共查询到20条相似文献,搜索用时 15 毫秒
1.
结合某实桥工程背景,对节段预制箱梁进行后浇横隔墙施工过程的水化热效应进行了研究,使用有限元软件ANSYS建模,根据三维瞬态温度场理论,进行了水化热效应的仿真模拟,分析了箱体温度场和应力场的分布及随时间变化情况,揭示了水化热温度应力使预制箱体腹板外表面受拉、内侧受压的规律及峰值拉应力区域,指出容易开裂的位置;分析了水泥品种、混合材料用量、入模温度3个参数对应力场的影响规律及影响程度.结果表明:水泥品种对水化热效应的影响最大,其次是混合材料用量的影响,入模温度对水化热效应的影响最小. 相似文献
2.
Peiheng Long Xianting Du Weizhen Chen 《Frontiers of Architecture and Civil Engineering in China》2008,2(3):274-280
The formula for the contribution of prestressed reinforcement on embedded reinforcement element is derived according to the
mechanical behavior of PC bridges and the foundational principle of finite element method. Mechanical concept is definite
and examples validate the calculation results. Reinforcement element model allows generating a finite element mesh without
taking into consideration the layout of reinforcements. Furthermore, the prestressing tendon may pass through the concrete
elements in an arbitrary manner. It is an effective approach that the no-node loads are diverted from the tendons to the adjacent
concrete elements. A useful arithmetic analysis of the spatial curved tendon PC Bridges is provided.
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Translated from Journal of Tongji University (Natural Science), 2007, 35(4): 455–460 [译自: 同济大学学报(自然科学版)] 相似文献
3.
箱梁零号块水化热分析 总被引:1,自引:0,他引:1
箱梁零号块由于混凝土体积较大,施工过程中,水泥水化反应放热,导致混凝土在硬化期间承受了较大的温度应力,采用瞬态热应力有限元分析方法,对箱梁零号块进行了温度场和应力场分析。分析了箱梁零号块在浇筑后不同时间段的温度场和应力场。总结了箱梁零号块水化热反应期间梁体受力不利部位。同时为了降低混凝土水化热,对不同水泥含量的混凝土进行了水化热分析,分析结果表明:低放热水泥能有效降低箱梁零号块的温度应力,大大降低混凝土开裂风险。 相似文献
4.
5.
Ying WANG Zhaoxia LI Baijian WU 《Frontiers of Architecture and Civil Engineering in China》2008,2(3):197-204
The monitoring of fatigue stress of steel bridge is a key issue of bridge health monitoring and safety assessment. This paper
aims to find out the strain history features of the girder components of Runyang Suspension Bridge (RYSB) under vehicle and
environmental loading during its first year of service based on the strain-history data recorded by structural health monitoring
system installed in the bridge. The fatigue stress spectrums of steel box girders under normal traffic load, heavy trucks
and typhoon loads were studied as well as the correlation between varying strain and temperature based on real-time monitoring
of temperature histories. The results show that, monitoring on local strain in health monitoring systems of RYSB can effectively
provide the information on fatigue stresses. The range of the equivalent fatigue stress on the monitoring location of the
bridge is currently low, mainly due to varying traffic loading and temperature. There exists significant correlation between
varying temperature and mean value of fatigue stress. Effect of the passing of heavy trucks on bridge fatigue is quite significant
since the value of the cumulative fatigue damage generated by heavy trucks is 10 to 100 times larger than that by normal traffic.
Therefore, the effect on fatigue cumulative damage due to heavy trucks or overloaded vehicles needs to be monitored and paid
much attention to.
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Translated from Journal of Southeast University (Natural Science Edition), 2007, 37(2): 280–286 [译自: 东南大学学报(自然科学版)] 相似文献
6.
大体积混凝土温度场构成因素分析 总被引:1,自引:1,他引:0
大体积混凝土的水化热不容易及时散发,内部温升将会很高,从而产生很大的温度应力,导致出现温度裂缝。本文介绍了环境温度、水泥水化热、截面尺寸等对温度场的影响,分析了大体积混凝土温度场的变化规律,提出了大体积混凝土施工方法的一些建议,为实际工程的应用提供了选择依据,可为同类工程施工提供参考。 相似文献
7.
Haitao Sun Yuanhan Wang Yu Miao 《Frontiers of Architecture and Civil Engineering in China》2008,2(2):166-171
A normalized space constructed by tensor product is used in field function approach to give a special case of moving least
squares (MLS) interpolation scheme. In the regular domain, the field function which meets homogenous boundary conditions is
constructed by spanning base space to make the MLS interpolation scheme simpler and more efficient. Owing to expanded basis
functions selection, some drawbacks in general MLS method, for example repeated inversion, low calculation efficiency, and
complex criterions, can be avoided completely. Numerical examples illustrate that the proposed method is characterized by
simple mathematical concept, convenient repeat calculations with high accuracy, good continuity, less computation and rapid
convergence.
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Translated from Journal of Huazhong University of Science and Technology (Nature Science), 2007, 35(2): 8–11 [译自: 华中科技大学学 报(自然科学版)] 相似文献
8.
Min Li Hongtao Kao Chunxiang Qian 《Frontiers of Architecture and Civil Engineering in China》2008,2(3):281-287
To evaluate the remaining durability of concrete materials after combustion, the permeability of high strength concrete (HSC)
after combustion was studied. The transport behavior of chloride ion, water and air in concrete after combustion and the effect
of temperature, strength grade, and aggregation on the permeability of HSC after combustion are investigated by chloride ion
permeability coefficient (D
c), water permeability coefficient (D
w) and air permeability coefficient (D
a). The experiment results show that all three permeability coefficients commendably reflect changes of permeability. The permeability
coefficient increases with the evaluation temperature. After the same temperature, the permeability coefficient of HSC is
lower than that of normal strength concrete (NSC). However, the degree of degradation of permeability coefficient of HSC is
greater than that of NSC. The permeability resistance of HSC containing limestone is better than that of HSC containing basalt.
Combining changes of compressive strength and permeability, the remaining durability of concrete materials after combustion
is appropriately evaluated.
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Translated from Journal of Southeast University (Natural Science Edition), 2006, 36(5): 825–830 [译自: 东南大学学报(自然科学版)] 相似文献
9.
Chujie Jiao Wei Sun Shi Huan Guoping Jiang 《Frontiers of Architecture and Civil Engineering in China》2009,3(2):131-136
Impact compression experiments for the steel fiber-reinforced high-strength concrete (SFRHSC) at medium strain rate were conducted
using the split Hopkinson press bar (SHPB) testing method. The volume fractions of steel fibers of SFRHSC were between 0 and
3%. The experimental results showed that, when the strain rate increased from threshold value to 90 s−1, the maximum stress of SFRHSC increased about 30%, the elastic modulus of SFRHSC increased about 50%, and the increase in
the peak strain of SFRHSC was 2–3 times of that in the matrix specimen. The strength and toughness of the matrix were improved
remarkably because of the superposition effect of the aggregate high-strength matrix and steel fiber high-strength matrix.
As a result, under impact loading, cracks developed in the SFRHSC specimen, but the overall shape of the specimen remained
virtually unchanged. However, under similar impact loading, the matrix specimens were almost broken into small pieces.
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Translated from Journal of Southeast University (Natural Science Edition), 2007, 37(5): 892–897 [译自: 东南大学学报(自然科学版)] 相似文献
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Wang Yiqun Xu Yidong Zhao Yanjing Chen Yunxia 《Frontiers of Architecture and Civil Engineering in China》2007,1(2):176-181
Thousands of columns with special shape are analyzed by nonlinear numerical methods. The ductility is calculated to investigate
the limit of the axial force ratio and circumstantial requirement for stirrups of an reinforced concrete (RC) column with
special shape, in the point of view of the characteristic value for providing stirrup. The limit of the axial force ratio
of columns with special shape in relation to the characteristic value of the stirrup is obtained. Then, the effect of stirrup
arrangement on the ductility of the RC column is discussed in case of buckling of the longitudinal reinforcement and constraint
concrete columns. The complete requirement for stirrups of RC column with special shape is given.
Translated from Journal of Tianjin University (Natural Science Edition), 2006, 39(3): 295–300 [译自: 天津大学学报 (自然科学版)] 相似文献
12.
在混凝土箱梁模型上布设479个温度测点,对箱梁在水化热期间的温度变化规律进行精密测量。通过德洛内三角网格算法,建立用于混凝土箱梁温度测量的温度传感器点阵,绘制箱梁全截面在水化热期间的温度场云图,进而分析混凝土箱梁的水化热温度发展规律。研究结果表明:箱梁的水化热温度场基本呈对称分布,其中腹板水化热温度变化最大,最高温度为64.8℃,顶板、底板与腹板的最大平均温升比值约为1∶1.1∶1.4;底板水化热温度最先达到峰值,为混凝土浇筑后11h;腹板的平均温度峰值出现在浇筑后12h;顶板温度峰值相对滞后,为混凝土浇筑后13h;箱梁各板沿厚度方向的水化热温度服从高斯分布形式;顶板、底板沿宽度方向水化热温度呈双峰对称分布,服从二项组合式的高斯分布模型,而腹板的水化热温度沿板高可认为常量。此外,文中给出了箱梁模型关键位置在水化热期间的温度数据,可用于指导混凝土箱梁水化热温度试验的测点布置,并且为箱梁的水化热温度控制和设计提供参考。 相似文献
13.
Chen Changfu Xiao Shujun Yang Yu 《Frontiers of Architecture and Civil Engineering in China》2007,1(3):329-333
Based on the unified strength theory [1], a unified strength criterion for strain softening materials, such as concrete or
rock, was derived, and the elastic and plastic limit loads of a thick-walled cylinder made of these materials subject to external
pressure were also given. In addition, the influence of some factors on the limit loads of such cylinders as the ratio of
the external radius to internal radius, r
b/r
a, the coefficient b, which reflects the effect of medium principal stress and the normal stress of the relevant surface on the material destroy
degree, the ratio of tensile strength to compressed strength of the material, α, and the damage variable β were discussed
in detail. Some examples were given and some meaningful results were obtained.
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Translated from Journal of Hunan University (Natural Science), 2006, 33(2): 1–5 [译自: 湖南大学学报 (自然科学版)] 相似文献
14.
Chunlin Ding Xiaohong Meng 《Frontiers of Architecture and Civil Engineering in China》2009,3(3):299-304
The similarity law of centrifuge test was developed for the seepage field and stress field of a foundation pit with confined
water by analyzing control equations, and a similarity index and a similarity coefficient of centrifuge test were obtained.
Based on the deep foundation pit of the Huangxing Road Station of the Shanghai metro line M8, the deformation stability of
the pit was tested. Finally, a comparative study was conducted on the test results of the pit deformation and the field measurement
results. Comparison results show that the pit deformation regularity of the test is basically identical with that of the field
measurement, and the difference in pit deformation between the test and the field measurement is within 50%. The centrifuge
model test can effectively simulate the displacement response of the ground and retaining structure during dewatering and
excavation for the pit with confined water, which provides a reliable basis for the design and construction of the pit with
confined water.
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Translated from Journal of Tongji University (Natural Science), 2008, 36(1): 23–26 [译自: 同济大学学报(自然科学版)] 相似文献
15.
Yuedong SUN Jianzhuang XIAO Research 《Frontiers of Architecture and Civil Engineering in China》2008,2(4):302-308
A study is conducted on the seismic behavior of one natural concrete frame and two recycled concrete frames with 100% recycled
coarse aggregate whose scales are 1:2 entirely, and a comparative study is conducted under low-reversed cyclic lateral loading
and different vertical loading. This work aims to estimate the failure mechanism, hysteresis loops, displacement ductility,
deterioration of strength and stiffness and energy dissipation of recycled concrete frames under low-reversed cyclic loading
as well as the influence of different vertical loading. Analysis on the basis of the experiment proves that it is entirely
feasible to apply recycled concrete to practical engineering for the sake of its good seismic behaviors. Theoretical base
is provided for further study and practical application of recycled concrete structure.
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Translated from Journal of Tongji University (Natural Science), 2007, 35(8): 1013–1018 [译自: 同济大学学报(自然科学版)] 相似文献
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17.
温度场对箱梁的温度应力和挠度有很大影响,温度应力是混凝土箱梁产生裂缝的主要原因之一。通过对某在建大跨度混凝土连续箱梁桥内部温度场的现场测试,拟合了温度场沿箱梁高度方向的分布函数。运用有限元软件ANSYS分别计算了该桥按铁路桥规、公路桥规和实测温度场施加温度荷载作用下的挠度和应力,通过结果对比,对该桥的温度效应进行了总体... 相似文献
18.
Yong Ding Baizhan Li Qing Luo Hong Liu Meng Liu 《Frontiers of Architecture and Civil Engineering in China》2009,3(2):211-218
This paper analyzes the potential of natural resources to improve the indoor thermal environment in Chongqing through the
statistical analysis of natural resources including solar energy, wind, water, and earth, etc. The building form, systems,
and principle of usage of natural resources are briefly analyzed through the building site decision, building form design,
and computer simulation, which will be the real reference for the design of building energy efficiency.
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Translated from Journal of Chongqing University (Natural Science Edition), 2007, 30(9): 127–133 [译自: 重庆大学学报(自然科学版)] 相似文献
19.
Jinyang Jiang Wei Sun Yunsheng Zhang Cuicui Chen Jing Wang 《Frontiers of Architecture and Civil Engineering in China》2008,2(2):179-183
The mix ratio of steel fiber reinforced concrete (SFRC) was optimized using the principles that workability must meet the
pumping demand and anti-cracking performance should be optimal. The effect of SFRC on the initial cracking load, the ultimate
load and the crack width of the reinforced concrete (RC) member were analyzed in this paper. It was found that the admixture
had good preservation of moisture and adhesion and the fibers distributed homogeneously in one hour out of the machine. According
to the pumping results, the SFRC could be pumped vertically up to 306 m. Based on the standard computation formula of cracks,
the maximum crack width of an RC member with 0.8% steel fiber (by volume) is about 32% lower than that of standard RC member.
Through an experimental research on full-scale model tests for the steel and concrete composite anchorage zone on a pylon,
the SFRC not only remarkably increases the crack resistance and the ultimate load, but the initial load also improves 33%a
pproximately. It is also indicated that plastic shrinkage cracking of SFRC in which volume fraction of steel fibers is 0.8%
can be restrained obviously and the unrestrained drying shrinkage can be diminished by about 50% at early age. The results
confirmed that the SFRC can lessen the shrinkage crack of concrete and enhance markedly the direct tensile strength. Therefore,
the SFRC can solve the key question of crack resistance for the anchorage zone of a bridge tower.
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Translated from Journal of Southeast University (Natural Science Edition), 2007, 37(1): 123–127 [译自: 东南大学学报(自然科学版)] 相似文献
20.
波形钢腹板组合箱梁作为一种新型组合结构,由于其结构的特殊性,在日照温差作用下产生的桥面板横向应力需要进行深入研究与分析。论文基本平面外抗弯刚度相等的原则对波形钢腹板组合箱梁的横向框架计算提出了简化计算模型。依据现有的设计规范,计算了箱梁顶板在温度梯度作用下的温度自应力及次应力,并与同类型的混凝土箱梁进行比较,计算结果表明,波形钢腹板组合箱梁对温度梯度的敏感性较低,对于防止箱梁顶板出现纵向裂缝有一定优势。论文的结论可为波形钢腹板组合箱梁横向设计提供参考。 相似文献