Applied Mechanics and Materials Vols. 477-478

Abstract: The heat-fluid coupling method is introduced to perform the thermal analysis of a pipe cooling system in mass concrete structures, to precisely simulate the distribution of temperature. The heterogeneous mesoscopic mechanical model based on the random aggregate-interface-mortar three-phase concrete is established. And numerical experiments of concrete water process are taken with a three-phase heterogeneous model, so as to actually simulate the whole crack propagation process considering non-uniform temperature distribution, and then explore the crack propagation law, generating mechanism and comprehensive understand the factors and process of the concrete temperature cracks under complex conditions.

Abstract: Polypropylene fiber reinforced concrete (PPFRC) is such a composite material that can enhance and improve the mechanical property of the concrete with small mixing amount of polypropylene fiber. By taking into consideration the heterogeneous characteristics of materials at meso-scopic level, the initiation of micro cracks, the propagation and the coalescence between cracks have been simulated in PPFRC specimens with different amount of addition under three point bending load. The numerical analysis shows that there is only little difference on failure pattern and path between PPFRC and plain concrete. However, polypropylene fiber can reduce or even eliminate plastic cracking and can help to control crack expansion and it could be identified that most fibers in PPFRC are broken under tensile stress. Furthermore, polypropylene fiber plays different roles during the substrate plastic shrinkage and hardening stages. The toughness and deformability have been significantly improved with mixing of polypropylene fibers but the rupture strength is almost the same. Meanwhile, it also could be found that, with the increasing amount of polypropylene fiber, the deformation ability and the toughness have been increased, but the strength is kept almost the same, while the elastic modulus is actually decreased.

Abstract: This paper focuses on the performance evaluation of long span cable-stayed bridge. Pushover method has been compared with RHA method to verify its validity. A specific bridge has been calculated by pushover analysis method using several different lateral load patterns. With four typical seismic analysis methods on the structure, the pushover analysis capacity curves have been compared with the RHA’s. It is demonstrated that the pushover method is accurate enough to be used in Engineering.

Abstract: In this paper, three-tower cable-stayed bridge Jinan Jianbang as the researched object, is to built to two models of the bridge with piles and without piles using the finite element software , and is made dynamic characteristic analysis. Meanwhile it is compared the control force of and the elastic response spectra and time history analysis under different conditions.At the same time ,bridge model without pile is excitated by multi-point for traveling wave effect analysis. The results show that pile-soil effects make more greater impact on forces of large span structures, and traveling wave effect on the adverse effects of large-span cable-stayed bridge shoule be considered in the seismic design.

Abstract: The seismic damage of nonstructural system is severely, and has affect escaped from building and rescue. Suspending system is the typical one of the nonstructural system. This paper investigated the seismic damage of suspending system in Lushan earthquake. Suspending system of many buildings are failure, especially for the hospital and gymnasium which is used for disadvantaged group and rescue. Moreover, design of suspending systerm is lack of industrial standards, so much attention should be paid.

Abstract: This paper introduces the seismic damage of nonstructural system under severe earthquake at home and abroad. Then seismic research on nonstructural system is little, and that does not match to severe damage, especially the nonstructural system cost high proportions of total price. Damage of nonstructural system has affected people in the life and property safety in the earthquake. Moreover, the paper pays more attention to ceiling system under seismic.

Abstract: Taking Jiashao Bridge as the research subject, this paper established finite element model by ANSYS to study random seismic response of multi-tower cable-stayed bridge. The results show that the constraint relations between tower and girder influence internal force at bottom of towers deeply, and the force of each tower is different. The vertical displacements in the midspan of girder are varied in different constraint relation. In addition, the effect of traveling waves on this bridge under excitation was analyzed, the results show that traveling wave velocity has an important implication on the seismic response of multi-tower bridge, and there are some regular relations between the response of structure and high traveling wave velocities.

Abstract: Seismic safety evaluation was commonly carried out using an equivalent linear method LSSRLI-1, proposed by Xiaojun Li in 1989, which greatly promoted the development of earthquake resistant engineering of China, for it solved the input problem of earthquake response analysis of building structures. The current situation of seismic response analysis for deposits is described first. Then, a series of deficiencies for the analysis program LSSRLI-1 found in the practice are represented. The exact solution based on the wave theory is used to verify the LSSRLI-1 results without iteration. Comparison show that LSSRLI-1 should be further perfected due to its deviation from exact values, especially when the soil is soft.

Abstract: In the process of seismic safety evaluation, engineers need ground motion parameters which may be obtained from different programs. For exploring the difference caused by different programs, 4 horizontal layer models of construction sites are established, and 3 earthquake waves are inputted. Results between SHAKE2000 and LSSRLI-1 indicate that there exists evident difference when the groundsill is weak. Soil profiles, inputting earthquake waves, and amplitude influence on the error of the programs. In the process of seismic safety evaluation engineers should take care of the error caused by using different programs. The error also demonstrates that equivalent linearization method have upgrade potential internally.

Abstract: The axial load-biaxial bending moment interaction model (N-M model) is developed based on the metal plasticity theory, and its reliability in structural analysis is evaluated. Employing CANNY program, linear and nonlinear dynamic time history analysis is conducted to a 32-story SRC structure. The dynamic responses are compared between N-M model and fiber model cases. The results show that N-M model can simulate well the dynamic response of the high-rise hybrid structures. Besides, N-M model has clear mechanical concept and is much simpler compared to fiber model, and the computational efficiency can be greatly improved by using N-M model.