Applied Mechanics and Materials Vols. 166-169

Abstract: This paper studies the mechanical behavior of Carbon-fiber-reinforced polymer (CFRP) in one-way reinforced concrete slabs, and the relation of CFRP and steel bar strain under the uniformly distributed load. Based on the theoretical analysis of the constitutive relationship, the analysis calculation model was built by using the ABAQUS software. Data analysis demonstrates that under the same conditions the load-strain curves of CFRP and steel bar are similar, which indicates that the mechanical cooperation performance of CFRP and steel is mutually beneficial. The load-strain curve of CFRP and steel bar is linear before the steel bended, and the curve is approximately linear after the steel bended. In the reinforced stage, the curve is again linear and the strain rate of the CFRP and steel bar increases constantly with the increase of load. This result is valuable for related studies.

Abstract: This article makes finite-element simulation and analysis on a reinforced two-way curved arch bridge by means of ANSYS, a tool of finite element numerical analysis. Through comparison with the testing results after reinforced, it validates feasibility and reasonability to analysze a reinforced two-way curved arch bridge using a physical unit of ANSYS. On basis of this, it brings forward an idea of optimization design and researches the real two bridges for optimization of reinforcement using ANSYS analyzing and mathematically statistical method. Through effects after and prior optimization, it demonstrates necessity for optimization design of reinforcement and attains some significant conclusions which provide theoretical basis to direct production in the future.

Abstract: Through the ANSYS finite element method, the seismic performance of frame columns reinforced with wing walls has been analyzed, indicating that the wing wall reinforcement can effectively improve the lateral stiffness and remarkably increase the bearing capacity of columns. With the wing wall reinforcement, the envelop area of the column’s hysteresis curve increases, and the bearing capacity improves, however, the shrinking phenomena of the curve suggests that the ductility of the section reduces. When the centerline of the additional wing wall coincides with that of the original column, the hysteresis curve inclines to be full, thus advising overlapping the centerline of the wing wall with that of the original column.

Abstract: To study the anchorage performance of the inorganic post-installed RC flexural members in flexural test, this paper simulates the stress state of the inorganic post-installed RC flexural members in practical projects. Through cyclic loading test, the anchorage performance of the inorganic post-installed RC flexural members in the bending tensile conditions is checked. This paper studies the anchorage performance of the post-installed steel at the state of bending tension, such as: adhesion stress, bond-slip relationship, the load carrying capacity, deformation behavior of the flexural member, and compare with those of normal member. The result indicates that with anchorage length of 20D in flexure member, the load carrying capacity of the inorganic post-installed reinforced concrete is apparently worse to those of normal members under repeated loading test; In case that anchorage length is invariable, load carrying capacity can be significantly enhanced through improving the concrete strength level. The anchorage zone is easily damaged, and the steel is easily slipped, which result in the decrease of the load carrying capacity, so some measures must be taken if inorganic adhesive powder is used in practical projects.

Abstract: This paper presents the results of the experimental investigation on the shearing performance of beams strengthened with steel wire-polymer mortar. The numerical results by finite element method are compared with experimental results. A total of three rectangular doubly RC beams were constructed, strengthened and tested to failure. A new convenient method to measure elongation of steel wire was proposed. Two models, named separated model and composite model respectively in software ANSYS, are used to analyze the beams. In separated model, strains of longitudinal steel bars and stirrups are in good agreement with the test results, and strains of longitudinal steel bars by composite model are also in good agreement with the test results, while stirrups strains are not, but both of steel wire deformations obtained by ANSYS analysis models are slightly different with tests results. Strengthened beams increased ultimate capacity, delayed the crack occurs and crack development. More closer and disorder cracks distribute in the strengthened beams than the unstrengthened beam. Cracks in beams by ANSYS analysis models, comparing with test results, are not very obvious.

Abstract: The control methods used for free/shock vibration suppression are normally different from those used for forced vibration cancellation, because shock vibration is regarded as a type of transient vibration that is different in nature from steady-state forced vibration. However, both steady-state and shock excitations may occur in flexible structures, so there is a need to control both types of vibrations. To show the integration of the two different vibration control strategies, a hybrid control system based on adhesive strain gauges and PZT patches is proposed to construct a distributed resonant absorber and shock absorber together. The hybrid system is governed by a control arbitrator that decides which absorber should be active according to the different excitation conditions. The effectiveness of the integrated system is shown through simulation and experimental studies.

Abstract: Abstract: the paper introduces the advantages and disadvantages of the honeycomb core composite wallboard, and put forward various solutions on the problems that the honeycomb core composite wallboard on juncture place easily crack. According to the advantages and disadvantages, the optimal measures are to use CFRP paste connection joints. Tested by experiments, the results show that: for using cellular wall materials as new buildings retaining wall materials, CFRP enhancement processing juncture surface can effectively restrain cracks, and the results are ideal; for existing buildings retaining wall, gives suggestions about enhancement processing, and proves its feasibility.

Abstract: The present paper deals with the evaluation of the level of seismic vulnerability of a Reinforced Concrete (RC) building by using a Displacement Based Approach (DBA), in the context of a performance methodology, and by adopting the N-2 method, according to Italian seismic code NTC 2008. The RC building is located in Southern Italy in an area classified as high seismicity zone and designed, in the past, only for gravitational loads. During the evaluation phase the effect of masonry infills is considered by modeling with a non linear analysis all the panels considered in effective interaction with the structural frame. It is highlighted that in the examined case the masonry infills determine a worsening of the seismic behavior of the existing structure. So that it is illusory that by neglecting these panels a general beneficial effect would be obtained. Moreover in such case the neglect of these panels would have guided to a retrofitting strategy which is completely different and would have not answered to the real needs of the structure. The correct evaluation of the seismic response is finalized to the seismic retrofitting by using a traditional strategy, designed through a displacement based approach, for reducing the displacement demand on the existing structure. The adopted retrofitting strategy is represented by steel braces with steel reinforcement elements for the columns. In the non linear model for these elements it has been considered their confinement action for the reinforced concrete columns. The vulnerability level of the structure and the Safety Factor (SF), defined as the ratio between the displacement capacity and the displacement demand, is calculated for the building before and after the seismic retrofitting.

Abstract: An experimental program is designed to evaluate the performance of lightweight autoclaved aerated concrete masonry wall strengthened using ferrocement layers, in a sandwich structure, under in-plane compression and out-of-plane bending. The 25 mm thick ferrocement mortar is reinforced with steel welded wire mesh of 1 mm diameters at 15 mm spacing. Different types of shear connectors are used to evaluate their effect on failure loads. The effect of different design parameters on the wall strength are considered including wall thickness, mortar strength, and type and distribution of shear connectors. A total of 20 prisms are tested in compression and 5 prisms are tested under bending. The proposed ferrocement strengthening technique is easy to apply on existing wall system and results in significant strength and stiffness enhancement of the tested wall specimens.

Abstract: Experiments on flexural behavior of strengthened pre-damaged reinforced concrete beams with CFRP and those exposed to seawater for different time have been carried out. By comparison, the rule of seawater effecting on failure modes of beams, fissure condition, strain development and flexural capacity, and so on have been studied. The results show that reinforcement treatment on the mechanical damaged reinforced concrete beams with bonding CFRP can effectively improve their flexural capacity and stiffness, and constrain the development of cracks. With the extension of time under seawater environment, although performance of pre-damaged beam strengthened with CFRP is influenced significantly, the strengthening effect is still more reliable.