Applied Mechanics and Materials Vols. 477-478

Abstract: At first, mechanical behaviour and failure pattern are analyzed in the condition of full bond (with no relative deformation) with I-section and RC beam, and influence of unloading degree in this text, the theory formula of bearing capacity correspondence to failure pattern is erected, the appropriate simple calculate in engineering employ are submitted. In the condition of large the initial reinforcement ratio and the advice is given that strengthening by externally bonded and anchored I-section steel is avoided. Besides, in the condition of considering of bold-slid, the formula of interface stress is erected. Base on the relative slipping effect, the theory formula of additional moment that is derivable from slid action, and the influence of the thickness of glue, unloading degree the ratio of I-section steel to additional moment is discussed.

Abstract: Fire-resistance performance of slabs can be improved if the slab strengthened by carbon fiber sheet bonded with inorganic adhesive instead of organic epoxy adhesive with low softening temperature. However, Fire-resistance performance of the strengthened slabs is not understood fully. Considering this issue, finite element analysis is done. Stating from building valid model of finite element, computing results are compared with experimental results, and rationality of the model is verified. Then plenty of parameter analysis is done. Effect of some parameters, such as range of carrying capacity increase by sheet, reinforcement ratio, load ratio to carrying capacity and thickness of slab, on fire-resistance performance of the strengthened slab is analysis. The results demonstrate that thickness of slab is the main factors influencing fire-resistance performance of the slab strengthened by carbon fiber sheet bonded with inorganic adhesive. While, range of carrying capacity increase by sheet, width of section and load ratio to carrying capacity have little influence on it. Slabs, strengthened by carbon fiber sheet bonded with inorganic adhesive, and protected by Thick-typed Fireproof Coating, perform good fire behavior.

Abstract: In the action of bending load and axial compression, the deflection of the beam presents character of geometry nonlinear. For the thin-walled carbon fiber laminated box beam column, the beam deflections not only relate with load but also with the ply angle of layer, span width ratio. By using the method of numerical, this paper analyzed and summarized the beam deflection variation with the span width ratio, ply angle, the axial compression ratio for the simply supported laminated box beam column under the axial compression and bending load.

Abstract: In engineering applications the uncertainties of the structural parameters are inherent and the scatter from their nominal ideal values is in most cases unavoidable. These uncertainties play a dominant role in structural performance and the reliability-based design optimization is a useful method to assess the uncertainty influence. Compared to the basic deterministic-based optimization problem, the latter considers additional non-deterministic constraint functions and will provide the structure more safety. This paper proposed a Fourier orthogonal neural network method to the structural reliability analysis and reliability-based optimization considering uncertainties, the main aim is to minimize the weight of the structure under certain reliability constraints, and to obtain economic benefit meanwhile ensure the safety of the structure.

Abstract: Focusing on the Zhengzhou East Railway Station, which is the larges railway staton in China at present and has the characteristics of bridge-station combined structure. The vibration responses of waiting room floor and business floor caused by high speed train loads are measured and calculated. Then the vibration comfort was evaluated by the code of ATC (1999). The calculation and analysis results showed that: (1) the vibration of waiting floor and business floor under crowd get up loading is small, which can satisfy the comfort demand; (2) the vibration of waiting floor and business floor under high speed train load is bigger because the waiting floor and business floor is more flexible; (3) the vibration comfort under high speed train load can satisfy the demand of relevant code.

Abstract: Modal identification technique is an effective measure for building materials health diagnosis, structural optimization design and safety assessment in structural engineering field. The time-domain method can only use the response signals to identify the modal parameters under ambient excitation, which became a wide concern topic in recent years. According to the points above, the theories of random decrement technique, complex exponential method and time-series method are presented. The random decrement technique is combined with the other two methods to become joint algorithms. A numerical simulation model is constructed to verify the feasibility and validity of the two joint algorithms.

Abstract: Structural parameter identification is a significant technology to show certain characteristics and material damage of earthquake resistant structures or building materials in structural engineering and seismic engineering field. ARMA time-series method is belonged to time-domain method. ARMA time-series method for estimating the modal parameters of structure is presented in this paper. In order to verify the accuracy of the method, analytical simulation studies are performed for a frame structure model on the basis of simulated data under white-noise excitation conditions. And the results are analyzed and discussed. The research demonstrates that ARMA time-series method can effectively identify the modal parameters.

Abstract: In order to clear the influence of carbon fiber reinforced polymer (CFRP) on the bearing capacity of reinforced concrete beams, tests of three reinforced concrete beams strengthened with CFRP are carried out. Experimental result shows that CFRP can effectively increase bearing capacity of flexural member, and can restrain the development of crack. Cracking load, yield load and ultimate load are significantly increased. At the same time numerical simulation is done; it is good agreement with experimental results.

Abstract: Based on the probability reliability theory, this paper proposes a modified consistent mode imperfection method, which fits the integral stability analysis of single-layer reticulated shells with the initial geometric imperfections. Nearly 1000 elasto-plastic load-deflection overall processes of four different rise-to-span ratio for Kiewitt-8 single-layer reticulated shells are analyzed by using the random imperfection mode method, the consistent mode imperfection method and the modified consistent mode imperfection method respectively. The study shows that the random imperfection mode method can assess the influence of initial geometric imperfections on structure stability more scientifically, but the calculation is quite large. By using the consistent mode imperfection method, the buckling load is not sure to be the most unfavorable, and the degree of reliability couldnt be ensured effectively. The modified consistent mode imperfection method can gain the buckling load which meets the requirement of probability reliability with less calculation. It can also assess the stability performance of single-layer reticulated shell structure more reasonably and safely.

Abstract: As one of the main stress components of energy-saving structure system, grid frame shear wall was chosen as the main research object. The low cyclic loading tests were applied to test the mechanical properties of three kinds of grid framework with aspect ratios 0.69, 1.1 and 2.75. Based on the analysis of failure mode, bearing capacity, ductility, and energy dissipation capacity and so on, the factors affecting on the seismic performance of the grid frame shear wall were discussed.