Code provisions for a simplified check of the long‐term deflection of concrete structures are generally developed for predefined values of the relevant input parameters. Deflection calculation may be of interest to account for different design situations. EN 1992‐1‐1 advocates the integration of curvatures calculated using the effective modulus of concrete. This paper presents an efficient procedure for calculation of the long‐term deflection due to a sustained load. A nondimensional analysis of the mean curvature is applied to evaluate the deflection. The deflection is calculated using a set of algebraic expressions. The result is close to the value obtained by the numerical integration of curvatures. The values of relevant parameters in the expressions may be selected within the common range for the design of engineering structures. The efficiency of the deflection prediction based on the integration of curvatures is tested on the available experimental data. In the first approach, the measured material properties are used. In the second approach, the required values are derived from EN 1992‐1‐1 expressions to predict the material properties.

Different analytical methods, with different levels of approximations and accuracy, are available for analysis of continuous composite steel-concrete beams. The Eurocode 4 recommends few simple methods for calculation of creep, shrinkage, cracking of concrete and shear lag effects that are explained in the paper. Through the numerical examples of four continuous composite steel-concrete beams, the proposed methods of analyses are evaluated and compared. Practical recommendations for analysis of this type of girders are formulated

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<p>The state-of-the-art Bridge Management Systems (BMSs) feature tightly coupled deterioration and preservation optimization model that enable determining the most cost-effective maintenance strategies at both the project and network levels. In other to improve deterioration model, many authors suggest the application of Weibull distribution for the sojourn time in condition states. Consequently, one has to solve semi-Markov decision process to determine the optimum preservation policy. It can be shown that the long-run optimal policies obtained using semi- Markov model doesn’t differ from those of time homogenous Markov chains for average cost criteria if the expected sojourn times in each condition state are same for both model. However, financial needs differ between the models depending on distribution parameters of sojourn time in each condition state. It is therefore that the estimation of these parameters is crucial for the realistic estimation of the financial needs. In this paper, the semi-Markov decision process is briefly presented and recommendations regarding its practical applications in bridge management are given.</p>

Indirect deflection control usually applies the limitation of the span-to-depth ratio. The procedures that have developed in the past decades have mostly been derived for predefined values of some of the relevant parameters. Assigning values to parameters simplifies the application of criteria. Predefined values may not be suitable for all design situations and some of the recently published procedures allow direct selection of relevant parameters. This paper offers new expressions for span-to-depth ratio limits for deflection control.Expressions include cross-section size, area, and position of tensile and compressive reinforcement, mechanical and long-term properties of concrete and deflection limit. The load level is represented by the stress in the tensile reinforcement so that the ratio of live and total load can be arbitrary. The dimensionless form of deflection calculation by numerical integration of the mean curvature according to Eurocode 2 is used to formulate the expressions. The proposed procedure is verified with a large number of numerical simulations for different combinations of inputs. Measured long-term deflections, available from the literature, are also used to test the procedure. The expressions are suitable for both deflection control and conceptual design.

Research on the long-term behavior of composite concrete girders made continuous is presented in the paper. Concrete precast element is cracked under construction load. Creep and differential shrinkage of precast and in-situ cast part of the girder also induce stresses in a structure. The subject of this investigation is redistribution of section forces in course of time for concrete girders subjected to change of the structural system. The aim of investigation is to verify design models and analytical procedures by experimental research

The design of concrete members for shear without stirrups, except for the minimum required, has become a major issue worldwide. It was noticed that the shear capacity of concrete element according to the Eurocode 2 often gives significant smaller values than the one predicted by former codes. This fact brought into focus the assessment of the existing structures which were built with minimum shear reinforcement. Most of the Code provisions for shear for members without shear reinforcement are based on empirical relationships. In general, Eurocode 2 doesn't make a difference between reinforced and prestressed elements. Several clauses in EN1992-1-1 which deal with the shear design are critically reviewed in the paper.

UVODČelične cevi ispunjene betonom, to jest CFT (Concrete Filled Tubes -CFT) stubovi predstavljaju jedan od tipova spregnutih stubova. Pri opisivanju njihovog ponašanja, neophodno je imati u vidu različite nelinearne uticaje koji ih karakterišu. U ovom radu predložen je numerički model za nelinearnu analizu kvadratnih CFT stubova, baziran na primeni fiber konačnog elementa raspodeljene plastičnosti. Prema dosadašnjim istraživa-njima, ovaj konačni element pokazao se kao dosta pouzdan -kako prilikom modeliranja čeličnih i betonskih, tako i u slučaju spregnutih konstrukcija [1], [2]. Ovde su analizirani njegova primena i izbor parametara modela prilikom opisivanja nelinearnog ponašanja uzoraka izloženih delovanju statičkog opterećenja, pri različitoj vitkosti uzoraka, različitom odnosu D/t (odnos ukupne dimenzije čeličnog profila [D] i debljini čeličnog profila [t]), kao i uzoraka izloženih različitim tipovima statičkog naprezanja. Tačnost modela proverena je upoređivanjem sa eksperimentalnim podacima dostupnim u literaturi.Nikola Blagojević, mast. inž. građ.