Applied Mechanics and Materials Vol. 188

Abstract: In order to understand the soil-structure interaction, we were doing the excitation test about 1:4 scaled steel frame-raft foundation model in the soil bin. The test was through changing the stiffness of the superstructure respectively. We inputting Gaussian white noise measured vibration period, dynamic response with EL and Taft wave show the shock absorption effect of the soil. Finite element software sap2000 simulated rigid foundation on the dynamic response analysis on the steel frames. We found that there are some differences about the natural period, the upper structural stiffness greater the additional period is longer. Soil has a shock absorbing effect with the steel frame, the effect mainly come from the change of structure stiffness. Because of the soil-structure interaction, peak acceleration of the top storey is reducer when steel framework excitation on the soil bin than on rigid foundation, and peak displacement of the top storey is increased.

Abstract: A residential building, a brick/concrete structure built up in 1990s was used for many years. Since a deep foundation pit construction was being done in the north, the residents were worrying about the cracks in the building and its safety. Therefore, the following works were done such as the spot checks of the building engineering quality were done; the test and analysis were carried out over the cracks development after the foundation pit was backfilled, the influence assessment of the foundation construction under the mutual effects of pilings and anchor rods over the residential building structure was also conducted; finally the recheck calculation and safety evaluation were made over the building structure. The result shows that the foundation digging leads to new cracks on the nearby residential building but does not endanger its structural safety; after the foundation was backfilled, the hidden danger on the building’s northern side slop was eliminated and the structure cracks tend to be stable; the complete engineering structure is safe and in conformity with the requirements of safety and anti-vibration during the construction period, however, the multiple-pore slabs’ piecing affects the structural integrity and vibration proof performance.

Abstract: ZJ200 Portable Steel Bridge has its roots in the Bailey design, but the application of high-grade steels and advanced computer design and finite element analysis (FEA) techniques led to more effective structures. The design of the Bridge is modular, allowing full spans up to 60 meters in 3.048 m increments. Highways Loads up to HS25-44 have been proven during extensive testing.

Abstract: With the study of the 3rd conference hall of Dalian International Conference Center, test and relevant calculation are applied to the structural natural frequency and floor vibration due to human excitations. The Monte Carlo stochastic analysis is applied to the cases in which the comfort for vibration due to crowd excitations may exceed the limit. The results show that the Monte Carlo stochastic method and load curves of excitations are reliable, but in the actual test the high-order harmonic effect of walking excitation is not obvious. In the stochastic analysis with the closer frequency and phase of crowd excitations or the greater population density, the discreteness of results is smaller. Compared with the population density, the differences of frequency and phase of crowd excitations lead to a bigger discreteness of results. With the bigger discreteness of frequency and phase of excitations, the peak accelerations of stochastic model are significantly smaller than the simplified model with the same frequency and phase.

Abstract: Precast concrete screw pile is a new kind of pile foundation. Because the pile bears very large torsion in construction, the torsional properties of pile body including cracking torsion, ultimate torsion and torsional deformation were studied in this paper in order to improve the anti-torsional ability of precast concrete screw pile. Experimental method and numerical method are used to research the torsional behavior of precast concrete pile body. Experimental and numerical results of cracking torsion, ultimate torsion and relationship between torsion and angle of twist per unit length of different specimens are obtained. In addition, five factors of strength level of concrete, degree of prestress, distance of spiral hoop, concrete cover and diameter of spiral hoop influencing on torsional behavior of precast concrete pile body are researched by orthogonal numerical test. The rational finite element model and solution method are concluded for calculating the torsional behavior of concrete pile. Moreover, the rational pile type and design parameters of precast concrete screw pile are obtained.

Abstract: The load of pre-stress structure comes from stretching of steel strand, but the stress built on the steel strand would be lost. The lost causes many problems on the structure, such as pre-stress uneven and margin of safety reduced. Monitoring stress lever on the steel strand can provide information of the structure, and then expert can estimate the behavior under load of structure. It is hardly to monitor the whole-span and whole length of steel strand by traditional senses and method, because of measure range, protection and interference of electromagnetic environment. A novel method based on Optic Fiber Bragg Grating (OFBG), which mentioned in the article, provides a successful experience on the monitoring of pre-stress loss in whole-span and whole length.

Abstract: Based on available theories and practical experience, this paper present an analytical method used for analyzing thermal stresses of over-long concrete slab through design for a real typical structure. Construction sequence, temperature conditions and material properties were considered. It stated that overlong non-joint structures exceeding code limits could be adopted according to the result from the structural analysis.

Abstract: The new composite sandwich slab of the cold formed thin-walled steel and lightweight aggregate concrete is studied. The composite sandwich slab is a skeleton of cold formed thin-walled steel, cast-in-situ lightweight aggregate concrete, built-in benzene board as a sandwich layer. The composite sandwich slab has a light weight, seismic performance is good, and construction period is short of advantage, can effectively solve poor shortcomings of the steel structure fireproofing performance and corrosion resistance, and can effectively improve the whole and local stability of the steel structure. The composite sandwich slab bearing capacity of the cold formed thin-walled steel and lightweight aggregate concrete is analyzed using simple plastic theory. The deflection to consider interface slip of the composite slab is computed. The composite sandwich slab is tested statically; the failure mechanism of the slab is analyzed. The load-deflection curve, load-strain curve are obtained. The sandwich rate of the slab on the influence of the bearing capacity is analyzed using the finite element method, and theoretical with experimental results comparatively analyzed.

Abstract: The health monitoring for long-span bridges has become a hotspot in civil engineering. However, because of the complexity and particularity in bridge structure, monitoring variables are greatly influenced by environmental factors, which results in more difficulties in evaluation. The paper analyzes structural responses in different temperature fields, and the results show that effect of temperature difference among members and temperature gradient are remarkable on structures. The results may be of reference for formulation of bridge health monitoring strategies.

Abstract: Directed toward the feature of restrained torsion of concrete box girder bridge, the layered approach of analyzing restrained torsion is put forward, displacement model and geometric equation are established by using the generalized coordinates principle, and the formula of restrained torsion shear stress is derived, and then a analytical theory of restrained torsion of thick-walled box girder is established based on the mixed variational principle. The numerical experiment indicate that it cannot be neglected that thick-walled effect of restrained torsion of concrete box girder bridge and the predicted results by the new theory are accurate.