混凝土梁试验的挠度测量误差分析

对混凝土梁试验的误差进行研究,用不确定度分析、表示挠度测量误差。本试验取16根混凝土梁为研究对象,分别对它的标距测量、百分表示值误差不确定度进行评定。通过设计评定实验建立数学模型,分析不确定度来源,运用统计方法和非统计方法估算概率分布,分别对各不确定度分量进行A类和B类评定,最后根据不确定度传播率合成,给出不确定度分析结果。

混凝土梁试验的挠度测量误差

本文对混凝土梁试验的误差进行研究,用不确定度分析、表示挠度测量误差。主要研究测量不确定度在混凝土梁试验中的应用,分别对标距测量、百分表示值误差不确定度进行评定。通过设计评定实验,建立数学模型,分析不确定度来源,运用统计方法和非统计方法,估算概率分布,分别对各不确定度分量进行A类和B类评定,最后根据不确定度传播率合成,给出不确定度分析结果。

粘贴碳纤维板混凝土和粘贴钢板混凝土的试验研究

根据碳纤维板和钢板粘贴混凝土后进行小梁的抗弯能力试验,观测了梁体在试验荷载作用下的挠度、应力及承载能力,并介绍了佳木斯松花江公路大桥维修加固在材料选用上进行的粘贴碳纤维板和钢板的对比试验的方法、content内容及工艺流程。

复杂系统在桥梁挠度变化异常检测中的应用探究

在复杂系统模式中,桥梁挠度变化异常检测的根本目的是预测复杂系统的涌现形态。相较于传统桥梁挠度变化过程,本文在复杂性科学的基础上,将钢桁-混凝土组合结构试验梁挠度变化认为是满足非平稳时间序列,基于结构向量的异常检测,运用CSSR(因果态分割重构)算法,为桥梁挠度变化异常检测提供一种新的检测理念。

Fatigue behavior of crane beam strengthened with CFRP

In order to study the fatigue behavior of the damaged reinforced concrete （RC） beams strengthened by carbon fiber reinforced polymer （CFRP） laminate, three T-shaped beams strengthened by CFRP and one contrasting beam are tested under fatigue loading, with the parameters of different modes of strengthening and different fatigue load levels considered. The main results obtained from the tests are： the width of the crack decreases 50. 2% to 66%, and the development of the crack is limited; the stress of steel decreases 24. 1% to 28. 2%, and the stiffness increases 14.9% to 16. 1% after being strengthened. Based on the technical specification for strengthening concrete structures with CFRP and the conclusions from the tests, a calculating scheme of the flexure stiffness is given, which can be used for reference in engineering design. Finally, some suggestions are given for design in fatigue strengthening.

Finite element failure analysis of continuous prestressed concrete box girders

In order to analyze the load carrying capacity of prestressed concrete box girders, failure behaviors of in-situ deteriorated continuous prestressed concrete box girders under loading are experimentally observed and a finite failure analysis method for predicting behaviors of box girders is developed. A degenerated solid shell element is used to simulate box girders and material nonlinearity is considered. Since pre-stressed concrete box girders usually have a large number of curve prestressed tendons, a type of combined element is presented to simulate the prestressed tendons of box girders, and then the number of elements can be significantly reduced. The analytical results are compared with full-scale failure test results. The comparison shows that the presented method can be effectively applied to the failure analysis of in-situ continuous prestressed concrete box girders, and it also shows that the studied old bridge still has enough load carrying capacity.

Experimental study and calculation of flexural capacity of RC beams strengthened with GFRP sheets

Nine reinforced concrete (RC) beams strengthened by glass fiber reinforced polymer (GFRP) sheets and three control beams are tested. Four parameters are considered in this experimental program included the concrete strength, the reinforcement ratio, the number of GFRP sheets, and the shear span ratio. It is shown that the application of GFRP sheets can increase the ultimate flexural capacity. The effect of the concrete strength, the reinforcement ratio and the number of GFRP sheets on load capacity is obvious. The shear span ratio can affect the failure mode of RC beams strengthened by GFRP sheets. A theoretical model for flexural behavior of the strengthened RC beam is also developed.

Experimental study and analysis on fatigue stiffness of RC beams strengthened with CFRP and steel plate

The objective of this work is to investigate the fatigue behavior of reinforced concrete(RC) beams strengthened with externally bonded carbon fiber reinforced polymer(CFRP) and steel plate. An experimental investigation and theoretical analysis were made on the law of deflection development and stiffness degradation, as well as the influence of fatigue load ranges. Test results indicate that the law of three-stage change under fatigue loading is followed by both midspan deflection and permanent deflection, which also have positive correlation with fatigue load amplitude. Fatigue stiffness of composite strengthened beams degrades gradually with the increasing of number of cycles. Based on the experimental results, a theoretical model by effective moment of inertia method is developed for calculating the sectional stiffness of such composite strengthened beams under fatigue loading, and the calculated results are in good agreement with the experimental results.

Durability of Stress Ribbon Bridge Checked during Loading Test

Stress ribbon bridges have many advantages and became recently more popular mostly because of their versatile form, slender decks giving a light aesthetic impression and durability assured by post tensioned concrete. The paper presents the first in Poland stress Ribbon Bridge constructed last year. A static and dynamic analyse of the model is presented as well as construction solutions which were used to achieve the highest durability. The bridge was checked during static and dynamic load test. The results of this prove test were compared with results obtained from examination and study of other different bridge structures. It confirmed that the bridge has good dynamic resistance and greater stiffness than assumed in the design.