Published online in January 2018
Abstract: Cables are efficient structural elements that are used in cable-stayed bridges, suspension bridges and other cable structures. These cables are subjected to environmental excitations such as rain- wind induced vibrations. Rain-wind induced stay-cable vibrations may occur at different cable eigenfrequencies. Several methods, including aerodynamic or structural means, have been investigated in order to control the vibrations of bridge’s stay-cables. Aerodynamic methods, such as modification of the cable roughness were effective only for certain types of vibration. Another method is the coupling of the stays with secondary wires, in order to reduce their effective length and thereby to avoid resonance. Finally, external transverse dampers have to be designed for several target cable modes in order to decrease the oscillations amplitude and to damping them. This paper investigates a movable anchorage system with a Classical Rolling Pendulum Bearing (CRPB) device. An analytical model of cable-damper system is developed herein based on the taut string representation of the cable. The gathered integral-differential equations are solved through the use of the Lagrange transformation. Finally, a case study with realistic geometrical parameters is also presented to establish the validity of the proposed system.
International Journal of Bridge Engineering, Vol. 5, No. 3, 2017: pp. 1-23
Abstract: The mechanical behavior and failure mechanism of stone arch rib enclosed by reinforced concrete under different existed stress level is obtained by the three group failure tests of pressed members enclosed by reinforced concrete. The effect of the cross-section load capacity with different stress states is studied by test results. Then an analytical method considering the influence factors is proposed to count cross-section load capacity of stone arch rib enclosed by reinforced concrete.
International Journal of Bridge Engineering, Vol. 5, No. 3, 2017: pp. 25-30
Yi Mao, Jeffrey A. Laman
Abstract: During rainy seasons, rural communities around the world become isolated from health care, education and other essential services due to flooding. Pedestrian suspension bridges are built to provide these communities with access to their basic needs. However, dynamic response problems may occur due to low stiffness, low mass and low damping of these bridges. The present study utilized a scaled, physical suspension bridge model to obtain dynamic response data that was in turn utilized to develop and calibrate a numerical bridge modeling methodology. The calibrated modeling methodology was employed to complete several dynamic analysis simulations under more complex load cases and combinations than have previously been studied. Simulations in the present study include seventeen pedestrian load combinations, one animal load combination and one handcart load combination. In addition, an investigation into the influence of a bystander on bridge dynamic response was conducted through modeling a human bystander. The present study observed that the peak response induced by a jogger is twice the response of a walker, while a bicycle induces a 77 percent smaller response than the walker. The most critical combination for two pedestrians occurs when they enter the bridge together at the same time and maintain the same pace. It was also observed that the existence of a bystander decreases the vertical response near the bystander location while the lateral response is minimally affected.
International Journal of Bridge Engineering, Vol. 5, No. 3, 2017: pp. 31-52
Ioannis G. Raftoyiannis, George T. Michaltsos
Abstract: This paper deals with the influence of a moving mass-load on the eigenfrequencies of a single span bridge as well as its dynamic deformations taking into account the above altered eigenfrequencies that are constantly changing due to the mass-load movement. A simple but efficient 2-DOF model is considered in order to study the dynamic behavior of the bridge, while the theoretical formulation is based on the modal superposition approach and the continuum approach, which has been widely used in the bibliography to analyze such problems. The resulting non-linear differential system of equations of motion is solved with the aid of a commercial symbolic manipulator and useful results are gathered and presented in graphical and tabular form.
International Journal of Bridge Engineering, Vol. 5, No. 3, 2017: pp. 53-68
Benazir F. Ahmed, Kaustubh Dasgupta
Abstract: The seismic assessment of bridges has been on ever-increasing demand owing to the crippling consequences of earthquakes on the integrity of the transportation networks of which the bridges are the most sensitive elements. It has been widely accepted that a priori assessment of vulnerability of a bridge to seismic damage helps towards critical pre-earthquake safety decisions regarding replacement or setting up appropriate retrofit strategy for the bridge with an objective of minimizing life and socio-economic losses during future earthquakes. This paper reviews the past studies on vulnerability assessment of various existing bridge types and configurations through the generation of analytical fragility curves and summarizes the various steps involved in different methodologies. Generation of fragility function is one of the key components of seismic vulnerability assessment. Past studies reveal that realistic fragility estimates are obtained through detailed analysis of bridge-foundation-soil system, reliable definition and quantification of damage states and identification of an optimal earthquake intensity measure corresponding to the particular bridge structural configuration and site-specific earthquake hazard.
International Journal of Bridge Engineering, Vol. 5, No. 3, 2017: pp. 69-122
William Z Li
Abstract:The conventional bridge design consists of some type of superstructure resting on an abutment at each end. There may also be one or more intermediate piers as middle supports. This will heavily rely on the expansion joint/bearing for abutments movement, and joint/bearing can be a significant post-construction maintenance issue and increased cost during the life circle of a bridge. Therefore, a new concept was developed to physically and structurally connect the superstructure and abutments to create what is referred to as an integral-abutment bridge (IAB). With this solution, the highly maintenance and costly expansion joint/bearing is eliminated. However, within the construction period, quality control to ensure the end product compliance with standard and design is challenging especially unforeseen river condition will always drive the construction team toward unfavorable outcome and rectification/innovated solutions in this paper provide a case study in Australia for interested researcher and engineer as reference.
International Journal of Bridge Engineering, Vol. 5, No. 3, 2017: pp. 123-131
Ioannis N. Tsiptsis, Evangelos J. Sapountzakis
Abstract:Towards improving conventional beam elements in order to include nonuniform warping effects in the dynamic analysis of bridge decks, in this paper, independent warping parameters have been taken into account and advanced stiffness matrices have been proposed. In addition to this, curved beam’s behavior becomes more complex, even for dead loading, due to the coupling between axial force, bending moments and torque that curvature produces. Thus, the importance of simulating geometry exactly arises in order to approximate accurately the response of the curved beam. For this purpose, the Isogeometric tools (b-splines and NURBS), either integrated in the Finite Element Method (FEM) or in a Boundary Element based Method (BEM) called Analog Equation Method (AEM), are employed in this contribution for the static and dynamic analysis of horizontally curved bridge decks of open (I girders) or closed (box-shaped) cross section. Free vibration characteristics and responses of the stress resultants and displacements to static, moving and earthquake loading have been studied. Design guidelines for intermediate diaphragms have been applied for different thin-walled box-shaped bridge decks and assessed as an indirect way to prevent distortional effects.
International Journal of Bridge Engineering, Vol. 5, No. 3, 2017: pp. 133-182