A knowledge-based system for maintenance planning of highway concrete bridges

This paper presents a knowledge-based system that is used for maintenance planning of highway concrete bridges. The system includes functions for maintenance priority setting among bridges, feasible treatment assessment in each case, and maintenance planning for a bridge stock. Maintenance priorities are set using a scoring model with decision parameters appropriately weighted. Feasible treatments are determined based on bridge condition and other factors that accelerate deterioration. Decisions for maintenance planning result from a linear programming model and are based on priority ranking, cost and effectiveness characteristics of feasible treatments, and existing budget constraints. The system has been successfully evaluated with actual and simulated data.     

Debonding- and Fatigue-Related Strain Limits for Externally Bonded FRP

Available guidance for mitigating debonding failure of externally bonded fiber reinforced polymer (FRP) composites applied to concrete is evaluated based on data obtained from large- and full-scale experimental programs. Current recommendations are inadequate to effectively mitigate intermediate crack-induced debonding in flexural members. An improved, although still simple to apply, equation for determining limiting FRP material properties to mitigate debonding is presented and evaluated. Additionally, the effect of fatigue loading on the debonding behavior of externally bonded FRP is not adequately addressed in practice. In the limited data presented, a degradation of bond behavior is observed even under fatigue loading conditions amounting to an FRP stress range of no more than 4% of the FRP capacity.     

Exploring Concrete Slump Model Using Artificial Neural Networks

Fly ash and slag concrete (FSC) is a highly complex material whose behavior is difficult to model. This paper describes a method of modeling slump of FSC using artificial neural networks. The slump is a function of the content of all concrete ingredients, including cement, fly ash, blast furnace slag, water, superplasticizer, and coarse and fine aggregate. The model built was examined with response trace plots to explore the slump behavior of FSC. This study led to the conclusion that response trace plots can be used to explore the complex nonlinear relationship between concrete components and concrete slump.     

Comparative study on strength,sorptivity, and chloride ingress characteristics of air-cured and water-cured concretes modified with metakaolin

This paper reports an investigation in which the performance of plain and metakaolin (MK)-modified concretes were studied under two different curing regimes. The purpose of this study is to evaluate the effectiveness of MK in enhancing the strength and permeation properties of concrete. MK was used to replace 0–20% of Portland cement by weight in concrete with two water-binder (w/b) ratios of 0.35 and 0.55. The change in compressive strength, sorptivity, and chloride ingress with age at all cement replacement levels under both air and water curing are compared with those of the control concrete. The results indicated that the inclusion of MK greatly reduced sorptivity and chloride permeability of concrete in varying magnitudes, depending mainly on replacement level of MK, w/b ratio, curing condition, and chloride exposure period. It was found that under the inadequate or poor curing, MK-modified concretes suffered a more severe loss of compressive strength and permeability-related durability than the plain concretes.     

钢筋轻骨料混凝土剪力墙的试验研究

通过７个粉煤灰陶粒硷和一个普通砼单片剪力培的试验，研究了在低周反复荷载作用下轻骨料砼剪力墙的强度和变形性能，并与同类普通检剪力墙进行了比较和分析．试验表明，轻骨料砼剪力墙的受力性能和破坏形态与普通砼剪力墙相似，但能量耗散能力和延伸性优于普通砼剪力墙．在试验的基础上，建立了界限剪跨比的判别式，强度控制区的划分条件，提出了抗剪强度计算方法．建议方法的计算值与本次试验及国内外其它资料的结果有较好的吻合程度．本文还对剪力墙位移计算和控制，达到极限强度时的刚度退化率提出了见解．     

碳纤维粘贴混凝土试件锚固长度的试验研究

将碳纤维粘贴在混凝土试件上，对其锚固长度进行试验研究，并对试验结果进行分析，从中找出了对应各种混凝土强度的锚固长度值，寻出其规律，对碳纤维锚固长度的取值和影响锚固长度的因素进行分析，提出了碳纤维锚固长度建议值，供工程应用参考。     

坝体—库水相互作用的流固耦合分析

采用Ansys中的声学流体单元模拟库水,进行了某重力坝与库水的流固耦合分析。考虑了库底吸收系数对坝库耦合系统动力响应的影响,计算结果表明：库底吸收性显著降低了动水压力,吸收系数越大,效果越明显;位移反应也有所减小。比较了Ansys与Adina的计算结果及效率,结果表明：两者的计算结果基本一致,Adina的计算效率高于Ansys,但Ansys的前后处理较Adina高效。     

浅谈施工过程中混凝土温度裂缝的预防与控制

本文阐述了混凝土温度裂缝产生的原因,提出了施工过程中的综合预防措施。     

Simplified Model for Compressive Behavior of Concrete Columns Strengthened by Steel Angles and Strips

This paper presents an analytical model to determine the compressive response of concrete members, having a square transverse cross section and reinforced with steel angles at the corners and steel strips connecting the steel angles. The model evaluates the effects of transverse strips and steel angles on confinement pressures, including strength and buckling phenomena. Compressive response was evaluated in cases of directly and indirectly loaded elements. The data produced correlate well with available experimental data.     

横山土石坝扩建的构造和应力变形分析

本文对１９９５年１２月已竣工验收鉴定的横山扩建坝的构造、主要特点和评价作了概要介绍。重点说明了扩建成混凝土面板堆石坝的设计要点和理论方法、老坝心墙拱效应、深混凝土防渗墙的应力状况。结合原型内部观测成果，作了对比分析研究。