Applying Digital Technologies Beyond Design Life

This paper focuses on Floating Production Installations, which are assets designed based on site-specific environmental conditions to determine their design service life. The longevity of these assets depends on the fatigue aspects related to the structural elements and mooring systems. Among the challenges involving the continued services of ageing assets is the integrity of these elements. When an asset reaches its end of design service life, Operators often decide to undergo a life extension process for safe continued operations. Alife extension process generally includes three phases: investigation, determination and implementation. Following a baseline inspection to determine the present conditions of the structures, engineering assessments are to be carried out to evaluate the fatigue damage through the lifecycle of the installation and therefore determine the remaining fatigue life. Collecting information to execute these assessments is challenging and can be automated with the use of digital technology. Digital tools allow an accurate collection of data, providing a continuous evaluation of the remaining fatigue life and supporting an informed decision-making process. Observing the operation of several aging assets and their structural behaviour, the parameters to be measured during the installation's lifecycle have been identified along with other aspects that also contribute to the determination of its continued service. The recommended data acquisition for relevant measurements is summarized in this paper. The application of sensors and monitoring systems on the installations allows measuring these parameters on a continuous basis, and consequently, Operators are able to determine the degradation pattern that the structure is subject to. An estimation of the remaining fatigue life can be achieved by using predictive analysis, which, along with insights of the future expected corrosion, provides Operators the necessary basis to implement corrective measures and mitigations to avoid the occurrence of a failure. This paper offers an innovative, forward-looking technology that allies physics-based processes with digital technology, supported by predictive analytics and continuous structural evaluation, to assess the integrity of an offshore asset in support of safe continued services.

Justifying the prolongation of the service life of the bearing structure of a tank car when using Y25 bogies

This paper substantiates the use of Y25 bogies under tank cars in order to prolong their service life. The reported study has been carried out for a tank car with rated parameters, as well as the actual ones, registered during full-scale research. Mathematical modeling was performed to determine the basic indicators of the tank car dynamics. The differential equations of motion were solved by a Runge-Kutta method using the Mathcad software package (USA). It was established that the use of Y25 bogies under a tank car with rated parameters could reduce the acceleration of its bearing structure by almost 39 % compared to the use of standard 18‒100 bogies. Applying the Y25 bogies under a tank car with the actual parameters reduces the acceleration of its load-bearing structure by almost 50 % compared to the use of standard 18‒100 bogies. The derived acceleration values were taken into consideration when calculating the bearing structure of a tank car for strength. The calculation was performed using the SolidWorks Simulation software package (France). The resulting stress values are 18 % lower than the stresses acting on the load-bearing structure of a tank car equipped with 18‒100 bogies. For the load-bearing structure of a tank car with the actual parameters, the maximum equivalent stresses are 16 % lower than the stresses when the 18‒100 bogies are used. The design service life of the load-bearing structure of a tank car was estimated taking into consideration the use of Y25 bogies. The calculations showed that the design service life of the bearing structure of a tank car equipped with Y25 bogies is more than twice as high as that obtained for 18‒100 bogies. The study reported here would contribute to compiling recommendations for prolonging the service life of the load-bearing structures of tank cars

Improving Performance And Durability Of Concrete

Concrete is a porous material with different size of pores and cracks. Even the high quality concrete is a porous material which can pass the water through its cement paste. Porosity of the concrete can affect the natural performance of the concrete structure. Usually the water that comes from the environment contains the soluable contaminates which may initiate the reaction with the concrete materials and reduce the serviceability and design service life of the concrete. Durable structures to withstand significant deterioration can help to reduce the maintenance problem and conserves energy, money, materials and resources. The purpose of this research is to determine the major durability problem of concrete structure. The effects of critical environment deterioration such as sulfate and chloride attack was studied. Also the use of recycle and new material that might offset the destructive effects of environment attack to improve the durability or reduce the permeability was investigated.

Improving Performance And Durability Of Concrete

Concrete is a porous material with different size of pores and cracks. Even the high quality concrete is a porous material which can pass the water through its cement paste. Porosity of the concrete can affect the natural performance of the concrete structure. Usually the water that comes from the environment contains the soluable contaminates which may initiate the reaction with the concrete materials and reduce the serviceability and design service life of the concrete. Durable structures to withstand significant deterioration can help to reduce the maintenance problem and conserves energy, money, materials and resources. The purpose of this research is to determine the major durability problem of concrete structure. The effects of critical environment deterioration such as sulfate and chloride attack was studied. Also the use of recycle and new material that might offset the destructive effects of environment attack to improve the durability or reduce the permeability was investigated.

Influence of the porosity structure of road concrete on its durability

Cement-concrete pavements of roads and airfields are the most durable type of pavement. The design service life of cement-concrete pavements is 40-50 years, in Russia this period is 20-25 years, and for asphalt-concrete pavements is 10-15 years. The real, actual overhaul period of asphalt concrete pavements, is much lower than the design one (according to the Federal Road Agency of Russia «Rosavtodor», on average, 3-5 years or even less), therefore, work aimed at increasing the durability of cementconcrete pavements is of particular relevance. The main technical parameters of road concrete that characterize its durability are compressive strength, flexural tensile strength, water absorption and others. The most important parameter is the frost resistance of concrete, which is primarily influenced by the structure of the pore space. This paper shows the way of obtaining concretes based on aggregates, the frost resistance of which is lower than the frost resistance of the resulting concrete.

Static and fatigue testing using the same full-scale transport aircraft structure

The entire cycle of strength tests of the aircraft structure requires large expenditures of time and effort attributed to the manufacture of two full-size aircraft structures and two test rigs. The pace of development of modern aviation technology dictates strict requirements for timing and quality of testing, which allows us to ensure competitiveness in the world aircraft market. Therefore, when conducting a full cycle tests, shortening of the testing period becomes of particular importance. We consider a novel approach to strength testing of a full-scale transport aircraft structure which consists in static and fatigue tests carried out on the same object. The developed approach was tried out when testing the full-scale wing structure of a transport aircraft. The tests were carried out on a set-up that allowed reproducing both cases of static loading and variable loads of flight cycles. At the first stage, the static strength was proved by the results of finite-element calculation of the stress state of the structure at ultimate loads using a model verified by the strain measurements of one of the wing consoles under limit loads, as well as by testing typical and critical airframe elements. Samples of full-scale panels were additionally tested for buckling to confirm the load capacity of the upper wing panels. Fatigue tests were carried out in the time span of two design service life. The obtained results showed the possibility of conducting both static and fatigue tests using one and the same full-scale aircraft structure.

Effect of Fibers on Durability of Concrete: A Practical Review

This article reviews the literature related to the performance of fiber reinforced concrete (FRC) in the context of the durability of concrete infrastructures. The durability of a concrete infrastructure is defined by its ability to sustain reliable levels of serviceability and structural integrity in environmental exposure which may be harsh without any major need for repair intervention throughout the design service life. Conventional concrete has relatively low tensile capacity and ductility, and thus is susceptible to cracking. Cracks are considered to be pathways for gases, liquids, and deleterious solutes entering the concrete, which lead to the early onset of deterioration processes in the concrete or reinforcing steel. Chloride aqueous solution may reach the embedded steel quickly after cracked regions are exposed to de-icing salt or spray in coastal regions, which de-passivates the protective film, whereby corrosion initiation occurs decades earlier than when chlorides would have to gradually ingress uncracked concrete covering the steel in the absence of cracks. Appropriate inclusion of steel or non-metallic fibers has been proven to increase both the tensile capacity and ductility of FRC. Many researchers have investigated durability enhancement by use of FRC. This paper reviews substantial evidence that the improved tensile characteristics of FRC used to construct infrastructure, improve its durability through mainly the fiber bridging and control of cracks. The evidence is based on both reported laboratory investigations under controlled conditions and the monitored performance of actual infrastructure constructed of FRC. The paper aims to help design engineers towards considering the use of FRC in real-life concrete infrastructures appropriately and more confidently.

Determining Criteria for Assessment of RC Structures Affected by Carbonation-Induced Corrosion

The construction industry is now facing expanding and extensive activities in the area of assessing and retrofitting buildings and bridges that aligns with the sustainable construction strategy. These activities recognise the importance of extending the life of existing construction works thereby delivering environmental, economic and socio-political benefits. Reinforced concrete structures and their reliability are currently receiving considerable attention as a significant part of these structures reaches the design service life. Degradation processes such as carbonation- and chloride-induced corrosion have a major influence on the reliability and serviceability of concrete structures. The submitted study is primarily focused on reinforced concrete structures whose main degradation factor is carbonation of the concrete cover. Examples of such structures are cooling towers or industrial chimneys. Structures in the power industry are usually designed for service life of 40 years. Carbonation-induced corrosion results in visible cracks and unacceptable spalling of concrete cover. The aim of the study is to improve predictions of carbonation-induced corrosion propagation and to critically compare the criteria for degradation level assessment used in practice. The probabilistic analysis is based on measurements of concrete cover and carbonation depths and continuous observations of signs of corrosion on structural surfaces. The example of an industrial chimney shows that the limit of a severe failure, which requires (possibly repeated) minor repairs, is exceeded after about 17 years. The critical failure limit (30% of structural surface with visible signs of corrosion) is reached after 50 years, which seems to be sufficient as it is after 10 years than the usual design service life.