scholarly journals Preliminary Design for Segmental Joint of Precast Tunnel Liner

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sirichai Pethrung ◽  
Supot Teachavorasinskun ◽  
Suraparb Keawsawasvong
Keyword(s):  
Reduction Factor ◽  
Design Calculation ◽  
Preliminary Design ◽  
Joint Opening ◽  
Design Procedures ◽  
Stiffness Reduction ◽  
Longitudinal Joint ◽  
Concrete Blocks ◽  
Joint Characteristic ◽  
External Forces

Abstract Responses of the segmental tunnel liner to external forces are primarily dependent on complicated interactions among construction process, soil structural interactions, segmental (longitudinal) joint characteristic etc. However, most proposed liner’s design procedures and recommendations are basically empirical and experience based, especially when the roles of tunnel joint are concerned. In the present study, a preliminary design calculation for the segmental joint with consideration of three practical conditions was proposed. The method adopts two main assumptions; the stiffness reduction factor and simplified pre-stressed concrete blocks, so that the flexural capacity of the segmental joint and its interactions to the main reinforced concrete segment body can be designated. Calculation examples are given for three most probable cases, namely, 1) the unbolted joint without joint opening, 2) the bolted joint without joint opening and 3) the unbolted segmental joint with allowing joint opening. Based on these calculations, the required compressive strength of concrete, thickness of liner, steel reinforcement, bolts and number of segments of the liner could be specified. The proposed method could well provide an engineer a tool to determine the initial joint configuration and its interaction to the overall tunnel lining.

An Approach to Determine the Stiffness Reduction Factor of Tunnel Lining

2011 ◽  
Vol 243-249 ◽  
pp. 3659-3662
Author(s):  
Hai Ying Zhou ◽  
Li Xin Li ◽  
Ting Guo Chen
Keyword(s):  
Numerical Analysis ◽  
Flexural Rigidity ◽  
Resistance Coefficient ◽  
Reduction Factor ◽  
Tunnel Lining ◽  
Soil Resistance ◽  
Stiffness Reduction ◽  
Simplified Method

Based on the segmental joint tests, it was found that the practical range of joint flexural rigidity was in range of 8500-29000kN•m/rad. A simplified method for determining the stiffness reduction factor of tunnel lining() was proposed using results from the segmental joint tests in which some parameters were obtained by calibration against a 3D Numerical analysis. The influence of joint flexural rigidity, soil resistance coefficient, thickness of tunnel lining and tunnel calculation radius on the stiffness reduction factor of tunnel lining was examined. The stiffness reduction factor can be simply expressed as a function of joint flexural rigidity ratio, soil resistance coefficient, thickness of tunnel lining and tunnel calculation radius for the typical tunnel lining.

Stiffness Reduction Factor for Flat Slab Structures under Lateral Loads

2009 ◽  
Vol 135 (6) ◽  
pp. 743-750 ◽  
Author(s):  
Sang-Whan Han ◽  
Young-Mi Park ◽  
Seong-Hoon Kee
Keyword(s):  
Reduction Factor ◽  
Lateral Loads ◽  
Flat Slab ◽  
Stiffness Reduction

The Application of Probability Theory to Model Updating

1997 ◽  
Author(s):  
Loukas Papadopoulos ◽  
Ephrahim Garcia
Keyword(s):  
Model Updating ◽  
Test Procedure ◽  
Simulated Data ◽  
Element Model ◽  
Reduction Factor ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Stiffness Reduction ◽  
Experimental Errors ◽  
Global Stiffness Matrix

Abstract A method is proposed for probabilistically model updating an initial deterministic finite element model using measured statistical changes in natural frequencies and mode shapes (i.e., modal parameters). The approach accounts for variations in the modal properties of a structure (due to experimental errors in the test procedure). A perturbation of the eigenvalue problem is performed to yield the relationship between the changes in eigenvalues and in the global stiffness matrix. This stiffness change is represented as a sum over every structural member by a product of a stiffness reduction factor and a stiffness submatrix. Monte Carlo simulations, in conjunction with the variations of the structural modal parameters, are used to determine the variations of the stiffness reduction factors. These values will subsequently be used to estimate statistics for the corrected stiffness parameters. The effectiveness of the proposed technique is illustrated using simulated data on an aluminum cantilever Euler-Bernoulli beam.

Preliminary Design Procedures for Equipment Exposed to Random Vibration Environments

2001 ◽  
Vol 44 (1) ◽  
pp. 23-27 ◽  
Author(s):  
Allan Piersol
Keyword(s):  
Random Vibration ◽  
Energy Analysis ◽  
Damping Ratio ◽  
Preliminary Design ◽  
Design Procedures ◽  
Long Duration ◽  
Final Design ◽  
Prediction Techniques ◽  
Maximum Stresses ◽  
Significant Resonance

A New NASA Handbook presents recommended procedures for the preliminary and final design of equipment items exposed to various dynamic loads, including random vibration excitations.1 For the final design when the geometric details of the equipment items have been largely determined, finite element method (FEM) and statistical energy analysis (SEA) procedures can be employed to predict the maximum stresses in equipment items due to random vibration excitations at their mounting points. In the preliminary design phase, however, more approximate prediction techniques are often needed, as summarized in the Handbook. The purpose of this paper is to detail the rationale behind these preliminary procedures. Included are simple techniques to predict a maximum instantaneous stress during a short duration vibration environment and fatigue damage during a long-duration vibration environment, based only upon estimates for the frequency and damping ratio of the first significant resonance of the equipment.

Pile group elastic load response prediction: friction piles embedded in cohesive soils

1984 ◽  
Vol 21 (3) ◽  
pp. 587-592
Author(s):  
R. A. Douglas ◽  
R. Butterfield
Keyword(s):  
Design Procedure ◽  
Pile Group ◽  
Response Prediction ◽  
Reduction Factor ◽  
Cohesive Soils ◽  
Pile Groups ◽  
Elastic Load ◽  
Stiffness Reduction ◽  
Load Response ◽  
Group Response

Predicting the elastic vertical working load response of friction pile groups embedded in cohesive soils is a problem still requiring a solution that can be easily implemented by practising engineers. A design procedure based on an extensive analysis of the results of a computer program is presented as a solution to the problem.The program was used to study the effects of the interaction of closely spaced piles in groups, on the pile group response to loading. It is possible to define an average pile stiffness (load per unit displacement) and discuss a reduction of this stiffness, due to pile interaction, when the pile is placed in a group of similar piles. This interaction is accounted for by a stiffness reduction factor, ρ.The design approach is compared with load tests at model and full scale, with good agreement. Key words: piles, pile groups, working loads, elastic pile displacements.

Study on Flexural Stiffness Reduction Factor of Reinforced Concrete Column with Equiaxial T Shaped Section

2013 ◽  
Vol 351-352 ◽  
pp. 319-324
Author(s):  
Xiu Ling Feng ◽  
Meng Shen ◽  
Xiang Ya Kong ◽  
Jie Zhang ◽  
Peng Fei Luo
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structure ◽  
Geometrical Nonlinearity ◽  
The United States ◽  
Reduction Factor ◽  
Material Nonlinearity ◽  
Flexural Stiffness ◽  
Stiffness Reduction ◽  
Stiffness Method ◽  
Shaped Section

The reduced stiffness method had been adopted to evaluate the material nonlinearity characteristics of reinforced concrete structures to be in compliance with concrete structure standards of the United States, New Zealand and Canada. Concrete structure design code in China also accepts the reduced stiffness method as a supplementary method of considering the second-order effects problem. However, the concrete structure with specially shaped columns code of China still use amplified coefficients of eccentricity to consider nonlinearity characteristics of reinforced concrete structure with special shaped columns. Based on the numerical integral method, a flexural stiffness reduction factor is proposed to consider characteristics of material nonlinearity and geometrical nonlinearity of reinforced concrete columns with equiaxial T shaped section.

scholarly journals Research on Damage Identification of Grid Structure Based on Genetic Algorithm

2019 ◽  
Vol 136 ◽  
pp. 03014
Author(s):  
Yu Wang ◽  
Menghong Wang ◽  
Huan Lu
Keyword(s):  
Numerical Simulation ◽  
Genetic Algorithm ◽  
Damage Identification ◽  
Simulation Analysis ◽  
Fitness Function ◽  
Reduction Factor ◽  
Grid Structure ◽  
Identification Method ◽  
Stiffness Reduction ◽  
Mutation Operators

This paper proposes a genetic algorithm based damage identification method for grid structures. The genetic algorithm is used to process the modal information of the structure, and the damage identification of the truss structure is carried out. The stiffness reduction factor of the structural member is used as the optimization variable. The objective function is constructed according to the frequency and vibration mode, and the fitness function is established. The binary coding method is used to improve the crossover and mutation operators. In this paper, a grid structure model is used for numerical simulation analysis and verified by experiments. In the experimental stage, the grid structure is excited by hammering method, and the response data of each node and the modal information of the structure are obtained. Numerical simulation and experimental analysis show that the damage identification method based on genetic algorithm can effectively judge the location and extent of damage.

Sign in / Sign up

Export Citation Format

Share Document