scholarly journals Failure Assessment of Embankment Dam Elements: Case Study of the Pirot Reservoir System

2022 ◽  
Vol 12 (2) ◽  
pp. 558
Author(s):  
Dragan Rakić ◽  
Milan Stojković ◽  
Damjan Ivetić ◽  
Miroslav Živković ◽  
Nikola Milivojević

The paper presents a functionality investigation of the key dam elements based on finite element analysis. A detailed analysis of filtration processes, dam strength, and the surrounding rock mass was conducted. Dam elements whose potential damage could jeopardize the normal functioning of the embankment dam have been identified. A particular emphasis was placed on the analysis of dam elements that have been identified as weak points. A numerical analysis of the impact of individual grout curtain zone failure on leakage under the dam body, a strength analysis of the overflow section, as well as the analysis of the slope stability that can compromise the functioning of the spillway have been performed. To analyze the partial stability of individual structural elements, a new measure of local stability was introduced as the remaining load-bearing capacity. As a case study, the Zavoj dam, which is a part of the Pirot reservoir system in the Republic of Serbia, was used. Investigation revealed that local damage to the grout curtain will not significantly increase leakage under the dam body, the overflow section is one of the most robust elements of the dam, but the slope above the spillway can compromise the functioning of the overflow and thus the safety of the entire dam. Based on the analysis of the results of the remaining load-bearing capacity, the dependence of the spillway capacity on earthquake intensity has been defined. The established relationship represents a surrogate model for further assessment of dynamic resilience of the complex multipurpose reservoir system, within the scope of the advanced reservoir system management.

2016 ◽  
Vol 2 (5) ◽  
pp. 221-225 ◽  
Author(s):  
Mahdi Bamdad ◽  
Abdolreza Sarvghad Moghadam ◽  
Mohammad Javad Mehrani

Many methods have been developed in order to study the impact behavior of solids and structures. Two common methods are finite element and experimental method. The nonlinear finite element method is one the most effective methods of predicting the behavior of RC beams from zero-load to failure and its fracture, yield and ultimate strengths. The advantage of this method is its ability to make this prediction for all sections of the assessed RC beam and all stages of loading. This paper compares the experimental results obtained for a RC frame with the numerical results calculated by ABAQUS software, and plots both sets of results as hysteresis–displacement diagrams. This comparison shows that the numerical FEM implemented via ABAQUS software produce valid and reliable results for load bearing capacity of RC frames subjected to cyclic loads, and therefore has significant cost and time efficiency advantages over the alternative approach


Author(s):  
Mohammad Reza Ghaemdoust ◽  
Omid Yousefi ◽  
Kambiz Narmashiri ◽  
Masoumeh Karimian

In view of development and repair costs, support of structures is imperative. Several factors, for example, design and calculation errors, absence of appropriate installation, change of structures application, exhaustion, seismic tremor, fire and natural conditions diminish their strength. In such cases, structures have need of rehabilitation and restoration to achieve their original performance. One of the most up to date materials for retrofitting is carbon fiber reinforced polymer (CFRP) that can provide an amount of restriction to postpone buckling of thin steel walls. This paper provides a numerical and experimental investigation on CFRP strengthened short steel tubes with initial horizontal and vertical deficiency under compression. Ten square and circular specimens were tested to study effects of the following parameters: (1) position of deficiency, horizontal or vertical; (2) tube shape, square or circular; (3) CFRP strengthening. In the experiments, axial static loading was gradually applied and for the numerical study three-dimensional (3D) static nonlinear analysis method using ABAQUS software was performed. The results show that deficiency reduces load-bearing capacity of steel columns and the impact of horizontal deficiency is higher than the impact of vertical deficiency, in both square and circular tubes. Use of CFRP materials for strengthening of short steel columns with initial deficiency indicates that fibers play a considerable role on increasing load bearing capacity, reducing stress at the damage location, preventing deformation caused by deficiency and delaying local buckling. Both numerical and experimental outcomes are in good agreement, which underlines the accuracy of the models adopted.


2016 ◽  
Vol 711 ◽  
pp. 564-571 ◽  
Author(s):  
Thomas Gernay

The use of high strength concrete (HSC) in multi-story buildings has become increasingly popular. Selection of HSC over normal strength concrete (NSC) allows for reducing the dimensions of the columns sections. However, this reduction has consequences on the structural performance in case of fire, as smaller cross sections lead to faster temperature increase in the section core. Besides, HSC experiences higher rates of strength loss with temperature and a higher susceptibility to spalling than NSC. The fire performance of a column can thus be affected by selecting HSC over NSC. This research performs a comparison of the fire performance of HSC and NSC columns, based on numerical simulations by finite element method. The thermal and structural analyses of the columns are conducted with the software SAFIR®. The variation of concrete strength with temperature for the different concrete classes is adopted from Eurocode. Different configurations are compared, including columns with the same load bearing capacity and columns with the same cross section. The relative loss of load bearing capacity during the fire is found to be more pronounced for HSC columns than for NSC columns. The impact on fire resistance rating is discussed. These results suggest that consideration of fire loading limits the opportunities for use of HSC, especially when the objective is to reduce the dimensions of the columns sections.


2014 ◽  
Vol 665 ◽  
pp. 196-202
Author(s):  
Yi Qing Guo ◽  
Ping Zhou Cao

In order to study the performance of lightweight energy-saving composite floor, the finite element models of composite floor were established, which was based on the composite floor specimens test research. The finite element models were verified rationally and correctly in the paper, through compared with the composite floor test results. The finite element model can be used to analyze the load-bearing capacity of composite floor. Various influencing factors of composite floor with simply supported end were analyzed, such as the span of self-tapping screw, the diameter of self-tapping screw, the strength of thin panel and the elastic modulus of thin panel, etc. The results show that the load-bearing capacity of composite floor increases with the increase of the number of self-tapping screw, the diameter of self-tapping screw, the strength of thin panel and the elastic modulus of thin panel, etc. The load-bearing capacity calculate formula of composite floor was proposed.


2012 ◽  
Vol 204-208 ◽  
pp. 995-998
Author(s):  
Yun Yun Li ◽  
Bao Sheng Yang

This paper studies the working mechanism, ductility, and ultimate load bearing capacity of the composite columns through axial load bearing capacity experiments on eight steel skeleton-steel pipes reinforced composite concrete columns. The results show that the collaborative work between the steel pipe, steel skeleton and concrete can effectively improve the bearing capacity of the column, delay or inhibit the spread of shear diagonal cracks in the concrete and improve the ductility of the column. In addition, the finite element software ANSYS is used to digitally simulate the whole process of axial pressure test, and the resulting load-displacement curves and experimental curves agree fairly well.


Vestnik MGSU ◽  
2021 ◽  
pp. 1567-1572
Author(s):  
Emmanuel Mikerego ◽  
Donatien Nduwimana

Introduction. This paper presents the results of an assessment of the impact of fire on the bearing capacity of the ordinary concrete, to be taken into account in the rehabilitation of fire-damaged reinforced concrete structures in Burundi. Materials and methods. Experimental samples of the ordinary concrete made respectively of coarse river aggregates and crushed coarse quarry aggregates were prepared and subjected to different heating temperatures (250, 350, 450, 600 and 900 °C) simulating the fire. After natural cooling, experimental samples were subjected to compression test; and diagrams showing the loss of the load-bearing capacity of the ordinary concrete used in reinforced concrete structures in Burundi were drawn. Results. Negative impact of the fire on the load-bearing capacity of the ordinary concrete occurs above of 350 °C of heating temperature. Concrete made of crushed coarse quarry aggregates loses 50 and 78 % of its bearing capacity at around 525 and 900 °C of heating temperature, respectively. Similarly, concrete made of coarse river aggregates loses 50 and 70 % of its load-bearing capacity respectively at 600 and 900 °C of heating temperature. An evaluation curve of the after-fire bea­ring capacity of the concrete used in reinforced concrete structures in Burundi is established. Conclusions. The negative impact of the fire on the load-bearing capacity of the ordinary concrete occurs above of 350 °C of heating temperature. Concretes made of crushed coarse quarry aggregates and concrete made of coarse river aggregates lose 50 % of its bearing capacity at around 525 and 600 °C of heating temperature respectively. Knowing the heating temperature that the fire-damaged reinforced concrete structure has undergone is indispensable in deciding on its demolition or rehabilitation.


Author(s):  
Mariusz Wesołowski ◽  
Krzysztof Blacha

Airfield pavement is a marked and appropriately prepared surface of an airfield functional element that performs a definite function in aircraft operations. The structure of airfield pavement is most often composed of a set of layers whose task is to absorb and transfer loads coming from moving aircraft onto the ground in a way that ensures its definite durability. Structures of airfield pavements are designed for a definite exploitation period on the assumption of predicted volume and structure of the air traffic. Safety of air operations conducted by aircrafts on airfield pavements depends mainly on the state of bearing capacity of their construction. Due to the above, control tests of bearing capacity shall be periodically conducted, since information regarding the current state of an airfield pavement constitutes the basis for decisions concerning the types of aircrafts permitted to land and take off, traffic volume and dates of starting renovation or modernization works. In addition to loads generated by aircraft, on the condition of airfield pavement load bearing capacity is influenced by many external factors, including weather conditions. The ACN-PCN non-destructive method is currently used in the assessment of airfield bearing capacity, which has been introduced by ICAO (ICAO 2013). According to its assumptions, the airfield construction bearing capacity may be expressed in PCN or permissible number of air operations. The fundamental problem by measuring airfield pavements is to assume the correct computational model of a structure, which describes the way of cooperation and mechanical properties of individual layers. This paper contains the way of assessing and description of PCN as well as presentation of the possibility of expressing bearing capacity results by determination of permissible number of aircraft operations. There is also interrelation between PCN and the permissible number of aircraft operations presented in a graphic way.


Author(s):  
Kamil Burkovič ◽  
Vojtěch Buchta

Abstract A design of the load-bearing capacity and settlement of a pilot base is usually based on the assumption that all of the load from the top of the building is transferred only by pilots. The influence of the adjacent connecting structures, which are in contact with the ground (pile cap, slab, block, belt, etc.), is usually ignored. The necessary data from the experimental measurement of the impact of these structures, concerning the overall bearing capacity of the foundations, was obtained on the testload device (Stand), in the area of Faculty of Civil Engineering, VŠB-TU of Ostrava. The progress of the experiment and the results of the load tests are listed in this paper


2020 ◽  
Vol 6 ◽  
Author(s):  
Mohammad Reza Chenaghlou ◽  
Mohammad Kheirollahi ◽  
Karim Abedi ◽  
Ahmad Akbari ◽  
Aydin Fathpour

Biomimicry studies have attracted significant attention in research and practice, leading to effective engineering solutions to develop new types of structures inspired by natural systems. The objective of this study is to employ natural structures' inherent adaptivity under changing loading conditions. Three new types of compound elements are proposed that are able to improve the structure load-bearing capacity through passive inherent adaptivity. A self-centering system, inspired by the human spine, which comprises a column pre-stressed through cables, is employed as a kinematic isolator. A similar self-centering system is applied to increase the load-bearing capacity of unreinforced masonry columns. An axially loaded element, inspired by the bamboo stem, which comprises a steel core reinforced by a series of cylindrical plates that are encased in a steel tube, is employed to control the onset of instability in long-span truss structures. Application to typical frame, masonry, and truss structures is investigated through finite element analysis. Results show that the proposed compound elements are effective to increase the structure load-bearing capacity and to reduce the response under seismic excitation owning to their inherent adaptive features.


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