scholarly journals Numerical Analysis of Twin Tunnels Lining under Different Seismic Conditions

2021 ◽  
Vol 6 (2) ◽  
pp. 29
Author(s):  
Abdelhay El Omari ◽  
Mimoun Chourak ◽  
El Mehdi Echebba ◽  
Seif-Eddine Cherif ◽  
Carlos Navarro Ugena ◽  
...  
Keyword(s):  
Cross Sections ◽  
Bending Moment ◽  
Relative Displacement ◽  
Tunnel Lining ◽  
Seismic Signals ◽  
Rock Bolts ◽  
The Usa ◽  
Al Hoceima ◽  
Support Devices ◽  
Twin Tunnels

The last seismic events showed that tunnel lining may suffer extensive damage. Employing numerical modeling has a great importance in predicting the seismic performance of tunnels. This paper tests the tunnel lining of the Zaouit Ait Mellal (ZAM) twin tunnels located between the cities of Marrakesh and Agadir in Morocco. Dynamic analysis was adopted by FLAC 2D software using the finite-difference elements. Four soil cross-sections were chosen, with different support devices installed along the twin tunnels, such as rock bolts and steel ribs. The seismic signals introduced as input were obtained from three different earthquakes: Al Hoceima 2004 in Morocco, EL Centro 1940 in the USA, and Kobe 1995 in Japan. The numerical results show that the deformation of the tunnel lining is more noteworthy in the sections using steel ribs compared to those using rock bolts, which is observed by the large values of relative displacement, reaching 1020 (mm) and 2.29 × 105 (N.m/m) of maximum bending moment. The analysis indicates that these sections present higher vulnerability during an earthquake, which should be considered when looking at the overall safety of the tunnel.

scholarly journals THE LIMIT STATE DESIGN OF SPUN CONCRETE COLUMNS USING LOAD COMBINATIONS RECOMMENDED BY EN 1990 AND ASCE/SEI 7–05

2009 ◽  
Vol 15 (3) ◽  
pp. 289-297 ◽  
Author(s):  
Antanas Kudzys ◽  
Romualdas Kliukas
Keyword(s):  
Cross Sections ◽  
Limit State ◽  
Bending Moment ◽  
High Strength ◽  
Concrete Columns ◽  
Test Material ◽  
Resistance Factors ◽  
The Usa ◽  
Load And Resistance Factors ◽  
Spun Concrete

The expediency of using precast spun concrete columns of annular cross‐sections reinforced by high‐strength steel bars is discussed. Test material properties, efficiency factors and resisting compressive stresses of plain and reinforced spun concretes are presented. Modelling a bearing capacity of eccentrically loaded members of annular cross‐sections is based on the concepts of compression with a bending moment and bending with a concentrical force. The comparison of test and modelling data of concentrically and eccentrically loaded members is analysed. The expediency to use in design practice the approaches of current methods of partial safety factors design (PSFD) legitimated in Europe and load and resistance factors design (LRFD) suggested in the USA and other countries is considered and illustrated by a numerical example. Santrauka Aptariamas didžiastiprio plieno strypais armuotų žiedinio skerspjūvio centrifuguotojo betono kolonų naudotinumas. Pateiktos armuotojo ir nearmuotojo centrifuguotojo betono medžiagų savybės, efektyvumo veiksniai ir laikomieji gniuždymo įtempiai. Ekscentriškai gniuždomų žiedinio skerspjūvio elementų laikomajai galiai modeliuoti taikomos lenkiamojo gniuždymo ir gniuždomojo lenkimo sampratos. Analizuojamas centriškai ir ekscentriškai apkrautų elementų eksperimentinių ir modeliavimo duomenų sugretinimas, nagrinėjamas Europos, JAV ir kitų šalių projektavimo praktikoje įteisintų ir paplitusių dalinių veiksnių ir apkrovų bei atsparių veiksnių metodų taikymo tikslingumas, kurį rodo skaitmeninis pavyzdys.

scholarly journals Transient Response of Bridge Piers to Structure Separation under Near-Fault Vertical Earthquake

2021 ◽  
Vol 11 (9) ◽  
pp. 4068
Author(s):  
Wenjun An ◽  
Guquan Song
Keyword(s):  
Large Scale ◽  
Bending Moment ◽  
Relative Displacement ◽  
Superposition Method ◽  
Longitudinal Displacement ◽  
Transient Wave ◽  
Vibration Period ◽  
Vertical Excitation ◽  
Mode Superposition Method ◽  
Main Girder

Given the possible separation problem caused by the double-span continuous beam bridge under the action of the vertical earthquake, considering the wave effect, the transient wave characteristic function method and the indirect mode superposition method are used to solve the response theory of the bridge structure during the earthquake. Through the example analysis, the pier bending moment changes under different vertical excitation periods and excitation amplitudes are calculated. Calculations prove that: (1) When the seismic excitation period is close to the vertical natural vibration period of the bridge, the main girder and the bridge pier may be separated; (2) When the pier has a high height, the separation has a more significant impact on the longitudinal displacement of the bridge, but the maximum relative displacement caused by the separation is random; (3) Large-scale vertical excitation will increase the number of partitions of the structure, and at the same time increase the vertical collision force between the main girder and the pier, but the effect on the longitudinal displacement of the form is uncertain; (4) When V/H exceeds a specific value, the pier will not only be damaged by bending, but will also be damaged by axial compression.

Closed-form moment-curvature relations for reinforced concrete cross sections under bending moment and axial force

2016 ◽  
Vol 129 ◽  
pp. 67-80 ◽  
Author(s):  
Pedro Dias Simão ◽  
Helena Barros ◽  
Carla Costa Ferreira ◽  
Tatiana Marques
Keyword(s):  
Reinforced Concrete ◽  
Closed Form ◽  
Axial Force ◽  
Cross Sections ◽  
Bending Moment

The Behavior of Long Beams Under Impact Loading

1950 ◽  
Vol 17 (1) ◽  
pp. 27-34
Author(s):  
P. E. Duwez ◽  
D. S. Clark ◽  
H. F. Bohnenblust
Keyword(s):  
Plastic Deformation ◽  
Cross Sections ◽  
Constant Velocity ◽  
Bending Moment ◽  
Infinite Length ◽  
Longitudinal Impact ◽  
Deflection Curve ◽  
Transverse Impact ◽  
Cold Rolled ◽  
Annealed Copper

Abstract This paper presents the results of a theoretical and experimental investigation of the plastic deformation of long beams which are subjected to a concentrated transverse impact of constant velocity. In the theoretical analysis, the beam is supposed to be of infinite length, and plane cross sections are assumed to remain plane. The bending moment is assumed to depend on the curvature according to a function that is obtained from the stress-strain curve of the material. The theory neglects both the lateral displacement of the cross sections against each other due to the shearing force and the rotary kinetic energy of the motion of the beam. The theory shows that a strain is not propagated along a beam at constant velocity, as in the case of longitudinal impact. The strain depends on the ratio between the square of the distance from the point of impact and the time. This is correct regardless of the shape of the moment - curvature curve. If certain approximations are applied to the bending moment - curvature curve, the theory provides a method of computing the deflection curve of a beam at any instant during impact. An experimental study has been made in which the deflection curves of long simply supported beams have been obtained during impact. The deflection characteristics of a cold-rolled steel and an annealed-copper beam have been computed by approximating the bending moment - curvature curves. It is shown that for materials such as cold-rolled low-carbon steel, for which plastic deflection is localized at the point of impact, the observed deflection curve is closely approximated by computing a curve based on the assumption that the beam remains elastic. For a soft material like annealed copper, plastic deformation extends over a relatively large distance from the point of impact and, taking plastic deformation into account, a satisfactory agreement is obtained between theory and experimental results.

STIFFNESS OF REINFORCED CONCRETE STRUCTURES UNDER BENDING WITH TRANSVERSE AND LONGITUDINAL FORCES

2021 ◽  
Vol 98 (6) ◽  
pp. 5-19
Author(s):  
VL.I. KOLCHUNOV ◽  
◽  
O.I. AL-HASHIMI ◽  
M.V. PROTCHENKO ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Cross Sections ◽  
Concrete Structures ◽  
Bending Moment ◽  
Reinforced Concrete Structures ◽  
The Matrix ◽  
Local Shear ◽  
The Difference ◽  
Inclined Cracks ◽  
Opening Width

The authors developed a model for single reinforced concrete strips in block wedge and arches between inclined cracks and approximated rectangular cross-sections using small squares in matrix elements. From the analysis of the works of N.I. Karpenko and S.N. Karpenko the "nagel" forces in the longitudinal tensile reinforcement and crack slip , as a function of the opening width and concrete deformations in relation to the cosine of the angle . The experimental " nagel " forces and crack slip dependences for the connection between and in the form of an exponent for the reinforcement deformations and spacing are determined. The forces have been calculated for two to three cross-sections (single composite strips) of reinforced concrete structures. On the bases of accepted hypothesis, a new effect of reinforced concrete and a joint modulus in a strip of composite single local shear zone for the difference of mean relative linear and angular deformations of mutual displacements of concrete (or reinforcement) are developed. The hypothesis allows one to reduce the order of the system of differential equations of Rzhanitsyn and to obtain in each joint the total angular deformations of concrete and the "nagel" effect of reinforcement. The curvature of the composite bars has a relationship from the total bending moment of the bars to the sum of the rigidities. The stiffness physical characteristics of the matrix from the compressed concrete area and the working reinforcement are obtained in a system of equations of equilibrium and deformation, as well as physical equations.

A shear center demonstration model using 3D-printing

2021 ◽  
pp. 030641902110574
Author(s):  
Lawrence N Virgin
Keyword(s):  
3D Printing ◽  
Cross Section ◽  
Cross Sections ◽  
Principal Axis ◽  
Practical Importance ◽  
Bending Moment ◽  
Shear Center ◽  
Cross Sectional ◽  
Thin Walls ◽  
Section Profile

Locating the shear, or flexural, center of non-symmetric cross-sectional beams is a key element in the teaching of structural mechanics. That is, establishing the point on the plane of the cross-section where an applied load, generating a bending moment about a principal axis, results in uni-directional deflection, and no twisting. For example, in aerospace structures it is particularly important to assess the propensity of an airfoil section profile to resist bending and torsion under the action of aerodynamic forces. Cross-sections made of thin-walls, whether of open or closed form are of special practical importance and form the basis of the material in this paper. The advent of 3D-printing allows the development of tactile demonstration models based on non-trivial geometry and direct observation.

The Torsionless Bending of a Hollow Beam by a Transverse Load

1937 ◽  
Vol 4 (1) ◽  
pp. A25-A30
Author(s):  
W. L. Schwalbe
Keyword(s):  
Cross Sections ◽  
Equilateral Triangle ◽  
Bending Moment ◽  
Longitudinal Section ◽  
Transverse Load ◽  
Shearing Stress ◽  
Numerical Work ◽  
Hollow Beam ◽  
Transverse Loads ◽  
Hollow Beams

Abstract The author discusses the bending of hollow beams when subjected to transverse loads, and points out that shearing stresses and strains in the cross sections are necessary, and a particular longitudinal section remains plane only if the resultant of the shearing stress, and hence the plane of the applied bending moment, possesses a particular location. The author determines the location of this resultant shearing stress by applying a method based on St. Venant’s theory. Applications of the method are made to two hollow sections. One of the sections is that of an equilateral triangle which serves as a measure of accuracy for the numerical work presented by the author, since the location of the resultant of the shearing stresses is known by symmetry.

scholarly journals Synthesis of numerical methods for the design of segmental tunnel lining

2019 ◽  
Vol 295 ◽  
pp. 03008
Author(s):  
Rim Trad ◽  
Hussein Mroueh ◽  
Hanbing Bian ◽  
Fabrice Cormery
Keyword(s):  
Numerical Study ◽  
Direct Method ◽  
Bending Moment ◽  
Experimental Methods ◽  
Tunnel Lining ◽  
Practical Case ◽  
Lining Structure ◽  
Water Conveyance ◽  
Internal Forces ◽  
Water Conveyance Tunnel

This paper presents a numerical study that aims to compare the behavior of the segmental tunnel lining using the direct, indirect and experimental methods. This model is based on a practical case applied in university of Tongji: a project of water conveyance tunnel. A reduction in the bending moment and increasing of the displacement in the tunnel lining is showed in numerical results, when taking into account the effect of the joints. It has been shown that the number of joints in the tunnel-lining structure highly affects the results in terms internal forces and displacements. Furthermore, the internal forces obtained by the continuous method are high compared to the other methods when the effects on segmental joints on tunnel lining behaviour are usually considered. Additionally, the bending moment of the direct method with behaviour of rotation spring linear and experimental method is comparable.

Performance of RC Precast Continuous Beams Incorporating New Strategy for Design and Allocating Connections

2020 ◽  
Vol 20 (06) ◽  
pp. 2040006
Author(s):  
Yingwu Zhou ◽  
Wenlong He ◽  
Biao Hu ◽  
Zhiheng Hu
Keyword(s):  
Bearing Capacity ◽  
Cross Sections ◽  
Bending Moment ◽  
Concrete Specimen ◽  
Steel Plates ◽  
Weak Point ◽  
Cross Section Area ◽  
New Strategy ◽  
Joint Connection ◽  
Column Joint

The performance of joint connections has always been the key to precast assembly structures. This paper proposes a new type of joint connection that is made by means of pre-embedded steel plates and connected by bolts or welding without any wet work. Located outside the beam-column joint, the connection is arranged around the inflection point of the beam where the bending moment is small. Three precast beams of different cross-sections and a set of cast-in-place concrete contrast beams were prepared and loaded by the anti-symmetric static loading method. The results show that the joint connection changes the failure mode of the specimens, transfers the failure section from the weak point to the non-weak point, and improves the bearing capacity of the specimens. With the increase of the cross-section area of the embedded steel plate at the joint, the bearing capacity and the ductility of the specimens increase. The energy consumption capacity of the precast specimen is significantly higher than that of the ordinary cast-in-place concrete specimen. Since the joint has not been destroyed, the component can be replaced when other parts of the specimen are destroyed.

Analysis of Permanent Lining of Branisko Tunnel

2017 ◽  
Vol 738 ◽  
pp. 249-260
Author(s):  
Jana Chabronova ◽  
Marek Bednar ◽  
Jan Snopko
Keyword(s):  
Static Analysis ◽  
Cross Sections ◽  
Measured Data ◽  
Tunnel Lining ◽  
Concrete Lining ◽  
Loading Conditions ◽  
Size And Shape ◽  
Geotechnical Monitoring ◽  
Operational Life ◽  
Real State

Structural layouts of the tunnel concrete linings are dictated by various factors; to name the most influential ones: geology and hydrological conditions, overburden depth, size and shape of the tunnel and the method of excavation and support. Varying tunnel lining thicknesses and loading conditions, imposed by the above factors, require multiple computations to represent typical and critical cross sections and which are relevant for the structural designs. In contrast to the temporary (primary) lining, where some failures of the lining can be tolerated and may be used in the lining design, a permanent concrete lining has to be designed for a maintenance-free life of 50 or more years. Consequently, all the loads that may occur during the operational life of the tunnel have to be taken into account. This article deals with analysis of the geotechnical monitoring results from the Branisko tunnel which was carried out during 2003 – 2013. One part of geotechnical monitoring was checking of cracks which were created during construction of the permanent lining. Measured data are utilized for comparison of static calculations of the supposed load cases of permanent lining with real state of stresses. The static analysis has been performed in two different models developed for different static patterns.

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