Available online at www.sciencedirect.com
ScienceDirect Transportation Research Procedia 20 (2017) 596 – 601
12th International Conference "Organization and Traffic Safety Management in large cities", SPbOTSIC-2016, 28-30 September 2016, St. Petersburg, Russia
Evaluation of the Effectiveness of the Method for Calculation of Composite Materials in the Construction of the Bridges in Terms of Their Safety and Reliability Viktor Shendrik 1a*, Pyotr Druzhinin 2, Orifdzhon Bobobekov 3b 1 2
Saint Petersburg State University of Architecture and Civil Engineering, 4 2nd Krasnoarmeyskaya str., Saint Petersburg, 190005, Russia Military (Engineering) Institute of the Military Academy of Logistics and Transport named after Army General Khrulyov A.V., 8 Makarova embankment, Saint Petersburg, 199034, Russia 3 Tajikistan University of Technology, 10 akademiki Radzhabovyh str., Dushanbe, 734042, Tajikistan
Abstract The article reveals the problem of applying composites to bridgework abutments. The advantages of composites over traditional materials are described. The examples of existing structures made of composites are presented. The article reports the problem related to the composite bridgework abutments construction. The goal of undertaken study is set. Testing of composite samples potentially suitable for bridgework abutments construction is reported. 2016The TheAuthors. Authors. Published by Elsevier © 2017 Published by Elsevier B.V.B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of the 12th International Conference "Organization and Traffic Peer-review under responsibility of the organizing committee of the 12th International Conference “Organization and Traffic Safety Safety Management in large cities". Management in large cities” Keywords: traffic structures reliability; bridgework on motorways; bridgework abutments; calculation procedure; structures lifecycle; composites; testing
1. Main text Traffic safety depends not only on motorways condition but on the relevant structures as well. Guaranteed reliability of traffic structures is the cornerstone of traffic safety. The responsibility for building a traffic structure is
* Corresponding author. Tel.: +0-000-000-0000 ; fax: +0-000-000-0000 . E-mail address:
[email protected] a*,
[email protected] b
2352-1465 © 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of the 12th International Conference “Organization and Traffic Safety Management in large cities” doi:10.1016/j.trpro.2017.01.096
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extremely high. As a rule, they are erected over obstacles bearing risks for humans. There is a problem as to the reliability of artificial structures on motorways during their lifecycle. This becomes even more important with urban structures for population density in cities is times higher. In this country column bents had been built since 1960s with use of reinforced concrete shell piles with diameter 0.8…1.0 m, bridge link stretch up to 8 m, wall thickness 10–12 cm. Later sections having length up to 12 m and diameter 1.6 m appeared. Shell piles links were connected with bolts with use of flange joints. The lower part of shells was filled with concrete to the level of 3 m to provide bearing capacity, and the upper part was filled with non-wettable sand to the level of possible fluctuation of water horizon to exclude any possibility of rupture by freezing water. The advantages are as follows: no need for grillage erection and material consumption decrease [Salamakhin (2014)]. However, oftentimes such abutments being operated for a little time show vertical cracks. This is caused by imperfection of a structure, as shell armoring is not designed for side impacts on shell walls; concrete strength for such structure is not sufficient. Thus, the study subject is bridgework abutments. In recent times, reinforced concrete and metal traditionally used in construction have been being actively replaced with composites. The very idea of a composite (compositional, combined) is rather wide-ranging and relates to all materials consisting of two and more components, e.g. reinforced concrete, glass, glued wood, etc. However, currently this word is more often understood as certain innovative materials which just a while ago have been used in rather narrow industries such as space or aviation. As these materials contain several components with different properties, they combine properties of all constituents though not in full. This advantage favorably sets composites apart from traditional construction materials. It gives the possibility of improving existing structures, create new ones and produce hybrid systems enhancing reliability of famous structural solutions for the combination of various properties. The properties associated with composite structure purpose are formed in the course of structure manufacturing, which gives actually endless prospects through the possibility of structure and composition modification. Besides, one of the main directions of USSR economic development as long ago as in 1986–1990 and for the period till 2000 was the structural improvement of applied construction structures and materials with use of plastics, resins, polymers, and other non-metal materials. More than two decades later, we still call them innovative ones [Bondarenko and Shagin (1987)]. It means that on the one hand the study context is still broad, on the other hand it is required to make up for lost time and expand the range of produced goods and structures and composite structures in this country. Composites are characterized by a series of peculiarities. The constituents and mutual disposition scheme are to be determined in advance. The appearance and quantitative composition of components are selected with consideration of required properties of a designed item. The resulted material appearing homogeneous in macroscale is non-homogeneous in microscale; the constituents have different properties and in joint points there is a boundary — a layer between phases [Shevchenko (2010)] also influencing the resulted item operation characteristics. Components differ in geometric sizes. A non-continuous component split in the composition is called armoring element or filler. The component continuously filling the whole volume is called matrix which may be represented by metals, alloys, organic and non-organic polymers and other substances. An armoring element is usually represented by evenly spread fine particles (to 2–4% of the whole substance volume), or fibers of materials of various nature mainly high-strength ones. In fiber composites, the share of high-strength fibers may reach 75%. In the course of fiber composites production the tendency is to evenly spread armoring fibers to provide uniform resistance to impact loads across an entire section. Essentially, in fiber composites an armoring element is envisaged in one direction, therefore such composites vividly demonstrate anisotropy of properties [Arzamassov (2008)]. That is to say that such materials have different resistance to loads depending on the impact direction and fibers disposition. Mechanical properties of fiber composites are very good for construction use. Among the main characteristics are high strength of armoring fibers, bonding strength on the interphase boundary and matrices rigidness. These very characteristics determine the mechanics of operation and fracture of such materials. Thus, in the course of design it is required to form an optimal structure of the material itself. As for the interphase boundary, the imperative requirement to this part of the material is resistance to stresses and impacts considering their assignment in a construction structure. The bases for composite materials used in different industries are represented by various fiberglass plastics; basalt fiber reinforced polymers and carbon fiber-reinforced plastics are less spread for a higher cost [Oreshkin (2014)].
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Fiberglass plastics for its low cost and good strength values appear to be the most perspective composites and successfully used in construction.
Fig. 1. The footbridge Bradkirk (on the left) and overbridge above the railroad Staden Hay (on the right) with use of composites.
Even now, our foreign colleagues have implemented a number of projects of structures made exactly of fiber composites. The first bridgework with incorporation of composite elements into structural elements of superstructures will turn ten years soon. On UK railroads the reinforcement of more than 30 bridgeworks is completed; four bridgeworks are built from the ground up, aqueducts are being built [Kendall (2010)]. Initially, composites were used for construction of pedestrian bridgework. Prefabricated structures had small weight which provided advantages mainly as to the cost of erection works and transportation to a construction site. The design solution for the bridge Bradkirk made of polymers armored with fibers is recognized as a cost effective one versus the metal superstructure (Fig. 1). One of the first highway structures is the overbridge above the railroad in the UK appeared in the course of replacing the structure Staden Hay which consisted of metal beams and wooded deck. The small superstructure 9.1 m long and 4 m wide was replaced with the fiberglass plastic structure. Predominantly short span bridgework made of polymers armored with fiberglass plastics and carbon fiberreinforced plastics are popular in Holland; one of the most popular projects by Fibercore (Fig. 2) made of fiberglass plastics by mold pressing. In 2009 only, this manufacturer made 23 structures of such type related to the class of small structures and the demand for them is growing now.
Fig. 2. A small footbridge by Fibercore.
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Fig. 3. The overbridge with superstructure made of formed FRP by Acciona Infrastructuras, Spain.
In Spain, various hollow main beams systems of superstructures made of a hybrid material by mold pressing (carbon and fiberglass). Such pre-fabricated structures are called prepregs. Inside them, the armoring material — carbon filler — is soaked with epoxy adhesive for strengthening — this way a composite is created [Kendall (2011)]. On top of these main beams, a cast-in-place concrete carriageway slab (deck) is installed (Fig. 3). In the opinion of foreign specialists who conducted the studies, the combination of the engineering thought and green ecologically safe technologies is the XXI century reality. The environmental influence of composites made of polymers armored with fiberglass and carbon fiber is much less [Hamrick (2012)]. Environment protectors were satisfied having checked the ecological indices of polymeric materials armored with fiberglass and carbon glass and spoke for their further countrywide implementation. The above-mentioned examples represent only a small part of overseas structures made of composites. One of the composite advantages is that in this case the material and the structure are fabricated concurrently therefore being aware of the required characteristics it is quite possible to manufacture e.g. bridge abutments. In this country, structures made of composites are also used in bridge structures; the most active developers here are ApATeCh and Ruscompozit (Fig. 4). Hybrid structures of superstructures, decking, barrier railings, etc. are proposed.
Fig. 4. The footbridge, near s. Pyra, 378th km of the highway М7 “Volga” (ApATeCh on the left) and the footbridge, 250th km of the highway М1 “Belarus” (Ruscompozit on the right).
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In 2015 on the motorway “Krasny Yar-Sosnovka” over the river Pashenka in the Novosibirsk Oblast the first automobile bridge made of polymers 18 m long was opened in this country. This is a serious step forward, for earlier in this country bridgeworks with bearing structures made of innovative materials accounting for automobile load have not been built while the world accounts for about 400 of them. As one can see from the built structures, application of composites even in bearing structures of bridgework superstructures is growing dynamically enough. Application of innovative materials in bridgework abutments is less dynamic. It is also associated with abutments peculiarities: possible location in wet or aggressive environment, high loads on abutments as compared to superstructures. In addition, application of composites is influenced by their functioning specificity: dependence on the location and direction of fibers, peculiarities of material functioning in transversal and longitudinal directions. Nevertheless, active work in this direction is being conducted in this country as well as in European countries, the USA, and China. In particular, Chinese colleagues develop and experimentally check hybrid structures of trestle bents which show good values at various impacts including calculated seismic one as well [ElGawady and Dawood (2011, 2012)]. Composite abutments are to be implemented subsequently, for structure reliability directly depends on the condition and reliability of abutments. For a start, it is advisable to manufacture abutments for bridgework not intended for watercourse and significant loads but for small overbridges and aboveground pedestrian crossings. When designing such structures, the loads imposed by watercourse, ice, and vessels are absent. The main existing abutments types are as follows: piles, poles, column bents, trestle bents, plate piers, mixed ones. To choose the most convenient and simple one it is better to begin with column bents, poles or pile abutments; these very types are mainly used for construction of overbridges and footbridges. For example, shelled abutments mentioned in the beginning of the article (those showing longitudinal cracks being operated for a little time) may be fortified with composites or it is required to create a hybrid structure from the very beginning incorporating composites and concrete/reinforced concrete. Proceeding from all the above-mentioned, the goal of this study is formed. The goal of this study is to elaborate the calculation procedure for abutments of bridgework made of composites. Structurally this work includes theoretical calculations, experimental research of models for checking loads and impacts, elaboration of the calculation procedure itself as to abutments, and practical recommendations for the implementation of structures abutments made of composites. The obtained characteristics of items will allow deciding if the existing calculation procedure is worth adaptation e.g. reinforced concrete shells calculations to be adapted to composite ones or it is worth performing the grounding anew. As bridgework with composite abutments does not exist, this study has a scientific novelty; moreover, exactly the non-availability of calculation procedure in the standards is the main reason for non-availability of such structures. The balance of the work is planned as the utility model patent development and application of the developed methods to the design of an actual facility. To reach the goal of the study some work has been already done. The department of automobile roads, bridges, and transport tunnels of St. Petersburg State University of Architecture and Civil Engineering tested hollow pipe samples made of composites. The completed testing stage included the vertical load impact on samples. Fiberglass samples by the two different manufacturers with wall thickness from 4 to 4.5 mm and four length values, namely 10 cm, 20 cm, 30 cm, and 40 cm underwent compression at Introns W-5196. The samples featured a slight difference in the manufacturing technology: company 1 providing the diameter 100 mm used a pultrusion method and company 2 providing the diameter 110 mm used a spinning method. The samples by company 1 showed a higher strength and endured a higher pressure; however, the nature of fracture was more fragile. The samples by company 2 though endured less load showed more plastic nature of fracture and smooth strength decrease, not by several times at once as compared to the first case. In general, the samples behavior under compression load showed that goods made of composites of both types could endure significant structural vertical loads; the further experimental studies will be conducted. In case the goal of the study is successfully reached, it is possible to enhance the reliability and durability and consequently safety of bridgework structures of this type on motorways. References
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