Green roofs are considered to be one of the optimal tools for saving energy and protecting the environment in developed countries. In this paper, an analysis of the possible application of green roofs on existing residential buildings with flat roofs is presented. In the economic analysis, models of existing buildings in Belgrade, with two different types of green roofs, are studied. A key indicator of investment profitability in this investigation is the net present value (NPV) of the green roof project. Besides the private economic impact, other aspects of green roof applications, significant for sustainable development, have been highlighted. The values of the reductions in the annual energy needed for heating and cooling are compared for different scenarios. A maximum energy saving of 22% in the heating season is determined in the building energy simulation program for the model with an intensive green roof. Life cycle profit analysis was based on the probabilistic approach. The corresponding variance-based sensitivity analysis determined the impact of various parameters on the final result. In all models, the first order sensitivity index, which measures the impact of the number of residential units on the NPV, ranges from 12.2% to 63.6%. Sensitivity analysis showed that the benefit of property value increase has the highest influence on the calculated NPV in scenarios that account for this benefit. The obtained results in those scenarios indicate that the most probable NPV at the end of the life cycle is EUR 43/m² and EUR 82/m² for extensive and intensive green roofs, respectively.

This paper considers the phenomenon of the instability of steel plane frame structures in the elastic–plastic domain. The numerical analysis uses finite element method, where the corresponding stiffness matrices are based upon the trigonometric and hyperbolic interpolation functions of normal forces. The tangent modulus concept is applied when buckling occurs in the plastic range. Thus, the stiffness matrices for nonlinear material behavior are also derived. The procedure for determining effective length factors of compressed columns, which implies a global stability analysis of entire frames, is established too. It means that the proposed approach is based on the assumption that the collapse of the structure occurs when the most loaded columns reach their stability limit. So, the presented procedure enables the calculation of the real critical load of plane frame structures in the elastic–plastic domain and determines the corresponding effective length factors.

This paper presents the stress-strain analysis of terrain using the finite element method in the settlement Medaković in Belgrade during the construction and occupation of the eighth floor residential building. The slope stability analysis was performed using the finite element method. Application the finite element method, with the use of proposed incremental procedure has shown some advantages compared to the classical methods of stability analysis. First of all, using this method, it is possible to assess at any time the stress and strain values in terrain. Based on these values, it is possible to determine: zones of failure (local and/or general), critical sliding surface and reliable safety factor The obtained results are of great significance for the most part of the Belgrade terrain which was built up in a similar way and in the last few decades has been intensively urbanized. It has to be emphasized that the proposed stress-strain procedure has its application in construction of highways and landfills, both in civil engineering and mining engineering.

Pile foundations are frequently loaded by horizontal forces. In such cases, it is important to calculate lateral capacity of vertical piles. It is governed by the strength of the surrounding soil i.e. geotechnical capacity or pile strength parameters i.e. structural capacity of a pile. In this paper, geotechnical capacity is analysed first, and then the Rankine's, Broms' and Brinch-Hansen's methods for calculating ultimate bearing capacity of a single pile under lateral loads are presented. In accordance with complex geological conditions, which are very often in Serbia, Brinch-Hansen's method has an advantage over the other two methods. It can be applied both to uniform and layered soils under drained or undrained conditions. This is highly important for foundation of structures and landslide's remedial measures, too. Accordingly, load capacity calculation of a pile group is presented as well. In the case of homogenous surrounding soil, deformations of laterally loaded piles may be determined by elastic analysis. However, in the case of complex geological conditions, these deformations may be calculated by the concept of coefficient of subgrade reaction or by p-y curves, too. Finally, numerical analysis for calculation of geotechnical capacity and pile head displacement of laterally loaded piles for foundation of Clinker Bin in Beocin is presented.

In this paper the phenomenon of instability of frames in elasto-plastic domain was investigated. Numerical analysis was performed by the finite element method. Stiffness matrices were derived using the trigonometric shape functions related to exact solution of the differential equation of bending according to the second order theory. When the buckling of structure occurs in plastic domain, it is necessary to replace the constant modulus of elasticity E with the tangent modulus Et. Tangent modulus is stress dependent function and takes into account the changes of the member stiffness in the inelastic range. For the purposes of numerical investigation in this analysis, part of the computer program ALIN was created in a way that this program now can be used for elastic and elasto-plastic stability analysis of frame structures. This program is developed in the C++ programming language. Using this program, it is possible to calculate the critical load of frames in the elastic and inelastic domain. In this analysis, the algorithm for the calculation of buckling lengths of compressed columns of the frames was also established. The algorithm is based on the calculation of the global stability analysis of frame structures. Results obtained using this algorithm were compared with the approximate solutions from the European (EC3) and national (JUS) standards for the steel structures. By the given procedure in this paper it is possible to follow the behavior of the plane frames in plastic domain and to calculate the real critical load in that domain.