Shear friction strength of monolithic concrete interfaces

YesThis paper presents an integrated model for shear friction strength of monolithic concrete interfaces derived from the upper-bound theorem of concrete plasticity. The model accounts for the effects of applied axial stresses and transverse reinforcement on the shear friction action at interfacial shear cracks. Simple equations were also developed to generalize the effectiveness factor for compression, ratio of effective tensile to compressive strengths and angle of concrete friction. The reliability of the proposed model was then verified through comparisons with previous empirical equations and 103 push-off test specimens compiled from different sources in the literature. The previous equations considerably underestimate the concrete shear transfer capacity and the underestimation is notable for the interfaces subjected to additional axial stresses. The proposed model provides superior accuracy in predicting the shear friction strength, resulting in a mean between experimental and predicted friction strengths of 0.97 and least scatter. Moreover, the proposed model has consistent trends with test results in evaluating the effect of various parameters on the shear friction strength

Flood fragility analysis for bridges with multiple failure modes

Bridges are one of the most important infrastructure systems that provide public and economic bases for humankind. It is also widely known that bridges are exposed to a variety of flood-related risk factors such as bridge scour, structural deterioration, and debris accumulation, which can cause structural damage and even failure of bridges through a variety of failure modes. However, flood fragility has not received as much attention as seismic fragility despite the significant amount of damage and costs resulting from flood hazards. There have been few research efforts to estimate the flood fragility of bridges considering various flood-related factors and the corresponding failure modes. Therefore, this study proposes a new approach for bridge flood fragility analysis. To obtain accurate flood fragility estimates, reliability analysis is performed in conjunction with finite element analysis, which can sophisticatedly simulate the structural response of a bridge under a flood by accounting for flood-related risk factors. The proposed approach is applied to a numerical example of an actual bridge in Korea. Flood fragility curves accounting for multiple failure modes, including lack of pier ductility or pile ductility, pier rebar rupture, pile rupture, and deck loss, are derived and presented in this study.ope

Influence of highway 3D coordination on drivers' perception of horizontal curvature and available sight distance

"This paper is a preprint of a paper submitted to [journal] and is subject to Institution of Engineering and Technology Copyright. If accepted, the copy of record will be available at IET Digital Library"Drivers' road perception is an important human factor of comfort and safety on driving. Available sight distance of crest vertical curves superimposed on horizontal curves can be geometrically optimised by applying 3D coordination criteria. However, drivers might not perceive available sight distance improvements. Two approaches were used to investigate the effect of geometrical optimised design on perceived sharpness and visibility of isolated crest vertical curves overlapped with horizontal curves. A survey-based approach was used to evaluate subjective perception of 100 drivers. Three-dimensional renderings were displayed to subjects; who were asked to rank the curves by sharpness and sight distance. Moreover, 50 of those drivers previously participated on a driving simulation experiment involving the same curves, so objective driving data were collected too. Drivers' survey results indicate that driver's curve perception depends on the algebraic difference of grades while coordination of vertical and horizontal curves does not appear to affect this perception. On the other hand, the operating speeds on different curves were not statistically different from each other. Surprisingly, the operating speeds on a flat curve tended to be lower than on the vertical crest curves superimposed on the same horizontal curve. Likely causes are discussed in the paper.Moreno Chou, AT.; García García, A.; Camacho Torregrosa, FJ.; Llorca Garcia, C. (2013). Influence of highway 3D coordination on drivers' perception of horizontal curvature and available sight distance. IET Intelligent Transport Systems. 7(2):244-250. doi:10.1049/iet-its.2012.0146S24425072Hassan, Y., & Easa, S. M. (2000). Modeling of Required Preview Sight Distance. Journal of Transportation Engineering, 126(1), 13-20. doi:10.1061/(asce)0733-947x(2000)126:1(13)García, A. (2004). Discussion of «Optimal Vertical Alignment Analysis for Highway Design» by T. F. Fwa, W. T. Chan, and Y. P. Sim. Journal of Transportation Engineering, 130(1), 138-138. doi:10.1061/(asce)0733-947x(2004)130:1(138)Bidulka, S., Sayed, T., & Hassan, Y. (2002). Influence of Vertical Alignment on Horizontal Curve Perception: Phase I: Examining the Hypothesis. Transportation Research Record: Journal of the Transportation Research Board, 1796(1), 12-23. doi:10.3141/1796-02Hassan, Y., Sayed, T., & Bidulka, S. (2002). Influence of Vertical Alignment on Horizontal Curve Perception: Phase II: Modeling Perceived Radius. Transportation Research Record: Journal of the Transportation Research Board, 1796(1), 24-34. doi:10.3141/1796-03Hasan, M., Sayed, T., & Hassan, Y. (2005). Influence of vertical alignment on horizontal curve perception: effect of spirals and position of vertical curve. Canadian Journal of Civil Engineering, 32(1), 204-212. doi:10.1139/l04-090Wang, F., & Easa, S. M. (2009). Validation of Perspective-View Concept for Estimating Road Horizontal Curvature. Journal of Transportation Engineering, 135(2), 74-80. doi:10.1061/(asce)0733-947x(2009)135:2(74)Bella, F. (2007). Parameters for Evaluation of Speed Differential. Transportation Research Record: Journal of the Transportation Research Board, 2023(1), 37-43. doi:10.3141/2023-05Ben-Bassat, T., & Shinar, D. (2011). Effect of shoulder width, guardrail and roadway geometry on driver perception and behavior. Accident Analysis & Prevention, 43(6), 2142-2152. doi:10.1016/j.aap.2011.06.004Jia, L., Wang, J., & Lu, M. (2011). Using real-world data to calibrate a driving simulator measuring lateral driving behaviour. IET Intelligent Transport Systems, 5(1), 21-31. doi:10.1049/iet-its.2009.0094Antonson, H., Mårdh, S., Wiklund, M., & Blomqvist, G. (2009). Effect of surrounding landscape on driving behaviour: A driving simulator study. Journal of Environmental Psychology, 29(4), 493-502. doi:10.1016/j.jenvp.2009.03.005Land, M. F., & Lee, D. N. (1994). Where we look when we steer. Nature, 369(6483), 742-744. doi:10.1038/369742a0Zuriaga, A. M. P., García, A. G., Torregrosa, F. J. C., & D’Attoma, P. (2010). Modeling Operating Speed and Deceleration on Two-Lane Rural Roads with Global Positioning System Data. Transportation Research Record: Journal of the Transportation Research Board, 2171(1), 11-20. doi:10.3141/2171-02Kweon, B.-S., Ellis, C. D., Lee, S.-W., & Rogers, G. O. (2006). Large-Scale Environmental Knowledge. Environment and Behavior, 38(1), 72-91. doi:10.1177/001391650528009

A numerical investigation on the fire response of a steel girder bridge

The response of bridges subject to fire is an under researched topic despite the number of bridge failures caused by fire. Since available data shows that steel girder bridges are especially vulnerable to fire, this paper delves into their fire response by analyzing with a 3D numerical model the response of a typical bridge of 12.20 m span length. A parametric study is performed considering: (1) two possibilities for the axial restraint of the bridge deck, (2) four types of structural steel for the girders (carbon steel and stainless steel grades 1.4301, 1.4401, and 1.4462), (3) three different constitutive models for carbon steel, (4) four live loads, and (5) two alternative fire loads (the hydrocarbon fire defined by Eurocode 1 and a fire corresponding to a real fire event). Results show that restraint to deck expansion coming from an adjacent span or abutment should be considered in the numerical model. In addition, times to collapse are very small when the bridge girders are built with carbon steel (between 8.5 and 18 min) but they can almost double if stainless steel is used for the girders. Therefore, stainless steel is a material to consider for steel girder bridges in a high fire risk situation, especially if the bridge is located in a corrosive environment and its aesthetics deserves special attention. The methodology developed in this paper and the results obtained are useful for researchers and practitioners interested in developing and applying a performance-based approach for the design of bridges against fire. © 2012 Elsevier Ltd. All rights reserved.Funding for this research has been provided to Dr. Paya-Zaforteza by the Spanish Ministry of Education (contract number EX-2008-0669 of the Program for Postdoctoral Stays), the Spanish Ministry of Economy and Competitiveness (research project BIA 2011-27104) and the Universitat Politecnica de Valencia (Research and Development Support Program PAID-06-11). Funding has also been provided to Dr. Maria Garlock by the National Science Foundation (NSF) under award number CMMI-1068252. All opinions expressed in this paper are the authors' and do not necessarily reflect the policies and views of the sponsors.Paya-Zaforteza, I.; Garlock, ME. (2012). A numerical investigation on the fire response of a steel girder bridge. Journal of Constructional Steel Research. 75:93-103. https://doi.org/10.1016/j.jcsr.2012.03.012S931037

Cement stabilisation of crude-oil-contaminated soil

© 2016, Thomas Telford Services Ltd. All rights reserved. Crude-oil-contaminated soils are usually considered unsuitable construction materials for earthworks. This paper presents an experimental investigation of the effects of applying Portland cement on the plasticity, strength and permeability of a crude-oil-contaminated soil in order to ascertain its suitability for use as an earthworks construction material. Series of specific gravity, Atterberg limits, compaction, strength and permeability characteristics were determined for a natural soil, the soil after being artificially contaminated with crude oil and the contaminated soil with varying proportions of added cement. It was found that the geotechnical properties of the soil became less desirable after contamination with crude oil, but the application of cement to the contaminated soil improved its properties by way of cation exchange, agglomeration and cementation. Cement stabilisation of crude-oil-contaminated soil provides a stable supporting structure, as well as a capping layer, that prevents the crude oil from interacting with the construction materials above. Thus, instead of disposing of contaminated soils, creating unnecessary waste and incurring costs, stabilisation with cement – which is practically feasible to undertake on site – makes such soils useful for supporting structural foundations or road pavement structures

Main flexible pavement and mix design methods in Europe and challenges for the development of an european method

Pavement and mix design represent one of the key components within the life cycle of a road infrastructure, with links to political, economic, technical, societal and environmental issues. Recent researches related to the characteristics of materials and associated behavior models both for materials and pavement, made it appropriate to consider updating current pavement design methods, and especially in the USA this has already been in process while in Europe uses of the methods developed in the early 1970s. Thus, this paper firstly presents a brief historical overview of pavement design methods, highlighting early limitations of old empirical methods. Afterwards, French, UK and Shell methods currently in use in Europe will be presented, underlining their main components in terms of methodology, traffic, climatic conditions and subgrade. The asphalt mix design and modeling in Europe are presented with their inclusion in the pavement design methods. Finally, the main challenges for the development of a European pavement design method are presented as well as the recent research developments that can be used for that methodThe second author would like to express the support of Portuguese National Funding Agency for Science, Research and Technology (FCT) through scholarship SFRH/BSAB/114415/ 2016. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.info:eu-repo/semantics/publishedVersio

Mechanical, durability and microstructure properties of cold asphalt emulsion mixtures with different types of filler

The primary aim of this study is to investigate the enhancement of Cold Asphalt Emulsion Mixtures (CAEMs) using binary and ternary blended fillers (BBF and TBF), including an in-depth assessment of the microstructure. Ordinary Portland cement (OPC), fly ash (FA) and ground granulated blast furnace slag (GGBS) were used for the BBF while silica fume (SF) was added to the BBF to obtain TBF. The mechanical and durability results indicated that the TBF was more suitable than the BBF for the production of CAEMs. The microstructural assessment indicated that the effect of BBF on the internal microstructure of CAEMs was slightly negative and more noticeable in CAEMs containing FA. It is proposed that the addition of SF to BBF mixtures can eliminate the delay in formation of hydration products caused by the bitumen emulsion. Overall, the research suggests that the use of BBF-CAEMs might be appropriate for pavements in cold climate whereas TBF-CAEMs would be effective in road pavements exposed to severe conditions both in hot and cold climates