scholarly journals Analysis of Partial Factors for New EN 1990 Basis of Design

2017 ◽  
Vol 17 (1) ◽  
pp. 131-136
Author(s):  
Jana Marková
Keyword(s):  
Structural Design ◽  
Structural Glass ◽  
Structural Members ◽  
Limit States ◽  
New Generation ◽  
Ultimate Limit ◽  
Construction Works

Abstract Presently the new generation of Eurocodes is under development. It is expected that the basis of structural design given in current EN 1990 will be considerably revised including the format for load combinations in the Ultimate Limit States and new categorisation of consequence classes for construction works. It is expected that the partial factors for self-weight of structural members could be reduced and factors for variable loads more differentiated. Calibration of partial factors should be performed for actions and materials including also structural glass and FRP polymers.

Applications of Vector Evaluated Genetic Algorithms (VEGA) in Ultimate Limit State Based Ship Structural Design

2014 ◽  
Author(s):  
Owen Hughes ◽  
Ming Ma ◽  
Jeom Kee Paik
Keyword(s):  
Genetic Algorithms ◽  
Structural Design ◽  
Limit State ◽  
Structural Safety ◽  
Wall Structure ◽  
Ultimate Limit State ◽  
Thin Wall ◽  
Limit States ◽  
Multi Objective ◽  
Ultimate Limit

Ship structural design often deals with multiple objectives such as weight, safety, and cost. These objectives usually conflict with each other, and optimizing a particular solution with respect to a single objective can result in unacceptable results with respect to the other objectives. A reasonable solution to a multi-objective problem is to investigate a set of solutions, each of which satisfies the objectives at an acceptable level without being dominated by any other solution. Genetic algorithms have been demonstrated to be particularly effective to determine excellent solutions to these problems. In this paper a multi-objective GA, called Vector Evaluated Genetic Algorithm (VEGA) is formulated and used to optimize a large and complex thin-wall structure (a complete cargo hold of a 200,000 ton oil tanker) on the basis of weight, safety and cost. The structure weight and cost and all of the stresses are calculated using a realistic finite element model. The structure adequacy is then evaluated using the ALPS/ULSAP computer program (Paik and Thayamballi, 2003) which can efficiently evaluate all six ultimate limit states for stiffened panels and grillages. This example was chosen because the initial design is severely inadequate. The results show that the proposed method can perform ultimate strength based structural optimization with multi-objectives, namely minimization of the structural weight and cost and maximization of structural safety, and also that the method is very robust.

scholarly journals Reliability of Concrete Elements Designed for Alternative Load Combinations Provided in Eurocodes

10.14311/382 ◽  
2003 ◽  
Vol 43 (1) ◽  
Author(s):  
M. Holický ◽  
J. Marková
Keyword(s):  
Structural Design ◽  
Structural Reliability ◽  
Reliability Theory ◽  
Probabilistic Methods ◽  
European Standard ◽  
Limit States ◽  
Design Procedures ◽  
Characteristic Features ◽  
Concrete Elements ◽  
Ultimate Limit

The basic European standard for design of buildings and other engineering works, EN 1990 "Basis of structural design", provides alternative design procedures, for which national choice is allowed. One of the most important questions concerns three fundamental combinations of actions for persistent and transient design situations in the Ultimate limit states. Simple examples of reinforced concrete elements show, that the alternative load combinations may lead to considerably different reliability levels. Probabilistic methods of structural reliability theory are used to identify characteristic features of each combination and to formulate recommendations. However, further calibration studies are urgently needed in order to prepare National annexes to EN 1990 on time.

scholarly journals Some relevant aspects of footbridge vibrations

2002 ◽  
Vol 2 (4) ◽  
pp. 281-289
Author(s):  
Ana Spasojevic ◽  
Djordje Djordjevic ◽  
Marija Spasojevic ◽  
Novak Spasojevic
Keyword(s):  
Structural Design ◽  
Natural Frequencies ◽  
Weight Ratio ◽  
Structural Systems ◽  
Live Load ◽  
Limit States ◽  
Codes Of Practice ◽  
Vibration Serviceability ◽  
Bridge Structures ◽  
Ultimate Limit

Considering the contemporary structural inaterials that are becoming more resistant, having higher strength to weight ratio, and the fact that live load of footbridges is low, the design based on static analysis only, respecting ultimate limit states requirements, leads to slender bridge structures for pedestrian and cycle track use. As a consequence, stiffness and masses decrease, facing lively, easy to excite structures, with smaller natural frequencies. The excitation of a footbridge by a pedestrian passing over it can be unpleasant for a person walking or standing on the bridge, but usually not destructive for the structure itself. Recent experiences regarding dynamic behavior of slender footbridges have especially shown that vibration serviceability limit states are very important requirements in any structural design. We are presenting a general algorithm for analytical testing of dynamic parameters of structures, calculation of deflection, thus speed and acceleration of superstructure under human-induced excitation, as predicted by Eurocode, British and Canadian standards in use, since no Yugoslav code deals with the problem. The evaluated system is a footbridge in a system of a simply supported concrete girder. The presented model is used to show correspondence of results, obtained by the algorithm, with the results obtained using the simplified methods suggested by the Codes of Practice, since the latter exists only for certain structural systems.

Pull-Out Performance of T-Stub End Plate Connected To Concrete Filled Thin-Walled Steel Tube (CFTST) using Lindapter Hollo-Bolts

2018 ◽  
Vol 15 (1) ◽  
pp. 59
Author(s):  
NAZRUL AZMI AHMAD ZAMRI ◽  
CLOTILDA PETRUS ◽  
AZMI IBRAHIM ◽  
HANIZAH AB HAMID
Keyword(s):  
Limit Load ◽  
Steel Tube ◽  
Limit States ◽  
End Plate ◽  
Pull Out ◽  
Pullout Load ◽  
Thin Walled ◽  
Stub End ◽  
Concrete Filled Steel Tubes ◽  
Ultimate Limit

The application of concrete filled steel tubes (CFSTs) as composite members has widely been used around the world and is becoming popular day by day for structural application especially in earthquake regions. This paper indicates that an experimental study was conducted to comprehend the behaviour of T-stub end plates connected to concrete filled thin-walled steel tube (CFTST) with different types of bolts and are subjected to pullout load. The bolts used are normal type bolt M20 grade 8.8 and Lindapter Hollo-bolt HB16 and HB20. A series of 10 mm thick T-stub end plates were fastened to 2 mm CFTST of 200 mm x 200 mm in cross-section. All of the specimens were subjected to monotonic pull-out load until failure. Based on test results, the Lidapter Hollo-bolts showed better performance compare to normal bolts. The highest ultimate limit load for T-stub end plate fasten with Lindapter Hollo-bolt is four times higher than with normal bolt although all end plates show similar behaviour and failure mode patterns. It can be concluded that T-stub end plate with Lindapter Hollo-bolt shows a better performance in the service limit and ultimate limit states according to the regulations in the design codes.

scholarly journals Floating-bending tensile-integrity structures

2021 ◽  
Vol 8 (1) ◽  
pp. 89-95
Author(s):  
Micol Palmieri ◽  
Ilaria Giannetti ◽  
Andrea Micheletti
Keyword(s):  
Structural Design ◽  
Membrane Systems ◽  
Limit States ◽  
Form Finding ◽  
Supported Membrane ◽  
Tensegrity Systems ◽  
Matlab Implementation ◽  
Diamond Type ◽  
Conceptual Work

Abstract This is a conceptual work about the form-finding of a hybrid tensegrity structure. The structure was obtained from the combination of arch-supported membrane systems and diamond-type tensegrity systems. By combining these two types of structures, the resulting system features the “tensile-integrity” property of cables and membrane together with what we call “floating-bending” of the arches, a term which is intended to recall the words “floating-compression” introduced by Kenneth Snelson, the father of tensegrities. Two approaches in the form-finding calculations were followed, the Matlab implementation of a simple model comprising standard constant-stress membrane/cable elements together with the so-called stick-and-spring elements for the arches, and the analysis with the commercial software WinTess, used in conjunction with Rhino and Grasshopper. The case study of a T3 floating-bending tensile-integrity structure was explored, a structure that features a much larger enclosed volume in comparison to conventional tensegrity prisms. The structural design of an outdoor pavilion of 6 m in height was carried out considering ultimate and service limit states. This study shows that floating-bending structures are feasible, opening the way to the introduction of suitable analysis and optimization procedures for this type of structures.

scholarly journals Investigation of horizontal forces result in railway viaduct with curved truck

2013 ◽  
Vol 12 (2) ◽  
pp. 047-054 ◽  
Author(s):  
Piotr Olaszek ◽  
Juliusz Cieśla ◽  
Waldemar Szaniec
Keyword(s):  
Railway Track ◽  
Bridge Structure ◽  
Dynamic Effects ◽  
Passenger Cars ◽  
Limit States ◽  
Railway Line ◽  
Vertical Displacements ◽  
Special Train ◽  
Ultimate Limit ◽  
Crossing Test

In the report some investigations of bridge structure, connected with the adaptation of the railway line to speeds up to 200 km/h for conventional trains and up to 250 km/h for tilting trains were presented. A railway track is the characteristic feature of tested viaduct, because the truck is curved over the whole length of span with radius of R = 2600 m. The tests of the viaduct required the verification of influence of the dynamic effects on the ultimate limit states which corresponded to the safety of structure, as well as the serviceability limit states, related to the safety of driving and the travellers’ comfort. In frames of investigations, a special train comprised of two locomotives and four passenger cars, was used with speeds in the range between 10 and 200 km/h. The report focuses on the problems addressing the influence of horizontal actions in the case of bridge with curved truck. The measurements of the horizontal and vertical displacements as well as the accelerations of span, and the speed of crossing test train were executed. The measured and theoretically calculated chosen courses of displacements and accelerations were introduced. The degree of divergence between measured and calculated values was analysed.

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