Expansion Joints

Damage of adjacent bridge structures due to relative responses, such as pounding and unseating, have been observed in many earthquakes. The isolators in bridge structures are effective in mitigating the induced seismic forces. However, the deck displacement becomes excessively large when subjected to ground motion with unexpected characteristics. This increases the possibility of pounding; and contributes to the unseating of bridge decks and subsequent collapse. An analytical model of expansion joints, that takes account of the interaction between adjacent bridge segments and the effect of impact and restrainers, is developed and nonlinear time history analyses are performed on a typical isolated multi-span bridge using three standard ground motions. The numerical simulation results show that pounding between adjacent bridge segments could amplify the relative displacement, resulting in the requirement of using an unseating prevention system. Restrainers are substantially effective in reducing the relative opening displacements and impact forces due to pounding at the expansion joints. However, the impact and the stretch of cable restrainers at expansion joints results in a large lateral force transfer from one deck to the other, which, consequently, significantly changes the global response of the participating structural systems. Therefore, it is effective to provide a shock absorber for the mitigation of impact effects between bridge segments or at the restrainers’ ends. The sudden changes of stiffness during poundings can be smoothed by using a natural rubber shock absorber, which prevents, to some extent, the acceleration peaks due to impact. The reaction forces at the pier bases and the pounding forces exerted on the superstructure can be satisfactorily reduced.

This patent describes an Apparatus for preventing temperature-induced tension failure of a tubing string of a producing subterranean well extending from a packer set in the well above a formation producing heated fluids to a fixed mounting at the well head, comprising: an expansion tool connectable in series relation with the tubing string; the expansion tool comprising two components slidably and sealably connected in telescopic relation; collet means on one component having radially biased locking heads; abutment means on the other component cooperable with the collet locking heads to secure the components in a telescopically contracted position; means responsive to a predetermined tension in the tubing string for releasing the securement of the components to permit expansion thereof to reduce tension in the tubing string; the predetermined tension approaching but being less than the tensile strength of the tubing string, the collet locking heads being reengageable with the abutme...

As pontes e viadutos são nomenclaturas pertencentes às OAEs e estruturas utilizadas para transpor o tráfego de veículos, pessoas e trens. Com o objetivo de vencer um vão, seja este composto por cursos d’água, no caso de pontes, ou composto por vales e depressões, neste caso viadutos. Assim como qualquer estrutura, as pontes e viadutos estão suscetíveis a sofrer muitas ações, como frenagens e acelerações, empuxo de terra, pressão d’água e variação de temperatura. Isto posto, para que estas ações sejam resistidas pelas pontes e viadutos, são designados elementos com o propósito de diminuir os impactos destas ações, e para amenizar os impactos de variação de temperatura são projetadas as juntas de dilatação.

As juntas de dilatação são elementos que não apresentam características estruturais, entretanto, são de grande importância para o funcionamento pleno de uma OAE. São posicionadas sobre os tabuleiros, e definem as transições entre eles. Devemos ressaltar que as juntas de dilatação, são elementos que estão posicionados na superfície dos tabuleiros, e grande parte dos tipos estão expostas as ações dos veículos, trens, pedestres e intemperismo.

Este trabalho final de graduação em Engenharia Civil, tem como foco demonstrar o início do uso de juntas de dilatação em pontes e viadutos, explicitar as características e aspectos dos principais tipos de juntas usuais. Sendo assim, iremos apresentar o desenvolvimento de inspeção de pontes e viadutos, com foco nas técnicas empregadas para a análise das juntas de dilatação e atribuindo estas técnicas as possíveis anomalias que possam apresentar. E por fim, buscaremos esclarecer as opções existentes para solucionar as possíveis patologias de forma exequível economicamente.

The pounding responses of the expansion joint in a curved ramp bridge under earthquake conditions. Long term effects of such seasonal temperature changes develop stresses and deformation in the building. Concrete creep and shrinkage increase the cracks widths and stresses. For elimination of this expansion joints are provided. The temperature expansion occurred most significantly during 20°C to 40°C and the optimised gradation could alleviate the arch expansion effectively, in the range of 20°C to 30°C. An expansion joint is a gap provided in the structure to allow expansion and contraction of the building due to temperature changes. It absorbs the heat-induced by expansion and contraction of various construction materials. Two theoretical models were used under eight types of seismic conditions. Results indicate that a curved ramp bridge without an abutment expansion joint is a favorable structure for seismic design.

Bridges are traditionally built with expansion joints at the ends to allow for longitudinal displacements of the superstructure due to temperature variations. Thus, most conventional bridges possess expansion joints and bearings, which are expensive in their materials and installation. Elimination of expansion joints in bridges may reduce the construction costs, overcome many of the maintenance problems, and increase the stability and durability of the bridges. These economic and functional advantages are generally recognized by bridge Engineers leading to the concept of integral construction or integral bridge. The lack of expansion joints in integral bridges results in reduced repair and maintenance costs throughout the service life of the bridge. It improves seismic resistance and extends long-term serviceability. The need to design bridges to withstand flood and debris loads has long been recognised however bridges are still failing to live their entire design life when subjected to extreme flooding events. This project presents a structural evaluation of bridges when subjected to the flood loadings that took place in Kerala , 2018. For this study, an existing conventional bridge is selected and flood analysis is carried out using SAP 2000. For the same site conditions, an integral bridge with equivalent cross section is analyzed, and results are compared.