforced concrete beams are gained, based on the general deformation principles of reinforced concrete beams and the characteristics of the reinforced concrete beam NSM prestressed steel spiral ribs. The results of the calculation and the experimental results show good agreement. It shows that the reinforced concrete beam NSM prestressed steel spiral ribs can effectively delay the development of cracks, reduce the component deformation and increase its stiffness. The results provide an experimental basis for the reinforcement method in practical engineering applications.