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In the freeze-thaw zone, the pre-stressed concrete of bridge structure will be damaged by freezing-thawing, the bearing capacity of structure will decrease and the safety will be affected. The purpose of this paper is to establish the time-dependent resistance degradation model of structure in the freeze-thaw zone, and analysis the structural reliability and remaining service life in different freeze-thaw zones.

First, according to the theory of structural design, a calculation model of the resistance of pre-stressed concrete structures in f freeze-thaw zone is established. Second, the time-dependent resistance model was verified by the test beam bending failure test results done by the research group, which has been in service for 20 years in freeze-thaw zone. Third, using JC algorithm in MATLAB to calculate the index on the reliability of pre-stressed concrete structure in frozen thawed zones, forecasting the s remaining service life of structure.

First, the calculation model of the resistance of pre-stressed concrete structures in freeze-thaw zone is accurate and it has excellent applicability. Second, the structural resistance deterioration time in Wet-Warm-Frozen Zone is the earliest. Third, once the pre-stressed reinforcement rusts, the structural reliability index will reach limit value quickly. Finally, the remaining service life of structure meets the designed expectation value only in a few of freeze-thaw zones in China.

The research will provide a reference for the design on the durability of a pre-stressed concrete structure in the freeze-thaw zone. In order to verify the security of pre-stressed concrete structures in the freeze-thaw zone, engineers can use the model presented in this paper for durability checking, it has an important significance.

During service period, due to the overload or other non-load factors, cracks of the pre-stressed concrete beam are seriously affecting the safety of the bridge structure. The purpose of this paper is to quickly realize the bearing capacity and the loss of the section stiffness through fracture characteristics and make correct judgments.

Through the flexural failure test of two test beams: collecting data of fracture characteristics and section stiffness loss value. According to the fracture characteristic data, the flexural stiffness of the section is obtained by the nonlinear calculation method, and the results are verified by test data. Data regression method is used to establish the section flexural stiffness loss ratio calculation formula, nominal tensile strain at the bottom edge of the cross-section used as a variable factor, and the accuracy of this formula is verified by comparing the flexural failure test results of pre-stressed hollow plates.

The loss of the flexural stiffness of section shows the decrease trend of first-fast-then-slow and the structural stiffness is sensitive to the initial cracking of beam. The calculation formula on the loss ratio of the flexural stiffness of section established with the nominal tensile stress at the bottom edge of beam as a variable is accurate and feasible, it realizes the possibility of assessing the stiffness loss of pre-stressed concrete structure by adopting the statistic parameters on crack characteristics.

A method for quickly determine the stiffness loss of structures by using fracture characteristics is established, and using this method, engineers can quickly determine whether a bridge is a dangerous bridge, without loading test. So, this method not only ensures the safety of human life, but also saves money.

During service period, due to the overload or other non-load factors, diagonal cracks of the pre-stressed concrete beam are seriously affecting the safety of the bridge structure. The purpose of this paper is to quickly realize the shear bearing capacity and shear stiffness through maximum width of the diagonal cracks and make correct judgments.

Through the shear failure test of four test beams, collecting data of diagonal cracks and shear stiffness loss value. According to the deformation curve of the shear stiffness, and combined with the calculation formula of the maximum width of diagonal cracks, the formula for calculating the effective shear stiffness based on the maximum width of diagonal cracks is deduced, then the results are verified by test data. Data regression method is used to establish the effective shear stiffness loss ratio calculation formula, the maximum width of diagonal cracks used as a variable factor, and the accuracy of this formula is verified by comparing the shear failure test results of pre-stressed hollow plates.

With the increase in width of the diagonal crack, the loss rate of shear stiffness of the concrete beams is initially fast and then becomes slow. The calculation formulae for shear stiffness based on the maximum width of the diagonal cracks were deduced, and the feasibility and accuracy of the formulae were verified by analysis and calculation of shear test data.

A method for quickly determine the shear stiffness loss of structures by using maximum width of the diagonal cracks is established, and using this method, engineers can quickly determine effective shear stiffness loss ratio, without complex calculations. So this method not only ensures the safety of human life, but also saves money.

The Government’s investment in infrastructure projects is considerably high, especially in bridge construction projects. Government authorities must establish an initial forecasted budget to have transparency in transactions. Early cost estimating is challenging for Quantity Surveyors due to incomplete project details at the initial stage and the unavailability of standard cost estimating techniques for bridge projects. To mitigate the difficulties in the traditional preliminary cost estimating methods, there is a requirement to develop a new initial cost estimating model which is accurate, user friendly and straightforward. The research was carried out in Sri Lanka, and this paper aims to develop the artificial neural network (ANN) model for an early cost estimate of concrete bridge systems.

The construction cost data of 30 concrete bridge projects which are in Sri Lanka constructed within the past ten years were trained and tested to develop an ANN cost model. Backpropagation technique was used to identify the number of hidden layers, iteration and momentum for optimum neural network architectures.

An ANN cost model was developed, furnishing the best result since it succeeded with around 90% validation accuracy. It created a cost estimation model for the public sector as an accurate, heuristic, flexible and efficient technique.

The research contributes to the current body of knowledge by providing the most accurate early-stage cost estimate for the concrete bridge systems in Sri Lanka. In addition, the research findings would be helpful for stakeholders and policymakers to propose policy recommendations that positively influence the prediction of the most accurate cost estimate for concrete bridge construction projects in Sri Lanka and other developing countries.

This paper reviews the techniques available for assessing the material characteristics and long‐term performance of high alumina cement concrete construction. The use of some of these techniques is illustrated in a case study on typical pre‐cast concrete beams.

In order to establish sustainable development, there is a need to focus on solutions effectively improving environmental performance. Effectiveness is the product of significance and improvement potential. For buildings, the supporting structure is the predominant environmental load by materials, hence significant. The purpose of the studies presented in this paper is to determine the improvement potential of the supporting structure of buildings and explore other sustainable solutions effectively enhancing environmental performance.

For the same office layout, various combinations of structural components at different spans were studied. The environmental load of these variants was determined by means of an life cycle analysis (LCA)‐based model.

The studies presented in the paper demonstrated an environmental difference by a factor of 5 between the solutions performing worst and best. The optimal combination is the uncommon solution of TT‐slabs with timber beams and columns, expecting to establish an improvement factor of 4 with respect to common practice.

The findings of the studies presented suggest another way of building, with common structural components but whose combination is not common at present.

So far, sustainable building has not focused enough on effective solutions and has had little means to do so. Approaching the supporting structure of buildings rather than small, ineffective adaptations will significantly improve environmental building performance. An elaborate LCA of supporting structures had never been done before. The paper, on the one hand, rationalises sustainable building and, on the other hand, supports effective sustainable design.

This study aims to present comprehensive nonlinear material modelling techniques and simulations of reinforced concrete (RC) beams subjected to short-term monotonic static load using the robust and reliable general-purpose finite element (FE) software ANSYS. A parametric study is carried out to analyse the flexural and ductility behaviour of RC beams under various influencing parameters.

To develop and validate the numerical FE models, a total of four experimentally tested simply supported RC beams are taken from the available literature and two beams are selected from each author. The concrete, steel reinforcements, bond-slip mechanism, loading and supporting plates are modelled using SOLID65, LINK180, COMBIN39 and SOLID185 elements, respectively. The validated models are then used to conduct parametric FE analysis to investigate the effect of concrete compressive strength, percentage of tensile reinforcement, compression reinforcement ratio, transverse shear reinforcement, bond-slip mechanism, concrete compressive stress-strain constitutive models, beam symmetry and varying overall depth of beam on the ultimate load-carrying capacity and ductility behaviour of RC beams.

The developed three-dimensional FE models can able to capture the load and midspan deflections at critical points, the accurate yield point of steel reinforcements, the formation of initial and progressive concrete crack patterns and the complete load-deflection curves of RC beams up to ultimate failure. From the numerical results, it can be concluded that the FE model considering the bond-slip effect with Thorenfeldt’s concrete compressive stress-strain model exhibits a better correlation with the experimental data.

The ultimate load and deflection results of validated FE models show a maximum deviation of less than 10% and 15%, respectively, as compared to the experimental results. The developed model is also capable of capturing concrete failure modes accurately. Overall, the FE analysis results were found quite acceptable and compared well with the experimental data at all loading stages. It is suggested that the proposed FE model is a practical and reliable tool for analyzing the flexural behaviour of RC members and can be used for performing parametric studies.

This paper aims to investigate the state of the art for the reliability evaluation of reinforced concrete beams in a fire situation. Special emphasis is placed on addressing which parameters were considered probabilistically or deterministically, the prescribed probabilistic models for the assumed stochastic variables, the treatment of the heat transfer mechanism, the quantification of the structural fire performance and the assumed target reliability levels.

Research papers were identified through a search on the Web of Science, Google Scholar and detailed searches within the journals Journal of Structural Fire Engineering, Fire Technology and Fire Safety Journal, supplemented with references known by the authors.

Considering the state-of-the-art review, gaps in the literature are identified related to (1) the probabilistic evaluation of shear capacity for standard fires and parametric fires, and bending capacity for parametric fires, (2) the absence of reference fragility curves for immediate design application/code calibration and (3) the specification of target safety levels for reliability-based design.

The lack of research papers gathering studies on the reliability of reinforced concrete beams in fire situation makes it difficult to further develop research in the area. The value of this work lies precisely in the collection of the basic information, making it possible to identify gaps to be addressed in future research and the suggestion of a research framework.

During service, cracks are caused in prestressed concrete beams owing to overload or other non-load factors. These cracks significantly affect the safety of bridge structures. The purpose of this paper is to carry out a non-linear iterative calculation for a section of a prestressed concrete beam and obtain the change in stiffness after the section cracks.

The existing stress of prestressed reinforcement was measured by performing a boring stress release test on two pieces of an in-service 16 m prestressed concrete hollow plate. Considering the non-linear effects of materials, the calculation model of the loss in the flexural stiffness of the prestressed concrete beam was established based on the existing prestress. The accuracy of the non-linear calculation method and the results obtained for the section were verified by conducting a bending destruction test on two pieces of the 16 m prestressed concrete hollow plate in the same batch and by utilising the measured strain and displacement data on the concrete at the top edge of the midspan section under all load levels.

The flexural stiffness of the section decreases rapidly at first and then gradually, and structural rigidity is sensitive to the initial cracking of the beam. The method for calculating the loss in the flexural stiffness of the section established with the existing stress of prestressed reinforcement as a parameter is accurate and feasible. It realizes the possibility of assessing the loss in the rigidity of a prestressed concrete structure by adopting the existing stress of prestressed reinforcement as a parameter.

A method for quickly determining the loss in the stiffness of structures using existing prestress is established. By employing this method, engineers can rapidly determine whether a bridge is dangerous or not without performing a loading test. Thus, this method not only ensures the safety of human life, but also reduces the cost of testing.

The partially prestressed concrete beam with unbonded tendon is still an active field of research because of the difficulty in analyzing and understanding its behavior. The finite-element (FE) simulation of such beams using numerical software is very scarce in the literature and therefore this study is taken to demonstrate the modeling aspects of unbonded partially prestressed concrete (UPPSC) beams. This study aims to present the three-dimensional (3-D) nonlinear FE simulations of UPPSC beams subjected to monotonic static loadings using the numerical analysis package ANSYS.

The sensitivity study is carried out with three different mesh densities to obtain the optimum elements that reflect on the load–deflection behavior of numerical models, and the model with optimum element density is used further to model all the UPPSC beams in this study. Three half-symmetry FE model is constructed in ANSYS parametric design language domain with proper boundary conditions at the symmetry plane and support to achieve the same response as that of the full-scale experimental beam available in the literature. The linear and nonlinear material behavior of prestressing tendon and conventional steel reinforcements, concrete and anchorage and loading plates are modeled using link180, solid65 and solid185 elements, respectively. The Newton–Raphson iteration method is used to solve the nonlinear solution of the FE models.

The evolution of concrete cracking at critical loadings, yielding of nonprestressed steel reinforcements, stress increment in the prestressing tendon, stresses in concrete elements and the complete load–deflection behavior of the UPPSC beams are well predicted by the proposed FE model. The maximum discrepancy of ultimate moments and deflections of the validated FE models exhibit 13% and −5%, respectively, in comparison with the experimental results.

The FE analysis of UPPSC beams is done using ANSYS software, which is a versatile tool in contrast to the experimental testing to study the stress increments in the unbonded tendons and assess the complete nonlinear response of partially prestressed concrete beams. The validated numerical model and the techniques presented in this study can be readily used to explore the parametric analysis of UPPSC beams.

The developed model is capable of predicting the strength and nonlinear behavior of UPPSC beams with reasonable accuracy. The load–deflection plot captured by the FE model is corroborated with the experimental data existing in the literature and the FE results exhibit good agreement against the experimentally tested beams, which expresses the practicability of using FE analysis for the nonlinear response of UPPSC beams using ANSYS software.