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This paper describes a study of the chloride content in the concrete lagging of prestressed concrete elements of the roof structure of an aluminium foundry building. Sources of chloride pollution in industrial facilities are discussed. Methods for collecting dust deposited on the structure and sampling concrete for chloride concentration testing are presented in detail. The test methods used and the apparatus used to assess the chloride content at the thickness of concrete reinforcement lagging are presented. Investigations of the chloride content in the concrete of the reinforcement cover showed a very high concentration of chloride in the near-surface layer, depending on the location of the element in relation to the source of chloride emission into the environment. In contrast, the concrete of the deeper layers of the lagging contained very small amounts of Cl− chlorides. The results of the chloride content of the lagging concrete were plotted against the distance from the surface of the specimen and approximated by the function C(x,t) based on Fick's second law and its solution. A satisfactory fit of the course of this function to the experimental results was obtained. Based on the obtained C(x,t) function, the durability of the main structural components of an aluminium foundry industrial hall operating in a chloride environment was estimated. [ABSTRACT FROM AUTHOR]

Based on the engineering background of the wide-width single cable-stayed bridge, the shear lag effects of the cross-section of these bridge box girders under the action of the eccentric load were experimentally studied. The behavior of shear lag effects in the horizontal and longitudinal bridge directions under eccentric load in the operational stage of a single cable-stayed bridge was analyzed by a model testing method and a finite element (FE) analytical method. The results showed that the plane stress calculation under unidirectional live load was similar to the results from spatial FE analysis and structural calculations performed according to the effective flange width described in the design specification. At the position of the main beam near the cable force point of action, the positive stress at its upper wing edge was greatest. At a distance from the cable tension point, the maximum positive stress position trend showed that from the center of the top flange to the junction of the top flange and the middle web to the junction of the top flange and the middle web and the side web. Under eccentric load, the positive and negative shear lag effects on the end fulcrum existed at the same time, and the shear lag coefficient on the web plate was larger than the shear lag coefficient on the unforced side. Due to the influence of constraint at the middle fulcrum near the middle pivot point, positive and negative shear lag effects were significant, and the coefficient variation range was large, resulting in large tensile stress on the roof plate in this area. According to FE analytical results, stress and shear forces of a single box three-chamber box girder under eccentric load were theoretically analyzed, the bending load decomposed into the accumulation of bending moment and axial force, using the bar simulation method, and the overall shear lag effect coefficient λ was obtained and verified. [ABSTRACT FROM AUTHOR]

Long‐term deformations of concrete structures are actually calculated by creep models using the mean stress level and the time‐average ambient humidity. However, temporally varying mechanical and hygric exposures which occur in practice are suspected to increase the time‐dependent strains. Nevertheless, these influences have not been sufficiently investigated so far. Therefore, the influences of cyclic‐mechanical and ‐hygric loadings, respectively, as well as their coupled influence on the long‐term deformations of concrete are systematically investigated within the scope of a joint research project funded by the German Research Foundation (DFG). In this paper, time‐dependent strains due to cyclic‐mechanical and/or ‐hygric loading of a normal strength concrete are presented in comparison to those at corresponding constant loading. The results demonstrate that the time‐dependent strains are significantly increased due to cyclic‐mechanical and ‐hygric loading compared to those due to the corresponding constant mean loading. This indicates an underestimation of strains by using the constant mean loading in creep models and may cause severe safety risks in prestressed concrete constructions. Therefore, existing models should be modified considering the influences of cyclic exposures. [ABSTRACT FROM AUTHOR]

High‐performance fibre reinforced concrete represents a promising alternative to conventional reinforced concrete for the construction of prestressed precast girders for road bridges. Specifically, all shear reinforcement is replaced by the use of steel fibres, which leads to important savings from the material and economical perspectives. Therefore, reliable shear formulations are required for these specific cases. In an effort to evaluate the accuracy of code expressions, this paper presents a database collecting 80 experimental shear tests on prestressed fibre reinforced concrete beams without stirrups. After illustrating its main characteristics, this database is used to verify the conservativeness and accuracy of shear formulation according to several codes and recommendations: i) Model Code 2010, ii) draft version of Model Code 2020, iii) draft version of the new Eurocode 2, and iv) Spanish National Code. The evaluation, carried out through the calculation of the model safety factor, indicated that the application of all shear formulations is largely conservative, leading to less unsafe tests than the desired 5% fractile. The relation between model safety factors and mechanical parameters is then investigated. Finally, the results obtained for the developed database are compared with those achieved from two larger databases of beams with similar features but without prestress. The comparison clearly proves the greater conservatism of code expressions when beams are prestressed. [ABSTRACT FROM AUTHOR]

Long‐term crack monitoring of prestressed concrete structures by means of distributed fiber‐optic strain sensing In the ceiling area of a connecting subway tunnel in Munich, Germany, fiber‐optic sensor cables were installed for continuous long‐term crack monitoring. According to the measurement concept, continuous monitoring of the total deformations as well as several reference date measurements are planned with regard to the actual crack monitoring of the prestressed concrete construction. The aim of the measurements is the fiber‐optic crack monitoring of a pre‐damaged prestressed concrete structure from the 1970s, which was refurbished in the course of the fiber‐optic installation. The structure is exposed to high traffic loads from road traffic as well as temperature impact. The prestressed concrete structure is a single span slab construction with straight and parabolic tendons. The original ceiling had an increased potential for damage on the underside of the slab (crack pattern) as well as severe damages associated with the existing prestressing steel structure. During the renovation of the prestressed concrete slab, shotcrete with supplementary reinforcement was applied to achieve an announcement behavior in case of tendon failure. The following paper reports on the first results of crack monitoring based on continuous fiber optic measurements along the embedded fiber‐optic sensing cables. The measurements are based on the technology of distributed Brillouin sensing. [ABSTRACT FROM AUTHOR]

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Accurate prediction of the prestressed steel amount is essential for a concrete-road bridge's successful design, construction, and long-term performance. Predicting the amount of steel required can help optimize the design and construction process, and also help project managers and engineers estimate the overall cost of the project more accurately. The prediction model was developed using data from 74 constructed bridges along Serbia's Corridor X. The study examined operationally applicable models that do not require indepth modeling expertise to be used in practice. Neural networks (NN) models based on regression trees (RT) and genetic programming (GP) models were analyzed. In this work, for the first time, the method of multicriteria compromise ranking was applied to find the optimal model for the prediction of prestressed steel in prestressed concrete bridges. The optival model based on GP was determined using the VIKOR method of multicriteria optimization; the accuracy of which is expressed through the MAPE criterion is 9.16%. A significant average share of 46.11% of the costs related to steelworks, in relation to the total costs, indicates that the model developed in the paper can also be used for the implicit estimation of construction costs. [ABSTRACT FROM AUTHOR]

The Italian road network comprises many bridges that were constructed around the middle of last century and are now close to, or have exceeded, their intended design lives. The advanced state of degradation of many of the bridges has been a contributing factor in a number of collapses in recent years, with the problem being particularly prevalent in prestressed concrete construction. In response to the need for improvements in the reliability of existing Italian bridges, the Ministry of Transport and Infrastructure published in 2020 a new set of guidelines for assessment and monitoring. This article undertakes a critical review of the guidelines, which are currently in a trial phase, through the multilevel assessment of a case‐study prestressed concrete road bridge. Four key areas for potential improvement in future revisions are identified: refinement of the level 3 preliminary assessment approach, greater emphasis on assessment rather than design thinking, objective Knowledge Levels, and treatment of elements with unknown levels of degradation. [ABSTRACT FROM AUTHOR]

Effects of torsional stiffness on the load‐bearing behaviour of concrete bridges with T‐beam cross section For a sustainable design of reinforced and prestressed concrete bridges in the ultimate limit state and serviceability limit state, a realistic estimation of the torsional stiffness as a function of the load level is necessary. Due to the current limited number of studies, normative bases for the recalculation of bridge structures are only available to a limited extent and are not intended for the design of new bridge constructions. The present article gives an overview of the torsional load‐bearing behavior and, in particular, the torsional stiffness of reinforced and prestressed concrete structures with T‐beam cross sections. The focus is on the redistribution of internal forces in the overall system associated with the reduction of torsional stiffness, which leads, among other things, to lower design torsional moments and consequently to a smaller amount of reinforcement required for torsional loading. This is explained clearly using a parameter study with the Bieger model and the example of a bridge recalculation as well as the design of a new bridge in prestressed concrete construction. [ABSTRACT FROM AUTHOR]

Prestressed concrete box girders with web tendons and unbonded transverse prestressing With the introduction of regulations and guidelines for the design of civil engineering structures (BEM‐Ing) especially for the calculation and design of concrete bridges (part 1, section 2), road bridge construction using prestressed concrete will change. For the first time since 1999 the arrangement of internal tendons in webs of box girders, it is permitted again. However, in order to avoid the shortcomings observed in some road bridges, which result, among other things, from a insufficient compaction of the concrete in the webs, stricter boundary conditions for the use of the bridge tendons in road bridge construction will be anchored in the future, while their possible applications in railway bridge construction will remain unchanged. In addition, it is strongly recommended to design road slabs of large width with transverse prestressing. For the deflection limitation of transversely prestressed road slabs, the maximum prestress force is limited in BEM‐Ing, which can be used to determine the required plate thickness by controlling of the concrete tension stresses. This article provides hints on the design and construction of prestressed concrete box bridges according to the new BEM‐Ing and shows which component dimensions result from the new rules. [ABSTRACT FROM AUTHOR]

Steel in bridge constructions is often associated with very large span bridges due to its favorable relationship between strength and weight. But even for bridges with small and medium spans of up to 60 m, steel combined with concrete as a composite bridge can lead to economically justifiable constructions, especially when the performance during the complete life‐cycle is integrated. In this paper, two life‐cycle oriented calculation methods (life‐cycle costs and external costs) are introduced and applied. As a result, comparisons between two abutment solutions (conventional reinforced concrete abutment and a permanent steel sheet pile abutment) and two superstructure variants (steel composite construction and in‐situ prestressed concrete superstructure) are presented. It is shown that accelerated construction processes, durable materials, and a smart bridge‐design considering actual technological developments lead to economically advantageous solution for traffic infrastructures. [ABSTRACT FROM AUTHOR]

Until 2016, the in situ, span-by-span, prestressed concrete deck construction of multi-span bridges was limited to spans up to 78 m. This construction method, in some cases, ensures verifiable advantages in terms of construction simplicity and reduction in material consumption. After scientific and technical validation of the organic prestressing technology application in movable scaffolding systems in 2005, and evaluation of its potential features, a long-term multidisciplinary research and development project was developed to evaluate the possibility of using this technology for in situ construction of multi-span decks with spans up to 90 m. In 2018, in Turkey, the first viaduct using this technology anywhere in the world was completed. In the present paper, following a presentation of prior scientific and technological achievements, the main technical data of this case study are given, highlighting its results. This technological achievement is a contribution to the state of the art of bridge engineering and to sustainability. [ABSTRACT FROM AUTHOR]

Modified asphalt binders and mixtures are the most important construction materials for pavement, and therefore they always attract research interest all over the world. In this Special Issue, J.-C. Carret, H. Di Benedetto, and C. Sauzéat characterized asphalt mixes' behavior from dynamic tests and made a comparison with conventional cyclic tension-compression tests [[2]]. 10.3390/app8091475 7 Ahmad N., Nasir M.A., Hafeez M., Rafi J., Zaidi S.B.A., Haroon W. Carbon Nanotubes (CNTs) in Asphalt Binder: Homogeneous Dispersion and Performance Enhancement. [Extracted from the article]

The roof of the Schwarzwaldhalle in Karlsruhe – Examination of an anticlastic curved roof‐shell from the 1950s The roof of the Schwarzwaldhalle is an anticlastic curved roof shell from the 1950s. The roof‐shell was built in a pre‐stressed concrete construction and was the first hall in Europe with a parabolic suspended roof made of pre‐stressed concrete with a thickness of only around 6 cm. The roof was a symbol of his time. The architecture was looking for new forms to express the feeling of life in post‐war Germany. For example, the architect Prof. Erich Schelling together with the structural engineer Ulrich Finsterwalder designed a building that was bold at the time. Not least because of the roof, the hall was internationally recognized. In 2008 an extensive renovation of the roof‐shell cover, the roof was also supplemented by an extensive monitoring concept for condition monitoring. To this end a measuring system with several strain gauges (DMS) and temperature sensors on the roof was installed. The measurements are supplemented by FE‐calculations, visual and annual assessments taking into account all the data collected. [ABSTRACT FROM AUTHOR]

This paper experimentally analyzes the working behavior characteristics of a large-curvature continuous pre-stressed concrete box-girder (CPCBG) bridge model based on structural stressing state theory. First, the measured strain data is modeled as generalized strain energy density (GSED) to characterize the stressing state of the bridge model. Then, the Mann-Kendall (M-K) criterion is adopted to detect the stressing state leaps of the bridge model according to the natural law from quantitative change to qualitative change of a system, which derives the new definition of structural failure load. Correspondingly, the stressing state modes for the bridge model's sections and internal forces are proposed to verify their changing characteristics and the coordinate working behavior around the characteristic loads. The analytical results reveal the working behavior characteristics of the bridge mode unseen in traditional structural analysis, which provides a new angle of view to conduct structural analysis and a reference to the improvement of design codes. [ABSTRACT FROM AUTHOR]

Highlights • 3D FEMs have been developed and rigorously validated. • Full-scale tests prestressed concrete sleepers with holes and web openings are conducted. • It is the word first to identify damages and failure modes of the sleepers with holes and web openings. • Novel insights into the behaviours of the sleepers with holes and web openings exposed to impact loading are highlighted. • Two advanced material modelling techniques are exercised and benchmarked. • Brittle cracking model provides better damage predictions than Damage Plasticity Model. • Holes and web openings induce shear failure of the sleepers under impact loading. Abstract Prestressed concrete sleepers are essential to the structural integrity of railway track structures, redistributing wheel loads from the rails to underlying ballast bed while securing rail gauges for safe train traffics. In practice, drilled holes or web openings are usually generated ad hoc in sleepers to enable signalling equipment and cables at a construction site. These holes and web openings could however affect the structural integrity of sleepers, especially when they are exposed to impact loading. In fact, statistically, 15–25% of dynamic loading conditions are of transience and high-intensity by the nature of wheel-rail interaction over irregularities. This study is thus the world first to rigorously investigate the impact behaviours of railway sleepers with hole and web openings, which is critical to railway safety and reliability. In this study, three-dimensional finite element modelling using ABAQUS Explicit is used to comprehensively design and analyse the behaviour of prestressed concrete sleepers with various types of holes and web openings upon impact loading. Two different modelling techniques including concrete damaged plasticity model and brittle cracking model are also exercised to aid in this study. The results obtained show that the brittle cracking model provides better damage results as it can illustrate crack propagation very well until reaching the failure mode under impact loading. The findings illustrate a pathway to use brittle cracking model instead of concrete damaged plasticity model for dynamic impact analysis. Moreover, the outcome of this study will provide a better and new insight into the influences of holes and web openings on sleepers' failure modes under impact loading so that appropriate guidance can be proposed to rail and track engineers in order to generate holes and web openings ad hoc in prestressed concrete sleepers without compromising their structural performance. [ABSTRACT FROM AUTHOR]

In this study, a new mixture design methodology based on the 4-parameters compressible packing model (CPM) of Packing Density Theory was proposed to satisfy the specific performance criteria of high performance concrete for prestressed concrete bridge construction. Iterative algorithms were developed to determine the parameter of critical cavity size ratio x 0 which reflect the crushed aggregate particles shape property and optimize the proportions of aggregates with different size range. After the optimization of aggregates, all the components in concrete were calculated. Thirty-one concrete mixtures with coarse aggregate from 5 different sources have been formulated according to this method to validate it both in fresh and hardened state. The workability, mechanical, and durability properties are verified during the slump, compressive strength, shrinkage, chloride-penetration resistance, and freeze-thaw resistance tests to characterize the obtained high-performance concrete. It is clear from the study that the proposed method is a successful theory for optimizing composition of high performance concrete. [ABSTRACT FROM AUTHOR]

An extensive experimental and theoretical research study was undertaken to study the vibration serviceability of a long-span prestressed concrete floor system to be used in the lounge of a major airport. Specifically, jumping impact tests were carried out to obtain the floor’s modal parameters, followed by an analysis of the distribution of peak accelerations. Running tests were also performed to capture the acceleration responses. The prestressed concrete floor was found to have a low fundamental natural frequency (≈ 8.86 Hz) corresponding to the average modal damping ratio of ≈ 2.17%. A coefficients βrp is proposed for convenient calculation of the maximum root-mean-square acceleration for running. In the theoretical analysis, the prestressed concrete floor under running excitation is treated as a two-span continuous anisotropic rectangular plate with simply-supported edges. The calculated analytical results (natural frequencies and root-mean-square acceleration) agree well with the experimental ones. The analytical approach is thus validated. [ABSTRACT FROM AUTHOR]

The presence of a conductive layers of hot-formed oxide on the surface of bars for pre or post-compressing structures can promote localized attacks as a function of pH. The aggressive local environment in the occluded cells inside localized attacks has as consequence the possibility of initiation of stress corrosion cracking. In this paper, the stress corrosion cracking behavior of high strength steels proposed for tendons was studied by means of Constant Load (CL) tests and Slow Strain Rate (SSR) tests. Critical ranges of pH for cracking were verified. The promoting role of localized attack was confirmed. Further, electrochemical tests were performed on bars in as received surface conditions, in order to evaluate pitting initiation. The adverse effect of mill scale was recognized. [ABSTRACT FROM AUTHOR]

Based on realistic modeling of 44 bridges in national bridge inventory using its actual layout and dimensions, a theoretical framework is defined to calculate the tolerable differential settlement limits based on the over-bending moment or over-shear force generated by settlements and the moment or shear capacity of the bridge. First, the derived over-bending moment or over-shear force is validated through literature results. Second, the differential settlement limits of bridges are derived from the bridge strength capacities. Finally, based on the established differential settlement limits, the relationship of bridge differential settlement limits with its span length, number of spans, bridge skew, and the bridge type is discussed and compared with American Association of State Highway and Transportation Officials specification (2010). A statistics-based differential settlement limit criterion is also suggested for steel and pre-stressed concrete bridges and compared with the field survey results. From the research outcomes, it is concluded that extra caution is needed when implementing the 0.4% differential settlement limits of bridge foundations in American Association of State Highway and Transportation Officials. [ABSTRACT FROM AUTHOR]

This paper experimentally studied the strengths of the steel strand and strand-concrete (or cement slurry) bond stress under different cryogenic temperatures ranging from 20 to -160 °C. Twenty one tensile tests were firstly carried out to obtain the yield and ultimate strengths of the steel strand under different cryogenic temperatures. The influences of the cryogenic temperatures on the yield strength, ultimate strength, and fracture strain of the steel strand were discussed and analyzed. Sixty six pull-out tests with 3 identical specimens for each parameter were carried out to obtain the ultimate strength behaviors of the strand-concrete (or cement slurry) bond. The failure modes, strand-concrete (or cement slurry) bond stress, and influences of the low temperature and strength of concrete on the bond stress were reported, discussed, and analyzed. Design equations were also developed to predict the yield and ultimate strengths of the steel strand under temperature intervals of 20 to -160 °C, and their accuracies were checked through validations against the test results. Prediction models in the literature were also used to predict the strand-concrete bond stress, and their accuracies were checked by the reported test results. Empirical design equations were also developed to predict the strand-cement slurry bond stress at cryogenic temperatures. [ABSTRACT FROM AUTHOR]

Corrosion of anchorage head system may lead to severe structural failure. To understand the characteristics of corrosion and the risks of anchoring failure, 11 post-tensioned prestressed concrete specimens with single-hole anchorage-plate system sealed with postcast concrete contaminated by NaCl were fabricated and then corroded for 8 months. By periodically monitoring corrosion current density and breaking the specimens to detect mass loss, the time-varying law of corrosion rate and the influences of chloride concentration and cover layer depth on corrosion rate were found. The mean corrosion rate of each component of anchorage head system varies with effective prestress level in a light growing trend with approximate linear relationship. The plates were corroded most severely and manifested relatively full and uniform corrosion characteristics, whereas the barrels and wedges were corroded slightly and exhibited relatively local and pitting corrosion characteristics. The average corrosion rate of the plates is 50 times and 80 times higher than that of the barrels and wedges, respectively. The interfaces of the contacted components were hardly corroded. Finally, the corrosion risk of the anchorage head system was analyzed. [ABSTRACT FROM AUTHOR]

This paper presents probabilistic analysis of structural capacity of pre-stressed concrete containments subjected to internal pressure. The conventional design methods for containments are based on allowable stress codes which ensure certain factor of safety between expected load and expected structural strength. Such an approach may give different values of structural reliability in different situations. In recent years, two international round robin exercises have been conducted aimed at predicting the capacity of lined and unlined pre-stressed concrete containments used in nuclear industry. These exercises involved experimental testing and numerical analysis of the models. The first exercise involved 1/4 scale steel-lined Pre-stressed Concrete Containment Vessel (PCCV) which was tested at Sandia National Laboratories (SNL) in USA. The second used an unlined containment being tested by the Bhabha Atomic Research Centre (BARC), Tarapur, India. These studies are essentially deterministic studies that have helped validate the analysis methodology and modelling techniques that can be used to predict pre-stressed concrete containment capacity and failure modes. The paper uses these two examples to apply structural reliability method to estimate the probability of failure of the containment. The two international round robin exercises have already established the ultimate structural collapse mode of the containments under internal pressure loading which indicate that the failure takes place in the general field of the containment wall around mid-height and away from any major structural discontinuities like the penetrations. This is because robust design procedures have been used to avoid structural failure at discontinuities by providing adequate compensation. Based on these experimental studies and the attendant numerical analyses a failure function is presented that assumes first yielding in the hoop direction at mid-height of the cylinder wall. A failure function equating the free-field membrane hoop stress to the hoop strength as a function of cross-sectional area (per unit height) and yield stresses of concrete, rebar, liner plate and tendons is developed. First Order Reliability Method (FORM) is applied to predict probability of failure of the containments. Probability of failure vs internal pressure is presented for both types of containments. The paper presents a simple method to establish structural reliability of a pre-stressed concrete containment which can be useful for probabilistic safety assessment when considering extreme events that lead to over-pressurisation of the containment. The FORM approach was validated by comparison to the results of analogous calculations using Subset Simulation and Importance Sampling techniques for Monte Carlo simulation. It was found that at high pressures the Advanced FORM approach yields a good approximation to the true probability of failure. The sensitivity of the probability of failure to the assumed coefficients of variation of properties of the containment was studied using the Sobol and Total Sensitivity Indices. At design pressure it was found that the coefficients of variation of the tendon yield and tendon area are the most important parameters followed by the applied pressure and containment radius. At higher pressures it was found that the coefficients of variation of the applied pressure and containment radius are the most important parameters. The variability of the probability of failure is decreased at higher pressures, but the coefficients of variation still play an important role. [ABSTRACT FROM AUTHOR]

This paper describes a study of the Tempul Aqueduct, one of the first structures designed and built by Eduardo Torroja. At a time when computers did not exist, Torroja’s courage and innovation were outstanding. He was in no way constrained by a lack of theoretical knowledge, inadequate materials and the contemporary doubts about cable-stayed structures. In fact, he was able to build one of the world’s first prestressed concrete structures, and a precursor to modern cable-stayed and extradosed bridges. This paper briefly reviews the history of the Tempul Aqueduct, gives the results of the analysis of this structure by several Finite Element Models (FEMs), and compares the FEM results to those obtained by Torroja himself. The FEM results confirm the validity of Torroja’s conceptual design. The paper also contains a detailed analysis of the influence of the structural system on the behavior of the bridge and the effect of removing the live loads with the aim of providing a better understanding of the context and behavior of the Tempul aqueduct. [ABSTRACT FROM AUTHOR]

Minimum radii of curvature of internal bonded tendons Due to the introduction of EAD 160004 as new basis for issuing European Technical Assessments concerning post-tensioning systems for prestressing of structures, minimum radii of curvature for deviation of internal bonded tendons have been defined on the European level for the first time. This definition differs significantly from the minimum radii of curvature permitted in Germany so far. In addition to explain some of the background, the paper shows a relationship between the existing and the new minimum radii by means of a differentiating comparison. Using a suitable value of the allowable transverse pressure under the most loaded prestressing strand, it is possible to convert the previous radii into the new format on the basis of an explicit acceptance criterion. If the limiting value for the radius of curvature of 2.50 m is observed, the bending stress due to deviation of the prestressing strand is not decisive. [ABSTRACT FROM AUTHOR]

Torsion structural behavior of external prestressed circular segments with dry joints In the tower construction of wind power plants concrete or hybrid towers are established, especially for high towers, they have replaced the traditional steel towers due to better transportability. The needed joints for the prefabricated construction method leads to problems, which are not satisfactorily resolved by the current models and calculation approaches. In the case of the formation of dry joints (horizontal joints) between the segments, the force transmission of the lateral forces and torsion moments take place exclusively through the friction in the joint, the external prestressing and the coefficient of friction generate the frictional resistance. The capacity of lateral force between the joints should be calculate by a linear calculation approach, that the permissible transverse force corresponds to the prestressing force multiplied by the coefficient of friction. For the transmission of the torsional moments, the calculation is carried out according to the known torsion theories of Bredt and Saint-Venant, as long as the joints are overpressed, they can transmit a very high torsional moment. However, in the ultimate limit state, if the joint begin to open, the permissible torsional moment drops immediately to a very small value and thus becoming a critical criterion for the tower. According to recent investigations, these approaches witch describe the bearing and deformation behavior of such a joints are incorrect, results in an uncertainty range and a very large unused potential. [ABSTRACT FROM AUTHOR]

In recent years, numerous explosion and collision related tragedies due to military attack, terrorist bombing, and vehicle accident have occurred all over the world. However, researches on Prestressed Concrete (PSC) infrastructures such as Prestressed Concrete Containment Vessels (PCCVs) and LNG storage tanks under extreme loading such as impact, blast, and fire loading scenario are not being studied sufficiently. Especially, researches on possible secondary fire after bomb explosion or accidental collision on concrete structures has not been performed, while most of the past researches related to extreme loadings on structures focused on ideal isolated extreme loading event researches. Therefore, in this study, the PSC panel such as wall of PCCV and LNG storage tank is analytically evaluated under impact-blast-fire combined loading scenarios. For the analytical simulations of impact/blast and fire loaded behavior of the PSC panel, commercial finite element analysis program of LS-DYNA and MIDAS FEA, respectively, were used. Then, a simulation procedure coupling LS-DYNA and MIDAS FEA using element elimination algorithm is proposed to couple explicit and implicit finite element analyses (FEA) to perform structural analysis of impact or blast induced fire loading scenario. Then, the simulation results from the PSC and RC specimens applied with impact induced fire or blast induced fire loadings were compared with those of undamaged PSC and RC specimens. The results showed that PSC panel was more severely damaged from the fire due to the confining effect of prestressing forces. Confining effect increased the thermal conductivity of concrete due to compaction of concrete. Also, the spalling of concrete caused by impact loading followed by fire loading were implemented to the simulation model using the element elimination procedure proposed in the study. The simulation results obtained from the proposed simulation procedure agree well with the impact induced fire test results. [ABSTRACT FROM AUTHOR]