scholarly journals DETERMINATION OF REGULATORY RELIABILITY FOR DEFORMATION OF REINFORCED-CONCRETE FLEXIBLE STRUCTURES

2019 ◽  
Vol 21 (5) ◽  
pp. 115-126
Author(s):  
E. P. Gerasimov
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
Structural Reliability ◽  
Limit State ◽  
Flexible Structures ◽  
Probabilistic Methods ◽  
Methods Of Calculation ◽  
State Method ◽  
Definition Of

Strength, stiffness, crack resistance requirements must be specified for any structure. These requirements are provided by the appropriate calculations. Compliance with all requirements ensures the design reliability. But due to the fact that structural analysis is performed by the limit state method, the numerical value of the reliability cannot be determined. This can be done only by applying probabilistic methods of calculation. One of the major obstacles to the use of probabilistic methods is the lack of standardized values of the structural reliability (normative reliability).Although probabilistic methods of calculation were developed in late in the 20th century, the assignment of normative reliability values encountered serious obstacles. The most serious obstacle was the consideration of the failure consequences as some consequences were quantifiable. On the other hand, much work concerned the assignment of normative structural reliability based on their bearing capacity. Only few works related to the reliability normalization using deformation and crack resistance.This paper deals with the regulatory definition of reliability using the deformation of reinforced-concrete bendings based on physiological requirements. A method for determining the normative reliability based on human sensitivity to fluctuations is proposed. The normative reliability of precast slabs is determined using the proposed method.

Influence of Human Error on Structural Reliability

2017 ◽  
Author(s):  
Eric Brehm ◽  
Robert Hertle ◽  
Markus Wetzel
Keyword(s):  
Human Error ◽  
Structural Reliability ◽  
Failure Modes ◽  
Structural Model ◽  
Limit State ◽  
Design Procedure ◽  
Material Strength ◽  
Limit States ◽  
The Impact

In common structural design, random variables, such as material strength or loads, are represented by fixed numbers defined in design codes. This is also referred to as deterministic design. Addressing the random character of these variables directly, the probabilistic design procedure allows the determination of the probability of exceeding a defined limit state. This probability is referred to as failure probability. From there, the structural reliability, representing the survival probability, can be determined. Structural reliability thus is a property of a structure or structural member, depending on the relevant limit states, failure modes and basic variables. This is the basis for the determination of partial safety factors which are, for sake of a simpler design, applied within deterministic design procedures. In addition to the basic variables in terms of material and loads, further basic variables representing the structural model have to be considered. These depend strongly on the experience of the design engineer and the level of detailing of the model. However, in the clear majority of cases [1] failure does not occur due to unexpectedly high or low values of loads or material strength. The most common reasons for failure are human errors in design and execution. This paper will provide practical examples of original designs affected by human error and will assess the impact on structural reliability.

Mechanical properties of confirmat screws corner joints made of native wood and wood-based composites

2019 ◽  
Vol 105 ◽  
pp. 76-84
Author(s):  
NADEŽDA LANGOVÁ ◽  
PAVOL JOŠČÁK
Keyword(s):  
Mechanical Properties ◽  
Carrying Capacity ◽  
Limit State ◽  
Calculated Data ◽  
Statistical Processing ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Characteristic Values ◽  
State Method

Mechanical Properties of Confirmat Screws Corner Joints Made of Native Wood and Wood-Based Composites. The aim of this investigation was to design and determine the mechanical properties of confirmat screws corner joints made of native wood and wood-based composites. The objective of the study was to ascertain the stiffness and load carrying capacity of joints that differed in the diameter and length of confirmat type screw, as well as in the kind of materials. The results include statistical processing of measured and calculated data, and evaluation of the influence of selected factors on mechanical properties. The results are applied to the calculation of the characteristic values of the properties and to the determination of the equations for their calculation for other values of the selected factors. The characteristic values are used for the evaluation of the joints according to the limit state method.

On Strength Reserve Assessment for Prismatic Folded Plate Roof Structures

2015 ◽  
Vol 725-726 ◽  
pp. 922-927
Author(s):  
Vitaly Kolchunov ◽  
Evgeny Osovskih ◽  
Pavel Afonin
Keyword(s):  
Numerical Simulation ◽  
Reinforced Concrete ◽  
Residual Strength ◽  
Limit State ◽  
Experimental Studies ◽  
Limit States ◽  
Mechanical Loads ◽  
Methods Of Calculation ◽  
Environmental Actions ◽  
Strength Reserve

The paper presents the results of experimental studies and numerical simulation of straining and failure of reinforced concrete folded-plate roof structures in limit and out-of-limit states performed on models and real structures, taking into account the combined mechanical loads and environmental actions. The results of the study show that in the process of reconstruction design for concrete prismatic roof structures of operated industrial and public buildings, along with the traditional limit state methods of calculation it is reasonable to carry out a residual strength reserve analysis.

LIMIT AND SHAKEDOWN ANALYSIS UNDER UNCERTAINTY

2014 ◽  
Vol 11 (03) ◽  
pp. 1343008 ◽  
Author(s):  
MANFRED STAAT
Keyword(s):  
Structural Reliability ◽  
High Reliability ◽  
Limit State ◽  
Mathematical Optimization ◽  
Element Model ◽  
General Purpose ◽  
State Function ◽  
Limit State Function ◽  
Shakedown Analysis ◽  
Definition Of

Structural reliability analysis is based on the concept of a limit state function separating failure from safe states of a structure. Upper and lower bound theorems of limit and shakedown analysis are used for a direct definition of the limit state function for failure by plastic collapse or by inadaptation. Shakedown describes an asymptotic and therefore time invariant structural behavior under time variant loading. The limit state function and its gradient are obtained from a mathematical optimization problem. The method is implemented into a general purpose finite element model (FEM) code. Combined with first-order methods/second-order methods (FORM/SORM) robust and precise analyses can be performed for structures with high reliability. This approach is particularly effective because the sensitivities which are needed by FORM/SORM are derived from the solution of the deterministic problem.

Calculation Models of the Bearing Capacity of Span Reinforced Concrete Structure Support Zones

2019 ◽  
Vol 968 ◽  
pp. 209-226
Author(s):  
Vasyl M. Karpiuk ◽  
Yulia A. Syomina ◽  
Diana V. Antonova
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
Cross Sections ◽  
Concrete Structure ◽  
Strain State ◽  
Complex Stress ◽  
Deformation Analysis ◽  
Reinforced Concrete Structures ◽  
Reinforced Concrete Structure

Experience gained in design, erection and operation of span reinforced concrete structures has proved that practically all of them are subject to complex stress-strain state. At that, the researchers pay considerable greater attention to calculation of strength, deformation analysis and determination of crack resistance in normal cross-sections than to calculation of their support zones, including oblique sections, which results are generally taken into account for determining the section dimensions and the quantity of the cross reinforcement.

scholarly journals Probability analysis of an embedded water tank

2020 ◽  
Vol 310 ◽  
pp. 00014
Author(s):  
Katarína Tvrdá
Keyword(s):  
Reinforced Concrete ◽  
Probabilistic Method ◽  
Limit State ◽  
Probability Analysis ◽  
Probabilistic Methods ◽  
Water Tank ◽  
Building Structures ◽  
Load Pressure ◽  
Concrete Tank ◽  
Building Standards

The design of building structures must fulfil specific regulations, in our case, different building standards, among them Eurocodes. In addition to deterministic procedures in structural design, these standards also allow probabilistic procedures. The embedded tank loaded with soil and liquid is solved by the probability analysis using ANSYS, which contains several probabilistic methods. The reinforced concrete tank is solved by the RSM probabilistic method, which uses the well-known Monte-Carlo method in the background. Input parameters (material properties of soil and reinforced concrete, load - pressure from water, geometric data - change of both wall and tank bottom thickness) are entered into the calculation with certain aberrances allowed by standards in the construction and loading of structures. The results are also sets of probabilistic variables with a certain variance, as opposed to a deterministic calculation, where only one value results. These procedures, which use statistical methods, have been at the forefront in recent decades. At the end of the paper, some results of the analysis of embedded reinforced concrete water tank (deterministic and probabilistic procedure) in state of tank failure on the second limit state are presented.

Reliability Studies on Timber Data from Nigerian Grown Iroko Tree (Chlorophora excelsa) as Bridge Beam Material

2012 ◽  
Vol 8 ◽  
pp. 17-35 ◽  
Author(s):  
J.I. Aguwa ◽  
S. Sadiku
Keyword(s):  
Compressive Strength ◽  
Reliability Analysis ◽  
Structural Reliability ◽  
Limit State ◽  
Strength Properties ◽  
Ultimate Limit State ◽  
Analysis And Design ◽  
Reliability Method ◽  
Bridge Beams

This paper provides the results of structural reliability analysis carried out on the data of Nigerian grown Iroko tree (Chlorophora excelsa), to ascertain its structural performance as timber bridge beams. Five pieces of 50mm x 75mm x 3600mm of Nigerian grown Iroko hardwood were bought, seasoned naturally and 200 pieces of samples were prepared for determination of their strength properties, (which include bending strength parallel to grain, tensile strength parallel to grain, compressive strength parallel to grain, compressive strength perpendicular to grain and shear strength parallel to grain) at a moisture content of 18%, in accordance with the British Standard BS 373 of 1957. Statistical analysis was carried out using the strength properties for determination of mean, standard deviation, coefficient of variations, confidence limits and Chi-Square goodness of fits. Structural analysis and design of a timber bridge beam using the determined data from the Nigerian grown Iroko timber, in accordance with BS 5268 were carried out under the Ultimate Limit State of loading (ULSL). Reliability analysis was carried out to ascertain its level of safety using First-Order Reliability Method (FORM). Sensitivity analysis was also carried out by varying the depth of beam, imposed live load, breadth of the beam, unit weight of the Iroko timber, span of the beam as well as the end bearing length. The result revealed that the Nigerian grown Iroko timber is a satisfactory structural material for timber bridge beams at depth of 400mm, breadth of 150mm and span of 5000mm under the ULSL. The probabilities of failure of the Nigerian grown Iroko timber bridge beam in bending, shear, compression and deflection are respectively, under the specified conditions of loading.

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