Search

This paper introduces a novel pocket‐type dissipative rocking connection for self‐centering tubular steel bridge piers. Unlike typical self‐centering systems, this connection does not utilize post‐tensioned tendons and relies solely on gravity load for re‐centering, but it employs a redundant mechanism to prevent geometrical instability and collapse. The connection consists of several components, including an embedded sleeve component and a ring plate bearing against the column and frictionally connected to the embedded component. During rocking, the ring plate provides two‐level energy dissipation through friction and material yielding. In this connection, any residual drift could be easily recovered by untightening bolts in the frictional connection of the ring plate. A finite element model with contact elements at surface interfaces between different components was developed to simulate the response of the connection under vertical and lateral loading. Finite element analyses and quasi‐static cyclic tests of a quarter‐scale specimen demonstrated that the connection could provide adequate lateral resistance and a flag‐shaped hysteresis response with marginal or recoverable residual displacements. Test results confirmed that the connection can sustain large lateral drifts (up to 7.6%) without structural damage. Test results also indicated that the hysteresis characteristics of the connection are highly influenced by the type and configuration of the washers in the bolt assembly of the frictional connection. The lateral strength and energy dissipation properties of the connection were greatly improved when conical spring washers were added to the bolt assembly. [ABSTRACT FROM AUTHOR]

This paper presents a novel rocking system for bridge piers that aims to minimize structural damage and reduce residual drift during seismic events. This system relies on gravity for re-centering and does not utilize post-tensioned tendons. It consists of a pair of tubular steel columns attached to the foundation and cap beam with rocking connections. Each connection utilizes a friction damper that absorbs energy through friction at low lateral displacement and plastic deformation at large lateral displacement. Finite element (FE) simulation was utilized to evaluate the behavior of this system under vertical and lateral loading. The finite element models under two different gravity loads were subjected to lateral cyclic loading to study the re-centering characteristics of the system. The analyses have demonstrated that the system exhibits a flag-shaped hysteresis response with minimal residual drift. A supplementary analysis has also shown that any residual drift in this system can be recovered by loosening bolts in the frictional connection [ABSTRACT FROM AUTHOR]

Natural gas transmission pipelines are at risk of failure when they traverse potential landslide regions, leading to significant service disruptions and environmental impacts. This paper presents the results of an analytical study on the vulnerability of typical natural gas transmission pipelines when they are subjected to landslide-induced ground displacements. Pipeline vulnerability was evaluated for four pipe diameters under different internal pressures and various ground displacement profiles. The effects of pipe wall thickness and steel grade on vulnerability were also evaluated. The finite-element method was used to model the pipelines and the surrounding soils. Nonlinear static analyses were carried out to evaluate the response of the pipelines under landslide-induced ground displacements. Based on results of the analyses, landslide fragility functions were developed for the pipelines at the pressure integrity (PI) limit state. The results of this study indicate that pipeline vulnerability decreases with increasing pipe diameter but increases with increasing landslide width up to a threshold width where the effect becomes negligible. Additionally, internal pressure is found to have no significant effect on the vulnerability of various pipelines at the PI limit state. The results also show that the risk of pipeline failure can be reduced significantly by increasing pipe wall thickness and using a higher grade of steel material in landslide regions. [ABSTRACT FROM AUTHOR]

The study aimed to evaluate the behavior of typical natural gas transmission pipelines in landslides and investigate the effect of various parameters such as internal pressure, pipe diameter, and soil type on their active lengths. Nonlinear Finite Element Analyses (FEA) were performed using the Winkler-type beam-on-spring model to evaluate the pipeline response in landslides. The FEA results showed that the stress and strain distribution along the pipeline were primarily positive, which indicated that the ground movement was resisted by axial tension force (membrane action) of the pipeline. The maximum axial strain occurred at the beginning and the end of the landslide zone, indicating that the pipeline would fail at these locations. The FEA results also indicated that the maximum axial forces in all cases were very close to the section capacity of the pipe, indicating that landslide-induced ground displacements resulted in very high axial force and relatively low bending moment in typical natural gas transmission pipelines. The PRCI guidelines provide an equation for estimating the anchor length of buried steel pipelines, but the results of this study indicate that the anchor lengths are much larger than those calculated by the PRCI equation. A proposed equation based on ultimate strength of the pipe section is suggested for calculating anchor length, which gives a good estimate of the anchor length with an average error of 4% relative to the analytical results. Overall, the study concluded that the internal pressure of the pipeline had no significant effect on the anchor lengths of the pipelines, and the proposed equation provides a more accurate estimate of the anchor length of typical natural gas transmission pipelines. [ABSTRACT FROM AUTHOR]

Concrete anchor blocks are usually used to restrain the axial expansion of natural gas transmission pipelines near compressor stations. Current design procedures for the anchor blocks are based on providing an adequate margin of safety against block sliding, block overturning and soil bearing pressure. This paper presents the results of an analytical study on the response of soil, pipeline and anchor block at different operating pressure and temperatures. Nonlinear finite element analyses that include modeling of soil-pipe and soil-block interactions are carried out to evaluate the design procedures. The results indicate that the concept used in current design procedures is fundamentally flawed because it is based on controlling forces rather displacements. Furthermore, both the thrust force and the resistance capacity are grossly miscalculated. The thrust force is significantly overestimated because it is based on a fully restrained anchor. The resistance capacity of the block that is calculated based on full mobilization of the passive resistance of soil is also drastically miscalculated because only a fraction of the passive resistance is mobilized. [ABSTRACT FROM AUTHOR]

Summary: This paper presents a simple and efficient analytical model for nonlinear response analysis of steel plate shear wall (SPSW) structural systems. The proposed model combines individual contributions of the boundary frame and the infill plate. It includes a nonlinear spring element that simulates the global response of the infill plate. The load‐deformation characteristic of this element is defined by a backbone curve and the pinched oriented Ibarra–Krawinkler hysteretic model. SPSW panels in the proposed model are differentiated as intermediate and end panels with two different backbone curves. Based on the theory of pure diagonal tension and experimental data, a basic backbone curve is first developed for the intermediate panel. For the end panel where the strength and stiffness of the infill plate are adversely affected by the flexibility of the anchor beam (the horizontal boundary element at the free end), the basic backbone curve is modified using appropriate strength and stiffness reduction factors. These factors are found by incorporating the strain energy of the anchor beam in the strain energy formulation of the theory of pure diagonal tension. Experimental results on several large‐scale SPSW specimens indicate that the proposed model reliably predicts the hysteretic behavior of SPSW structural systems. [ABSTRACT FROM AUTHOR]

A strong earthquake with moment magnitude of 7.3 occurred near the city of Sarpol-e Zahab in western Iran on November 12, 2017. The earthquake epicenter was located 10 km from Ezgeleh and 37 km from Sarpol-e Zahab. In this paper, damages to bridges located within 100 km from the epicenter are evaluated based on the field survey conducted one month after the earthquake. Bridges in the seismically affected cities and on primary roads leading to the city of Sarpol-e Zahab were inspected during the field survey. None of the inspected bridges were severely damaged, and they were all in service immediately after the earthquake. The observed damages were mostly minor in form of minor cracking across the decks, detachment of soil and abutments, and cracking of abutments. Some bridges were moderately damaged due to settlement and rotation of abutments which resulted in significant cracking of the deck. Damages occurred mainly in the abutments and to a lesser degree in the decks. Bridge bents in multi-span bridges did not experience any visible damage. This study indicates that concrete superstructures were more vulnerable than superstructures with steel girder. It also indicates that bridges with masonry abutments were more vulnerable than those with concrete abutments. Compared to single span bridges, the state of damage in multi-span bridges were more severe. [ABSTRACT FROM AUTHOR]