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Analysis on dynamic response of reinforced reactive powder concrete two-way slabs under blast load

Jianzhu Jiegou Xuebao/Journal of Building structures 2014年 35卷 91-98页

作者： Hou, Xiaomeng Li, Gang Zheng, Wenzhong Key Lab of Structures Dynamic Behavior and Control of China Ministry of Education Harbin Institute of Technology Harbin150090 China

Reactive powder concrete (RPC) is a kind of new cementitious composite material with super high performance and high toughness, which has extensive application prospect in protective engineering. The dynamic response of RPC slabs is the basis of design of structures to resist blast. Based on compressive and tensile split Hopkinson pressure bar test results, empirical relations of dynamic increase factor (DIF)-strain rate for RPC were obtained. An approach for modeling reinforced RPC slabs under blast is presented using the software LS-DYNA. The validity of the model was established by comparing predictions from numerical analysis with relating test results. Results from parametric studies indicate that dynamic displacement of slabs is reduced significantly by considering the strain rate effect. The dynamic displacement of slabs is decreased by increasing scaled distance of blast load, depth of slabs, compressing strength of PRC and reinforcement ratio of slabs. Boundary conditions and depth of slabs have significant influence on dynamic response of RPC slabs, while load level and reinforcement ratio have minor influence on dynamic response of RPC slabs. It is an effective method to increase the depth of slabs and restraint effects to improve the blast-resistant of slabs. ©, 2014, Science Press. All right reserved.

关键词： dynamic response

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Effects of temperature on drying shrinkage of concrete

Effects of temperature on drying shrinkage of concrete

引用

4th International Conference on Civil Engineering, Architecture and Building Materials, CEABM 2014

作者： Yang, Ying Zi Li, Mao Guang Deng, Hong Wei Liu, Qi Key Lab of Structures Dynamic Behavior and Control Harbin Institute of Technology Ministry of Education Heilongjiang Harbin 150090 China School of Civil Engineering Harbin Institute of Technology Harbin 150090 China

ISBN: (纸本)9783038351665

The present study investigated experimentally effects of temperature on drying shrinkage of concrete in different water cement ratio and containing mineral admixture. Concrete was exposed to a controlled environment of 20±1°C, 35±1°C, 50±1°C, and 60% ± 5 RH, respectively. The drying shrinkage of concretes with water cement ratio of 0.3, 0.4 and 0.5 were evaluated. The resuluts showed that with the increase of temperature from 20 °C to 50 °C, the influence of water cement ratio on drying shrinkage of concrete was gradually weakened. The shrinkage strain of concretes with replacement of cement by 20% of ground granulated blast- furnace slag (GGBS), 10% of silica fume (SF), and 20% of fly ash (FA)were measured, respectively. Test results showed that GGBS had a little impact on drying shrinkage of concrete;Silica fume could increase the drying shrinkage of concrete significantly in the early and later ages, especially when concrete was subjected to high temperature;Fly ash reduced drying shrinkage in early ages and increased drying shrinkage of concrete in the later ages. © (2014) Trans Tech Publications, Switzerland.

关键词： Cements

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Research on influence of thermosiphon layout on cooling effect on transmission line pile foundation in permafrost region

Research on influence of thermosiphon layout on cooling effe...

引用

2014 International Conference on Sensors Instrument and Information Technology, ICSIIT 2014

作者： Yu, Hao Lin Xu, Xue Yan Wang, Wei Li, Ming Xuan Key Lab of Structures Dynamic Behavior and Control Harbin Institute of Technology Ministry of Education Heilongjiang Harbin 150090 China School of Civil Engineering Harbin Institute of Technology Harbin 150090 China

ISBN: (纸本)9783038350392

Research work on the thermosiphon layout design of transmission line pile foundation in Geermu permafrost region was performed by finite element method and the influence of thermosiphon layout design on the temperature of soil around pile foundation was calculated and analyzed. The numerical calculation results indicated that the cooling effect of thermosiphon was obvious, but the coolling effect varied with the difference of thermosiphon layout design. The more thermosiphon bars were laid out aound pile foundation, the lower the temperature of soil around pile foundation. The cooling effect of thermosiphon on pile foundation and soil became weaker and weaker with the increment of the horizontal distance between soil and thermosiphon-pile. The layout design of 12 thermosiphon bars was the best for the transmission line pile foundation in permafrost region. © (2014) Trans Tech Publications, Switzerland.

关键词： Piles

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Node shift method for stiffness-based optimization of single-layer reticulated shells

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2014年第2期15卷 97-107页

作者： Chang-yu CUI Bao-shi JIANG You-bao WANG School of Civil Engineering Harbin Institute of Technology Harbin 150090 China Key Lab of Structures Dynamic Behavior and Control (Harbin Institute of Technology) Ministry of Education Harbin 150090 China

This paper presents a node shift method to find the optimal distribution of nodes in single-layer reticulated shells. The optimization process searches for the minimum strain energy configuration and this leads to reduced sensitivity in initial imper- fections. Strain energy sensitivity numbers are derived for free shift and restricted shift where nodes can move freely in the 3D space or have to move within a predefmed surface respectively. Numerical examples demonstrate the efficiency of the proposed approach. It was found that optimized structures achieve higher ultimate load and are less sensitive to imperfections than the initial structure. The configuration of the final structure is closely related to factors like the initial structural configuration, spatial conditions, etc. Based on different initial conditions, architects can be provided with diverse reasonable structures. Furthermore, by amending the defined shapes and nodal distributions, it is possible to improve the mechanical behavior of the structures.

关键词： Node shifts Strain energy sensitivity Structural optimization Static stability Imperfection sensitivity

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Parametric modeling and stability analysis of temporary grandstand

Parametric modeling and stability analysis of temporary gran...

引用

4th International Conference on Civil Engineering, Architecture and Building Materials, CEABM 2014

作者： He, Lin Liu, Cong Wu, Zhen Yu Key Lab of Structures Dynamic Behavior and Control Harbin Institute of Technology Ministry of Education Heilongjiang Harbin 150090 China School of Civil Engineering Harbin Institute of Technology Heilongjiang Harbin 150090 China

ISBN: (纸本)9783038351641

Temporary grandstands bear crowd load, which is created when spectators jumping on the structure. The simplified loads applied to temporary grandstand have been obtained based on experiment data of human body jumping forces. By the ABAQUS software, the parametric and automatic modeling of three-dimensional (3D) temporary grandstand structures has been realized with Python scripting. The linear buckling analysis and nonlinear buckling analysis of the structure have been carried out. The ultimate bearing capacity and the structural deformation under crowd load have been acquired. Results show that the nonlinear effect of the structure under crowd load is very obvious;the linear buckling analysis cannot get the ultimate bearing capacity of the structure and the first order buckling mode cannot simulate the final deformation of the structure either. The research of this paper greatly improve the efficiency of the construction and automation design of temporary structures and reveal the mechanical behavior of such structure to a certain degree. © (2014) Trans Tech Publications, Switzerland.

关键词： Python

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FEA on mechanical behavior of axially restrained concrete-filled steel tubular columns subjected to fire

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Jianzhu Jiegou Xuebao/Journal of Building structures 2015年 36卷 310-317页

作者： Liu, Faqi Pan, Yanchong Yang, Hua Key Lab of Structures Dynamic Behavior and Control of China Ministry of Education Harbin Institute of Technology Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China Tianjin Fire Research Institute of the Ministry of Public Security Tianjin300381 China

The internal force and the deformation of the column exposed to fire in structure change due to the restraint provided by adjacent members, which may affect the fire resistance. However, most of previous studies focused on the fire performance of individual concrete-filled steel tubular (CFST) column, without considering the structural interactions between the column and its adjacent members. A finite element model of axially restrained circular CFST column was developed with ABAQUS to analyze the influence of axial restraint on the axial force, axial displacement and fire resistance. It is found that axial restraint has significant influence on the axial force, which intensifies the axial force during the expansion period and relieves the axial force during the contraction period. The axial displacement decreases correspondingly, which enhances the fire resistance. The influences of parameters on the fire resistance of axially restrained columns were studied, including cross-sectional dimension, load ratio, slenderness ratio and load eccentricity ratio. The results show that the fire resistance can be increased by 10% to 40% for columns with the axial restraint stiffness ratio of 0.02 and slenderness ratio less than 30, and the beneficial effect on the fire resistance can be considered. The higher fire resistance can be attained with larger cross-sectional dimension, smaller load ratio and smaller slenderness ratio for both axially restrained and unrestrained columns. Different from members without axial restraint, the load eccentricity ratio has noticeable influence on the fire resistance of restrained columns. ©, 2015, Science Press. All right reserved.

关键词： Finite element method

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Fragility-based probabilistic seismic safety assessment of RC frame structures with infilled masonry walls

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Tumu Gongcheng Xuebao/china Civil Engineering Journal 2014年 47卷 260-265页

作者： Yu, Xiaohui Li, Yanjun Lu, Dagang Jia, Mingming Fan, Feng Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China Jinan University Jinan250022 China

A suit of real ground motion records are selected as inputs. The empirical thresholds provided by the Chinese seismic design code are adopted as the definitions of the concerned limit states. Then the seismic fragility analysis is conducted for the three-story, five-story and ten-story RC frames with and without infilled masonry walls. The limit state failure probabilities and the damage state failure probabilities conditioned on the frequent earthquake, the design-based earthquake and the major earthquake are calculated. As compared to the results from the RC bare frames we can find that the infilled masonry walls can effectively reduce the failure probability of the RC frame structures under various earthquakes and can consequently promote the safety levels against earthquake.

关键词： Earthquakes

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Hysteretic phase transition sequence in 0.67Pb(Mg1/3Nb2/3)O3−0.33PbTiO3 single crystal driven by electric field and temperature

引用

Physical Review B 2015年第18期91卷 184105-184105页

作者： Limei Zheng Xiaoyan Lu Hengshan Shang Zengzhe Xi Ruixue Wang Junjun Wang Peng Zheng Wenwu Cao Condensed Matter Science and Technology Institute Harbin Institute of Technology Harbin 150080 China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education School of Civil Engineering Harbin Institute of Technology Harbin 150001 China Shaanxi Key Laboratory of Photoelectric Functional Materials and Devices School of Materials and Chemical Engineering Xi'an Technological University Xi'an 710032 China College of Electronics and Information Hangzhou Dianzi University Hangzhou 310018 China Department of Mathematics and Materials Research Institute Pennsylvania State University University Park Pennsylvania 16802 USA

Domain pattern variations with temperature were studied by polarizing light microscopy for the morphotropic phase boundary composition 0.67Pb(Mg1/3Nb2/3)O3−0.33PbTiO3 (PMN-0.33PT) single crystal. At room temperature, the monoclinic MA phase is the dominant phase in the unpoled crystal, which coexists with a small fraction of the tetragonal (T) phase. The orientation of spontaneous polarization was calculated to be ∼4.8∘ away from the pseudocubic 〈111〉C in the {001}C plane family. Under an electric field of 6 kV/cm along [011]C, a single domain orthorhombic (O) phase was induced but partially switched back to MA a few hours after the removal of the E field. It was found that the temperature induced phase transition sequence of the [011]C poled PMN-0.33PT single crystal is strongly hysteretic. On heating, the phase transition sequence is as follows: coexistence of O phase and MA→rhombohedral→monoclinicMC→cubic(C). On cooling, the phase transition sequence is given by C→T→MA. The complete set of dielectric, piezoelectric, and elastic constants for the [011]C poled PMN-0.33PT single crystal was measured, which showed the strong feature of the single domain O phase with high shear (d15=2321pC/N,d24=1941pC/N) and low longitudinal piezoelectric coefficients (d33=165pC/N).

关键词： SINGLE crystals ELECTRIC fields TEMPERATURE POLARIZATION (Electricity) PIEZOELECTRIC devices

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Strategic positioning of FRP anchors in frpstrengthened slabs 7

Strategic positioning of FRP anchors in frpstrengthened slab...

引用

7th International Conference on FRP Composites in Civil Engineering, CICE 2014

作者： Zhang, Huawen Smith, Scott T. Wang, Zhenyu Southern Cross University Australia Department of Engineering Southern Cross University Australia Key Lab of Structures Dynamic Behavior and Control Ministry of Education China School of Civil Engineering Harbin Institute of Technology Heilongjiang Harbin150090 China

ISBN: (纸本)9781771363082

A common problem associated with the strengthening of reinforced concrete (RC) structures with externally bonded fibre-reinforced polymer (FRP) composites is the ability of the FRP to prematurely debond. The installation of anchorage devices is an intuitive and logical means with which to enhance the debonding resistance of such strengthening systems, however, there are limited comprehensive experimental studies to date. Anchors may also enhance the ductility of the strengthened member although experimental studies are particularly limited that investigate this phenomenon. This paper reports the results of seven reinforced concrete (RC) slab tests of which six slabs were strengthened in flexure with FRP plates. Five of the strengthened slabs were anchored with FRP anchors of different positioning and geometry. Depending on their position of installation, anchors are shown to enhance either the strength alone or both the strength and ductility of the FRP-strengthened slabs.

关键词： Anchors

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Influence of FPB on seismic performance of single-layer reticulated domes under vertical earthquakes

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Tumu Gongcheng Xuebao/china Civil Engineering Journal 2014年 47卷 181-185页

作者： Kong, Dewen Fan, Feng Zhi, Xudong Sun, Menghan Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China Harbin Institute of Technology Harbin150090 China

As an effective base isolation device, friction pendulum bearings (FPB) were finely modeled and applied in the K8 single-layer reticulated domes in this paper. First, influence of friction pendulum bearings was analyzed on the seismic performance of single-layer spherical reticulated shell from two aspects, the peak acceleration and earthquake energy. Moreover, the seismic performance of structure with FPB was studied under different ground motion intensities from three aspects, the dynamic stress, the nodal acceleration, and the vertical relative displacement of nodes. The result showed that the peak vertical acceleration was reduced and a part of earthquake energy was isolated by using FPBs. Under the different ground motion intensities, the seismic effect of a K8 single-layer spherical reticulated shell structure with FPB was similar.

关键词： Earthquakes

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