scholarly journals Load and resistance factors for earth retaining, reinforced concrete hydraulic structures based on a reliability index (β) derived from the Probability of Unsatisfactory Performance (PUP) : phase 2 study

2021 ◽  
Author(s):  
Robert Ebeling ◽  
Barry White
Keyword(s):  
Reinforced Concrete ◽  
Hydraulic Structure ◽  
Limit State ◽  
Hydraulic Structures ◽  
Army Corps ◽  
Second Phase ◽  
Limit States ◽  
Two Phase ◽  
Topic Area ◽  
Load And Resistance Factor

This technical report documents the second of a two-phase research and development (R&D) study in support of the development of a combined Load and Resistance Factor Design (LRFD) methodology that accommodates geotechnical as well as structural design limit states for design of the U.S. Army Corps of Engineers (USACE) reinforced concrete, hydraulic navigation structures. To this end, this R&D effort extends reliability procedures that have been developed for other non-USACE structural systems to encompass USACE hydraulic structures. Many of these reinforced concrete, hydraulic structures are founded on and/or retain earth or are buttressed by an earthen feature. Consequently, the design of many of these hydraulic structures involves significant soil structure interaction. Development of the required reliability and corresponding LRFD procedures has been lagging in the geotechnical topic area as compared to those for structural limit state considerations and have therefore been the focus of this second-phase R&D effort. Design of an example T-Wall hydraulic structure involves consideration of five geotechnical and structural limit states. New numerical procedures have been developed for precise multiple limit state reliability calculations and for complete LRFD analysis of this example T-Wall reinforced concrete, hydraulic structure.

Combined flexure and torsion of I-shaped steel beams

1989 ◽  
Vol 16 (2) ◽  
pp. 124-139 ◽  
Author(s):  
Robert G. Driver ◽  
D. J. Laurie Kennedy
Keyword(s):  
Limit State ◽  
Bending Moment ◽  
Phase Behaviour ◽  
Inelastic Interaction ◽  
Steel Beams ◽  
Ultimate Limit State ◽  
Second Phase ◽  
Design Standards ◽  
Limit States ◽  
Interaction Diagram

Design standards provide little information for the design of I-shaped steel beams not loaded through the shear centre and therefore subjected to combined flexure and torsion. In particular, methods for determining the ultimate capacity, as is required in limit states design standards, are not presented. The literature on elastic analysis is extensive, but only limited experimental and analytical work has been conducted in the inelastic region. No comprehensive design procedures, applicable to limit states design standards, have been developed.From four tests conducted on cantilever beams, with varying moment–torque ratios, it is established that the torsional behaviour has two distinct phases, with the second dominated by second-order geometric effects. This second phase is nonutilizable because the added torsional restraint developed is path dependent and, if deflections had been restricted, would not have been significant. Based on the first-phase behaviour, a normal and shearing stress distribution on the cross section is proposed. From this, a moment–torque ultimate strength interaction diagram is developed, applicable to a number of different end and loading conditions. This ultimate limit state interaction diagram and serviceability limit states, based on first yield and on distortion limitations, provide a comprehensive design approach for these members. Key words: beams, bending moment, flexure, inelastic, interaction diagram, I-shaped, limit states, serviceability, steel, torsion, torque, ultimate.

Experimental Study of Concrete Class Influence on Cracks Spacing

2014 ◽  
Vol 600 ◽  
pp. 558-568
Author(s):  
Omar Zorkane ◽  
Farid Chalah ◽  
Lila Chalah-Rezgui ◽  
Abderrahim Bali ◽  
Mohamed Nadib Oudjit
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Phase Ii ◽  
Normal State ◽  
Limit State ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Limit States ◽  
Continuous Beams ◽  
Real Size

The aim of this work is to study the cracking of reinforced concrete continuous beams by considering different classes of concrete. It is well known that the design of reinforced concrete structures includes three limit states (limit state of collapse, limit state of strain and limit state of cracking). The cracks in reinforced concrete structures are admitted in the phase II (cracked sections). Thus, the phenomenon of cracks formation can be treated as a normal state only when their openings are limited to avoid a permanent risk of collapse and ensure durability for the civil engineering concrete structures. The importance of this work is described by the tests made on reinforced concrete continuous beams in real size, under concentrated loads increasing from zero up to collapse, where the concrete class influence on the cracks spacing has been studied. As this wasnt theoretically investigated, the used references for an aim comparison were relative to experimentations made by Monnier and Kuczynski on an only one concrete class to the cracks openings and the spacing evaluation analysis The findings of the research reported in this paper show that there is no effect of the concrete class on the cracks spacing.

scholarly journals ANALYSIS OF NONLINEAR STATIC-DYNAMIC DEFORMATION OF REINFORCED CONCRETE FRAMES IN OUT-OF-LIMIT STATES

2021 ◽  
pp. 20-35
Author(s):  
N. V. Fedorova ◽  
Ngoc Tuyen Vu ◽  
M. D. Medyankin
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Dynamic Loading ◽  
Computational Analysis ◽  
Dynamic Deformation ◽  
Limit State ◽  
Concrete Frames ◽  
Limit States ◽  
Reinforced Concrete Frames ◽  
Nonlinear Static

Statement of the problem. The article presents a computational model, an algorithm for computational analysis and the results of calculating the nonlinear static-dynamic deformation of reinforced concrete frames in out-of-limit states caused by the sudden removal of one of the supporting structures. Results. To design a numerical model of the static-dynamic loading mode of a structural system, the LS-DYNA software package was used that makes use of a detailed 3D model implementing an explicit finite element method. During the computational analysis, the physical and mechanical characteristics of the deformation of materials were taken in three variants: those obtained based on the experimental data by G. A. Geniev, the experimental data by N. V. Fedorova and M. D. Medyankin under the static-dynamic uniaxial testing mode of a limited number of standard samples of prisms and according to the Russian standards SP (СП) 385.1325800.2018. Conclusions. Numerical analysis of the static-dynamic deformation of the reinforced concrete framerod system of a multi-storey building has established that the differentiated accounting of the quantitative value of the concrete viscosity modulus and, accordingly, the time and level of static-dynamic loading of the structure allows one to identify the criteria for the special limit state of the elements of reinforced concrete structural systems of buildings and structures in a more rigid manner.

scholarly journals Strengthening of Concrete Column by Using the Wrapper Layer of Fibre Reinforced Concrete

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5432
Author(s):  
Peter Koteš ◽  
Martin Vavruš ◽  
Jozef Jošt ◽  
Jozef Prokop
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Limit State ◽  
Fibre Reinforced Concrete ◽  
Limit States ◽  
Load Bearing Capacity ◽  
Concrete Core ◽  
Fibre Concrete ◽  
Special Cases ◽  
Ultimate Limit

Structures and bridges are being designed on the proposed and requested design lifetime of 50 to 100 years. In practice, one can see that the real lifetime of structures and bridges is shorter in many cases, in some special cases extremely shorter. The reasons for the lifetime shortening can be increased of the load cases (e.g., due to traffic on bridges, or due to other uses of a structure), using the material of lower quality, implementation of new standards and codes according to Eurocode replacing older ones. During the whole lifetime the structures must be maintained to fulfil the code requests. If the constructions are not able to fulfil the Ultimate Limit States (ULS) and the Serviceability Limit State (SLS), the structures or bridges have to be strengthened (whole or its elements). The purpose of the paper is the presentation of using a layer of the fibre concrete for a columns’ strengthening. Using the fibre reinforced concrete (FRC) of higher tensile strength makes it possible to increase the load-bearing capacity of the cross-section the column. The contact between the old concrete (core of column) and newly added layer (around column) is very important for using that method of strengthening. In the article, there is also a comparison of the surface modification methods.

scholarly journals Research on Intelligent Evaluation System of Load-bearing Capacity of Existing Reinforced Concrete Bridge

2020 ◽  
Vol 165 ◽  
pp. 04056
Author(s):  
An Zhao ◽  
Qiang Xu ◽  
Jianyong Song
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Evaluation System ◽  
Limit State ◽  
Concrete Bridge ◽  
Parametric Modelling ◽  
Limit States ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Reinforced Concrete Bridge

The intelligent evaluation system of existing reinforced concrete bridge “BLP” is a special software for the load-bearing capacity rapid analysis and evaluation of the existing reinforced concrete bridge, which was developed by the Highway Research Institute of the Ministry of Transport. Based on the parametric modelling method, it can quickly and easily establish the finite element plane model of the bridge structure for the static analysis of ultimate bearing capacity limit states and serviceability limit state, under variety norms. And it can easily and quickly build variable-section beams and rebars, with the special module. According to the comprehensive modification method of the load-bearing capacity evaluation, it can automatically recommend checking sections, and automatically calculate partial modification coefficient of resistance effect, and conveniently judge the safety coefficient of the sections, and quickly get the results of bridge load-bearing capacity. In summary, this system can significantly improve the work efficiency and accuracy of load-bearing capacity for exiting reinforced concrete bridge. This paper introduces in detail the characteristics of the intelligent analysis technology, calculation principle and real bridge application examples of the system.

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.

scholarly journals Designing Reinforced Concrete Beams Containing Supplementary Cementitious Materials

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1248 ◽  
Author(s):  
Alessandro P. Fantilli ◽  
Francesco Tondolo ◽  
Bernardino Chiaia ◽  
Guillaume Habert
Keyword(s):  
Reinforced Concrete ◽  
Environmental Impact ◽  
Cement Content ◽  
Limit State ◽  
Carbon Dioxide Emission ◽  
Cementitious Materials ◽  
Reinforced Concrete Beams ◽  
Supplementary Cementitious Materials ◽  
Limit States ◽  
Ultimate Limit

If supplementary cementitious materials (SCMs) are used as binders, the environmental impact produced by cement-based composites can be reduced. Following the substitution strategy to increase sustainability, several studies have been carried out with the aim of measuring the mechanical properties of different concrete systems, in which a portion of Portland cement was substituted with SCMs, such as fly ashes. On the other hand, studies on the structural behavior of reinforced concrete (RC) elements made with SCMs are very scarce. For this reason, in this paper, a new procedure is introduced with the aim of fulfil a new limit state of sustainability, in accordance with the serviceability and ultimate limit states required by building codes. Although the environmental impact of concrete decreases with the reduction of cement content, the proposed approach shows that the carbon dioxide emission of an RC beam is not a monotonic function of the substitution rate of cement with SCMs. On the contrary, there are favorable values of such substitution rates, which fall within a well-defined range.

Fragility analysis of self-centering prestressed concrete bridge pier with external aluminum dissipators

2016 ◽  
Vol 20 (8) ◽  
pp. 1210-1222 ◽  
Author(s):  
Zhiliang Cao ◽  
Hao Wang ◽  
Tong Guo
Keyword(s):  
Reinforced Concrete ◽  
Prestressed Concrete ◽  
Fragility Curves ◽  
Limit State ◽  
Seismic Capacity ◽  
External Energy ◽  
Limit States ◽  
Performance Limit ◽  
Residual Drift ◽  
Capacity Evaluation

A novel self-centering prestressed concrete pier with external energy dissipators has been developed to realize seismic resilient performance and enhanced corrosion-resisting property. Self-centering capacity of the pier is provided by the unbonded post-tensioned tendons and damage is mostly concentrated on the replaceable dissipators. To investigate the seismic behavior of the proposed pier, a detailed analytical model considering interface opening and dissipator deformation was developed and verified through existing cyclic load tests. Based on the proposed model, a prototype reinforced concrete pier and a self-centering prestressed concrete pier with similar backbone curves are designed, and fragility analyses are conducted on the two piers through incremental dynamic analysis. One maximum drift-based performance limit state (i.e. collapse prevention) and two residual drift-based performance limit states (i.e. emergent usage and reconstruction) are defined for seismic capacity evaluation. Fragility curves indicate that the self-centering prestressed concrete pier has a slightly higher peak drift demand owing to its inferior dissipating capacity as compared with the reinforced concrete pier, while sustains a much lower residual drift demand due to its inherent self-centering characteristic.

Special Limit Condition Of Reinforced Concrete Structures And Its Normalization

2020 ◽  
pp. 4-9
Keyword(s):  
Reinforced Concrete ◽  
Limit State ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Functional Requirements ◽  
Limit States ◽  
Limit Condition ◽  
Load Bearing ◽  
Significant Strength ◽  
Special Limit

One of the ways to improve the resilience of buildings in the event of failure of the bearing structure or emergency, seismic effects is a more complete account of the behavior of elements and their mates at short-term action of loads and dynamics of change of the scheme of the bearing system of the building. To do this, it is advisable to allow more cracks to open, the development of deflections and partial destruction of some sections, which contradicts the current criteria for the first and second limit states that ensure the operational suitability of structures and buildings. Therefore, it is necessary to introduce specific standards of a special limit state for structures. A special limit state is the stage of operation of the structure after reaching the load-bearing capacity for the first and the deformation limits for the second limit states. Exceeding this state, in which the structures do not fully meet the functional requirements, leads to their collapse. The implementation of this limit state is most appropriate in load-bearing systems with a high degree of static indeterminability and constructive interaction of all bearing elements. The introduction and consideration of a special limit stress-strain state of reinforced concrete structures make it possible to detect significant strength and deformation reserves, even after significant fragmentation of the compressed concrete zone and, as a result, reducing the working section of the structure. As the main criteria of a particular limit state for reinforced concrete structures, it is recommended to adopt: the ultimate deformations of compressed concrete and tensile reinforcement with higher values than permissible under normal conditions; as well as the deflections of elements, provided that the minimum allowable length of the zone of bearing and anchorage of reinforcement.

Reliability-based load and resistance factors for soil-nail walls

2011 ◽  
Vol 48 (6) ◽  
pp. 915-930 ◽  
Author(s):  
G.L. Sivakumar Babu ◽  
Vikas Pratap Singh
Keyword(s):  
Limit Equilibrium ◽  
Limit State ◽  
Input Parameter ◽  
Limit States ◽  
Soil Nail ◽  
Resistance Factors ◽  
Strength Limit ◽  
Load And Resistance Factors ◽  
Load And Resistance Factor ◽  
Parameter Values

Existing soil nailing design methodologies are essentially based on limit equilibrium principles that together with a lumped factor of safety or a set of partial factors on the material parameters and loads account for uncertainties in design input parameter values. Recent trends in the development of design procedures for earth retaining structures are towards load and resistance factor design (LRFD). In the present study, a methodology for the use of LRFD in the context of soil-nail walls is proposed and a procedure to determine reliability-based load and resistance factors is illustrated for important strength limit states with reference to a 10 m high soil-nail wall. The need for separate partial factors for each limit state is highlighted, and the proposed factors are compared with those existing in the literature.

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