Applied Mechanics and Materials Vols. 166-169

Abstract: Relative responses can strongly determine damages of bridge structures, e.g. due to pounding and unseating of girders as observed in many major earthquakes in the past. In the investigations often uniform ground excitation and pounding at only one location are considered. Studies on the influence of spatially varying ground excitation on bridge responses are still very limited, and they are restricted to flat ground-surface condition. Influence of multi-sided pounding is also not much investigated. If the impediment effect of abutments is considered at all, so far fixed-base movements are assumed. The consequence of non-uniform movement and pier-support movements for the force development in bridge structures is not investigated yet. It is the subject of our current study.

Abstract: After the earthquake, the extent of the destruction of the structure will directly influence the ability to resist the after-shock and the carryout of rehabilitation, the study on the damaged structures’ seismic performance is very important and complex. The seismic evaluation and strengthening of RC damaged structures must not only ensure the safety of structures, but also have enough ability to resist the earthquake in the last life-span. While a performance-based criterion, both for the design of new construction and the retrofit of existing construction, is very desirable, the process of developing such a guideline can be formidable. In this paper, basic idea and design process of performance-based design is discussed firstly. Then story drift ratio and deformation of component are used as performance targets to solve the problems of seismic evaluation and strengthening for damaged reinforced concrete structures under different performance levels ， the specific performance-based design method is listed to provide theoretical basis of strengthening of damaged structures.

Abstract: In order to improve the seismic behavior of the rural masonry buildings and reduce the cost and be convenient for construction, a precast tie-column system was put forward, which was suitable for masonry buildings, constructed by fired common bricks or porous bricks. The uniaxial compression constitutive relation of brick masonry was used for simulating the precast tie-column. And this paper analyzed the difference of the seismic behavior of masonry walls which bearing different vertical compressive stress, and confined by cast-in-place tie-columns or precast tie-columns, and whether contain windows or not. The results show that the uniaxial compression constitutive relation used for simulating precast tie-column is reasonable and the seismic behavior of masonry walls confined by precast tie-columns is better than the wall without tie-colums, and equal to those confined by cast-in-place tie-columns.

Abstract: This paper examines the A1 tower of the Shenyang Huafu Xintiandi Phase III project as an example of an out of code structure. It also analyzes the seismic performance under three earthquake scenarios; a frequent earthquake, a moderate earthquake and a rare earthquake. This paper will discuss the structural elements design, and address the weak points. This paper also provides several seismic design enhancements for similar high-rise buildings.

Abstract: Since recent advances of technology in material science and increasing demand for high strength steel, Q460 high strength steel has been applied to several landmark buildings and major projects. However, the application of high strength steel in seismic structures is limited by the relative worse ductility, which is usually decreasing with the increasing on yield strength. For this purpose, key issues of using high strength steels in seismic structures are discussed and two design methodologies are proposed. Recent research progress on application of high strength constructional steel achieved at Tongji University is introduced. Finally, future work related to the application of high strength steels are recommended.

Abstract: Based on 266 strong ground motions from 15 significant earthquakes in California of America, the attenuation law of hysteretic spectra is established by using nonlinear regression method, and the effects of site class and ductility level on the hysteretic spectra constructed from the attenuation relationship are discussed in the paper. The results show that the site has significant effects on hysteretic energy spectra, and the more soft the site is, the more hysteretic energy structure will suffer from earthquake. Moreover, for ductility level scaled by ductility factor, the results show that structure with greater ductility factor can dissipate more input energy from the earthquake by means of the plastic deformation. The up limit design value of ductility factor for a structure is proposed as 4 because there is little difference between the hysteretic energy demand for ductility factor 4 and larger values. The hysteretic energy demand for structures at a given site in scenario earthquakes can be evaluated according to the results of the paper.

Abstract: This paper describes the study about multilayer and high-rise precast prestressing shearwall structure ,we made one shape,T shape and linked limb shearwall specimens as the objects,we also made comprision with cast-in-place shearwall,the specimens were tested under high frequency and reciprocating horizontal load.Based on the test,we used the finite element software ANSYS to do a nonlinear elasto-plastic analysis about the whole process under different compression ratios and different effective prestress to research seismic performance, failure mode and elasto-plastic analysis.The results show that the edge members are the maximum force position and the most important energy dissipation part of the shearwall limb.

Abstract: Based on the mechanics characteristics of the viscoelastic dampers, the seismic performance of a 5 layers steel frame structure with viscoelastic dampers or not was researched. In under the action of the rarely met earthquake, the finite element analysis software MIDAS was used to analyses two of the models of displacements, interlayer shear and ductility of structure. The results showed that: after the installation of viscoelastic dampers, the displacements and interlayer shear of the structure reduced significantly, and ductility increases, the earthquake response can be cut down obviously, it shows better seismic performance.

Abstract: Rubber bearing base-isolation is well-developed vibration reduction technique and is applied in practical engineering broadly. The nature period of the base-isolation structure applied with rubber bearing is extended. Meanwhile the response of the superstructure is also reduced. But it is noticed that the displacement of isolation layer is too large. So it is required to find a suitable damper to reduce the displacement of isolation layer. Magnetorheological damper has good smart performances- broad controlled band, fast response and demand a little energy. In this paper smart base isolation system, which is combined with rubber bearing and MR damper is applied to structural vibration control, and have numerical simulation e of structure employing RB isolation and smart isolation in different kind and magnitude of earthquake waves. The result indicates the control system is effective.

Abstract: Regarding the distribution modes of longitudinal horizontal seismic forces of single-story factory building with no purlin concrete roof, there are conflicts between Sections 9.8.1 and 5.2.6 in the Seismic Design of Buildings GB50011-2010[1]. We suggested distributing the longitudinal seismic forces according to the proportion of the gravity loads on the subordinate areas of the lateral force components. We recommended replacing clause 1 of section 9.1.8 with “Don’t consider the effective stiffness of the enclosure walls or the partition walls”. Then for the example in Single-story Factory building Design Examples, we calculated the longitudinal seismic forces with two methods, and proved the our recommended method was correct.