KOMPUTEROWE MODELOWANIE BETONOWYCH USTROJW INYNIERSKICH PDF

PWN ; Starosolski W., Komputerowe modelowanie betonowych ustrojów inżynierskich. Wybrane zagadnienia. Tom 1 i 2 Wydawnictwa Politechniki Śląskiej. Starosolski W.: Komputerowe modelowanie betonowych ustrojów inżynierskich, Sieczkowski J.: Podstawy komputerowego modelowania konstrukcji. P. Kossakowski, Inżynierski problem komputerowego modelowania pracy Komputerowe modelowanie betonowych ustrojów inżynierskich wybrane.

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The possibility of using foamed bitumen and moselowanie emulsion as binders in the composition of road bases makes it necessary to identify the influence of the binder type on the service life of these layers through dynamic tests.

Obtaining proper physical and mechanical parameters does not moddelowanie ensure the correct evaluation of the recycled base quality. Satisfaction of the quality-related requirements does not guarantee the provision of the required fatigue life parameters.

Cold recycled kompuyerowe with cement should work within the viscoelastic range due to hydraulic bonding in the structure. If this range is exceeded, a considerable rise in strains occurs as a result of brittle fracture, leading to the loss of fatigue life.

The paper presents the results from the fatigue tests of recycled bases. Beotnowych cement I 32,5R was applied as a binder. Fatigue tests were performed in compliance with the requirements of enclosure E of PN-EN at a constant normal stress of kpa, kpa and kpa. The results were used to compare the effects of the binder type applied to the recycled base and determine the service life in terms of the stress applied. Introduction Deep cold recycling technology is now a solution applied worldwide to the rehabilitation of distressed pavement layers [].

Proceedings of the STABILITY of STRUCTURES XIV-th SYMPOSIUM – PDF

Investigations into the influence of individual components and interaction between them on the quality and service life of RCM bases in terms of, for example, frost durability [9], effect of the bftonowych agent type [10, 11], possibility of using recycled aggregates, bitumen types, etc. The design in which RCM base quality assessment is inynierskiich only on conventional parameters, i.

Many researchers in the highway engineering area [] evaluate the quality of the recycled layers using fatigue life testing under cyclic loads controlled stress or strain.

Dynamic loads are more destructive in cement-based structural layers than in fully flexible layers. Exceeding the limiting values of indirect tensile modleowanie leads to cracking due to inadequate support of the layer relative to the load applied or, in extreme cases, to the overload.

Cyclic loads reduce structural capacity of the pavement, which results from the drop in elastic modulus and increase in strain [15, 16]. The location of the recycled base layer [17] within the structural system is also important, as is the design number of axles kn per design lane. Preliminary analyses [18] show that obtaining the required physical and mechanical parameters of the emulsion-based RCM base during the designing phase does not ensure providing the pavement structure with the required fatigue life.

Stress values from the computational model transferred to the laboratory simulation showed that the fatigue life criterion laid down in enclosure E of PN-EN was not met.

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inynierskkch With the above in Object of study To study the influence of the bitumen binder on the service life of the RCM base, the designed mineralcement mix had to meet the requirements for limit curves of base layers with foamed bitumen [7] and with bitumen emulsion [8] intended for the road under million axles kn [19].

The combination of components allowed a simulation of the use of waste material derived from a road pavement. To evaluate the fatigue life of the recycled base layer, samples were obtained and tested in a laboratory using the indirect tensile test ITT mofelowanie compliance with PN-EN Appendix E. To assess the impact of loading on the recycled base layer, the test was performed at constant stress levels.

The normal stress levels used in the tests were selected based on the literature data [18, 19] and preliminary calculations of computational models for typical layer systems in the road pavement structure laid on elastic subgrade.

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Three levels were selected to vary the load effect: The end of the test was tantamount to the failure of the specimen or to the completion of strain cycles at the constant stress value. These assumptions comply betonowyh the regulations as given in enclosure E to the PN-EN modelowaniw standard Mix design The mineral-cement mix design was prepared based on the technical guidelines and limit curves specified therein for the mix with foamed bitumen [7] and with komputerowr emulsion [8].

To provide the required aggregate grain size relative to the size of the Marshall mould, aggregates of sizes greater than Figure 1 shows the designed grading curve. The design amount and the applied amount of the foamed bitumen were equal, whereas the amount of the bitumen emulsion had to be adjusted by adding water in order to obtain modelowamie same amounts of bitumen in the base mix composition.

Thus the emulsion contents in inynirskich recycled base amounted to 5. Portland cement class Foaming characteristics of the bitumen betonowycn determined based on changes in water injection rate from 1. The test results indicated that the optimum content of water needed to foam the bitumen in question was 3. The next stage of the recycled base mix design included determination of the optimum water content needed to obtain the maximum density of the mineral skeleton using the Proctor method defined modelowani PN- EN The amount of water for the optimum moisture content was found to be 5.

The specimens were subjected to compressive semisinusoidal modelowane loading. A vertical diameter plane applied the load until the failure of the specimen. Normal stress values inynierskidh the centre of the specimen were kpa, kpa and kpa. Owing to varied specimen sizes and stress values, it was necessary to calculate the force, which induces stresses of equal value. The stress was calculated according to equation 1 with conversion to the value of the force sought.

Fatigue evaluation was represented as a change in strain level in the recycled base with respect to the binder used foamed bitumen and bitumen jnynierskich. Prior to mkdelowanie test, the specimens were conditioned for 4 hours at 20 O C. The classical approach was used for fatigue life estimation of the RCM in terms of the binder amount and type [23, 24]. Fatigue curves Figure 2 shows fatigue characteristics.

The fatigue plots are presented as a relationship between the number of loading cycles log and strain increase. Different fatigue progress was observed at the stress of beyonowych for the RCM with emulsion, and identical at kpa for the base with foamed bitumen. Also, the recycled base layer with foamed bitumen at kpa did not show any changes in fatigue life within cycles.

Analysis of fatigue curves of recycled bases made with foamed bitumen and bitumen emulsion at kpa indicated a decline in fatigue resistance before the completion of loading cycles. Fatigue curves of the recycled base layer with respect to the binder type and normal stress: Fatigue life evaluation Fatigue life estimation was performed with respect to assumptions of the conventional method, which determines fatigue failure after reaching the double of initial strain.

Proceedings of the STABILITY of STRUCTURES XIV-th SYMPOSIUM

Regression curves describe the fatigue failure at the set level of stress, and the results are summarised in Figure. The fatigue correlation curves of the recycled bases with foamed bitumen, regardless of the bitumen content, lie close to one another.

This betonoaych that the usgrojw bitumen content does not affect the fatigue life of the RCM base. Therefore, it can be stated that recycled base layers with foamed bitumen will work over a wider viscoelastic range with respect to the stress levels that occur in the base layer.

Conclusion Based on the analyses of fatigue life and fatigue characteristics of the recycled bases with foamed bitumen and bitumen emulsion, the following conclusions can be made: The type of the bitumen binder used does not affect the void space content in the recycled base layer.

Komluterowe base layers with foamed bitumen and bitumen emulsion have the same void space contents, which allows a comparison of the results from the tests of their physical and mechanical properties as well as fatigue resistance. The recycled cold base with foamed bitumen shows the higher indirect tensile strength at 25 O C usrrojw with the strength of the base with bitumen emulsion.

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This is probably due to the technology of lowering bitumen viscosity by bitumen dispersion in water and the need to add emulsifiers and stabilizers to the binder to stabilise the mix. Recycled modelosanie layers with foamed bitumen and bitumen emulsion at a low stress of kpa show similar changes of fatigue curves betonoywch do not show fatigue failure associated with the double increase in the initial strain value.

Higher resistance to fatigue in the mode of controlled stress is observed in the base layer made with foamed bitumen as a binder. Generation of high stresses equal to kpa changes the fatigue life of the base layer with foamed bitumen and leads to exceeding acceptable strain levels.

Specification development for cold in-situ recycling of asphalt. Construction and Building Materials,pp [2] Stimilli A. Performance evaluation of moedlowanie cold-recycled mixture containing high percentage of reclaimed asphalt, Road Materials and Pavement Design.

Application of foam bitumen in cold recycling and hydrated lime in airport pavement strengthening, Case Studies in Construction Materials.

August [5] Asphalt Academy, TG The effects of using foamed bitumen and bitumen emulsion in the cold recycling technology, 8th Inter. Environmental Engineering, Vilnius, Lithuania. Procedia Engineering, pp doi: An experimental study on fatigue properties of emulsion and foam cold recycled mixes, Construction and Building Materials 24pp [13] Underwood B.

A moedlowanie damage model for asphalt cement and asphalt mastic fatigue, International Komputerlwe. Field validation of recycled cold mixes viscoelastic properties.

Construction and Building Materials 75pp [15] Ameri M. A study on fatigue modeling of hot mix asphalt mixtures based on the viscoelastic continuum damage properties of asphaltbinder, Construction and Building Materialspp [16] Mannan U. Evaluation of the pavement performance, Bulletin of the Polish Academy of Sciences. Technical Sciences, 63 doi. Characteristics of the fatigue life IT-FT of the recycled betonoywch course at modleowanie controlled stresses state.

Analysis and design of flexible and semirigid pavement structures. Warszawa in Polish. Vademekum kationowych emulsji asfaltowych, IBDiM. Theory and Practice, third ed. Fatigue lives of asphalt beams in 2 and 4 point dynamic bendings testes based on a “new” fatigue life definition using the dissipated energy concept.

DWW, [25] Rowe G. Improved techniques to evaluate the fatigue resistance of asphalt mixture. The results of investigations and static strength analysis are provided. They were necessary to assess the reliability of the structure operating under chemical corrosion conditions corresponding to the XA exposure class. The repair plan, already implemented, together with selected components of the building structural upgrade design are presented.

Introduction Civil structures in operation are adversely affected by a number of factors, which in many cases can significantly reduce usability and even pose a risk to structural integrity. Standard [1] imposes a requirement for the durability of the structure.

Throughout its lifetime, the structure must meet the requirements on carrying capacity, stability and serviceability. Environmental actions on concrete structures and products are taken into account in standards [2, 3], which specify the exposure classes presented in Table 1.

Chemical corrosion is an action often found in real-life situations. However, because of the complexity of this phenomenon, it is not precisely specified in current standards. Apart from the fact that XA exposure classes are specified, a number of parameters usgrojw requirements are not accurately stated, which is discussed below. To achieve the required durability of iynnierskich structures and products, it is necessary to ensure that composition and quality of concrete are appropriate for the conditions of use, which correspond to individual exposure classes.

Minimum concrete parameters are specified in standard [2] for the assumed year lifespan of the structure. Table 2 shows the required parameters of concrete for XA exposure classes under chemical attack situation.