Parametric study on dynamic interaction of horizontally curved twin I-girder bridges and a moving vehicle

Behavior of horizontally curved I-girder bridges are complex and its interaction analysis is difficult. In this study, extended three-dimensional finite element interaction analyses were conducted parametrically. The bridge is modeled in detailed with solid and shell elements and vehicle is simulated as a nonlinear model according to HS20-44 design truck. Road roughness profiles are generated from power spectral density and cross spectral functions. By using these models, natural vibration and forced vibration analyses carried out in parametric study, are extensively investigated. The analytical results are significant and give some useful information regarding the impact factor of the studied bridge which could be much helpful for practical designer

A finite element analysis of bearing resistence of timber loaded through a steel plate

Decrease projected length of bolts due to bending deformation in timber joints compresses the steel washers onto timber member and increases lateral resistance of the joints. As this lateral strength increase primarily depend on bearing characteristics of timber beneath the steel washers, a finite element analysis was performed to predict their bearing-embedment behavior. A 3-D finite element model consisting of 8-node solid and contact pair elements was developed using ANSYS assuming an anisotropic plasticity model for timber and an elastic-perfectly plastic model for the washers. Material constants for both steel washer and timber member were obtained from previous test data. The results of the analysis were in good agreement with the experimental load-embedment curves as well as the analytical curves obtained in a previous study based on a rigid-body-spring-model. The same approach was also used to evaluate the effective bearing length (under uniform compression) of a 50 mm depth timber block partially compressed

Seismic Shear Forces in Shear Walls of a Medium-Rise Building Designed by Response Spectrum Analysis

According to ASCE7-05, response spectrum analysis (RSA) procedure can be used to determine the seismic demands of the structures for the seismic design of any type of structures. However, this design procedure has been found to be inappropriate for medium-rise and high-rise buildings. This paper is aimed at verifying the RSA procedure prescribed in the current Thai seismic design code which is based on ASCE7-05 and proposing appropriate modification to the design shear force from RSA procedure. A 16-story medium-rise reinforced-concrete core-wall case-study building was first designed based on RSA procedure and then the non-linear response history analysis (NLRHA) was performed to determine the more accurate seismic demands of the structure. The results show that seismic shear demand of the shear wall from non-linear analysis is about 2 times the shear capacity of the wall designed by RSA procedure. This could lead to shear failure in the shear walls designed by RSA procedure. To avoid shear failure in the shear wall elements, the shear demands in the wall elements designed by RSA procedure needs to be amplified by a factor of 2, which is equivalent to reducing the response modification factor R = 5.5 in ASCE7-05 to R = 2.75 (for shear force in the shear wall only)

Key aspects in the analysis and design of Hyperloop(TM) infrastructure under static, dynamic and thermal loads

[EN] Hyperloop is an avant-garde idea for high-speed transportation of passengers and freight in a \emph{pod} or capsule-like vehicle travelling through an hermetically sealed tube with reduced internal pressure. Its maximum envisaged speed is around \SI{1200}{\kmh}, which would be directly comparable to airplane travel and much faster than road and railway transportation. Because the unconventional, ad-hoc civil infrastructure required for Hyperloop is still under a conceptual design phase, one of the most important steps to undertake at this stage is to develop analytical models and tools to simulate the mechanical behaviour, so that any potential issue can be anticipated. This article is a novel comprehensive study of the relevant phenomena that influence the design of Hyperloop infrastructure from the structural engineering viewpoint. The aim is to obtain, for the first time, representative values of the main internal forces and stresses leading to a preliminary design of the vacuum tube and, simultaneously, to provide relevant insight into the main phenomena involved. Depending on the longitudinal restrictions implemented at the piers, two basic configurations based on steel tubes are proposed. The strength and stability of the tube have been analysed thoroughly by taking into account the self and dead weight, internal low pressure, wind, thermal and traversing vehicle dynamic effects. Fatigue has also been assessed at potential critical locations. The relevance of each external action has been suitably highlighted, with particular emphasis on the predominant thermal and buckling effects. Estimates of the required tube thickness are provided, and resonance phenomena at some particular speeds are pointed out. Since the Hyperloop concept comprises both vehicle design and structure standardization that strongly relate to each other, their definition must be advanced in parallel. This work represents a starting point for future detailed studies, as the HL technology evolves through subsequent stages when relevant details of vehicle design will be available.The authors gratefully acknowledge the financial support of the Generalitat Valenciana, through grant AICO/2019/025 for the project "Analisis Dinamico aplicado al Diseno de Viaductos para Hyperloop: Vibraciones de Flexion, Torsion y Limites Normativos", within research funding program AICO2019: Subvenciones para grupos de investigacion consolidables.Museros Romero, P.; Lazaro, C.; Pinazo, B.; Monleón Cremades, S. (2021). Key aspects in the analysis and design of Hyperloop(TM) infrastructure under static, dynamic and thermal loads. Engineering Structures. 239:1-20. https://doi.org/10.1016/j.engstruct.2021.112177S12023

Neural network modelling of RC deep beam shear strength

YesA 9 x 18 x 1 feed-forward neural network (NN) model trained using a resilient back-propagation algorithm and early stopping technique is constructed to predict the shear strength of deep reinforced concrete beams. The input layer covering geometrical and material properties of deep beams has nine neurons, and the corresponding output is the shear strength. Training, validation and testing of the developed neural network have been achieved using a comprehensive database compiled from 362 simple and 71 continuous deep beam specimens. The shear strength predictions of deep beams obtained from the developed NN are in better agreement with test results than those determined from strut-and-tie models. The mean and standard deviation of the ratio between predicted capacities using the NN and measured shear capacities are 1.028 and 0.154, respectively, for simple deep beams, and 1.0 and 0.122, respectively, for continuous deep beams. In addition, the trends ascertained from parametric study using the developed NN have a consistent agreement with those observed in other experimental and analytical investigations

MITIGATION MEASURES FOR EXPANSION JOINT EFFECTS ON SEISMIC PERFORMANCE OF BRIDGE STRUCTURES

The Thirteenth East Asia-Pacific Conference on Structural Engineering and Construction (EASEC-13), September 11-13, 2013, Sapporo, Japan

SEISMIC RESPONSE OF CURVED GRILLAGE GIRDER VIADUCTS WITH BASE ISOLATION SYSTEM IN COLD REGION

The Thirteenth East Asia-Pacific Conference on Structural Engineering and Construction (EASEC-13), September 11-13, 2013, Sapporo, Japan

Bearing properties of Shorea obtusa beneath a laterally loaded bolt

Empirical equations to determine the bearing strength have been proposed by many researchers and design standards. Because these equations have been developed mainly based on test results of softwood species, it is a matter of great importance (to ASEAN structural engineers) to verify the applicability of these equations for tropical hardwood species, which are commonly used in many ASEAN countries. In this study, wood specimens of Shorea obtusa (a tropical hardwood species) were used and the bearing test under full-hole confi guration was carried out for fi ve different loading angles to the grain. The bearing stress-embedment curve obtained from the test was approximated by a linear elastic-plastic diagram indicating the initial and fi nal stiffness of the curve. Testing showed that the average bearing strength parallel to the grain was 7.25% lower than the prediction given in Eurocode 5. The bearing strength perpendicular to the grain evaluated based on bearing load at initial cracking was substantially different from any predictions given by previous studies or design standards. It was also found that the bearing strength and initial stiffness from the bearing stress-embedment curve for loading at intermediate angles to the grain could be satisfactorily predicted with Hankinson’s formula