Hybrid Cable-stayed Bridge Research Articles

Experimental Study of the Steel-Concrete Connection in Hybrid Cable-Stayed Bridges

A new steel-concrete connection with Perfo-Bond Strip (PBL) connectors for a hybrid cable-stayed bridge was adopted and introduced. Push-out tests of the PBL connectors were performed to evaluate the shear capacity of perfobond ribs in steel-concrete connections. Test results revealed that the shear strength of a perfobond rib in a twin configuration is about 80% of that of a single independent perfobond rib. To investigate the safety and reliability of the proposed connection from a practical perspective, a model test with a scale of 1:2 for the joint of the hybrid girder was carried out on site. During the test, stress distribution, crack resistance ability, and relative slip between concrete and steel were measured carefully to investigate the mechanical performance, force transmission, strength, and stiffness of the steel-concrete connection. The test results revealed that concentrated stress at the loading section in steel girders can be reduced and transferred uniformly through the joint to the concrete sections by a combined axial and shear force transmission mode with the help of bearing plate and multiple parallel perfobond ribs. The findings from the tests and analyses are considered to be of special significance to the design and construction of steel-concrete connections in hybrid cable-stayed bridges.

Development of Optimal Structural System for Hybrid Cable-Stayed Bridges Using Ultra High Performance Concrete

This study developed an optimal structural system for the hybrid cable-stayed bridge expected to have a durable lifetime of 200 years and of which major structural members are made of ultra high performance concrete (UHPC) with 200 MPa-class compressive strength. This innovative cable-stayed bridge system makes it possible to reduce each of the construction and maintenance costs by 20% compared to the conventional concrete cable-stayed bridge by improving significantly the weight and durability of the bridge. Therefore, detail design is carried out considering a real 800 m cable-stayed bridge and the optimal structure of the hybrid cable-stayed bridge is proposed and verified.

Conceptual Design of Hybrid Cable-Stayed Bridge with Central Span of 1000 m Using UHPC

Ultra-high performance concrete (UHPC) is featured by a compressive strength 5 times higher than that of ordinary concrete and by a high durability owing to the control of the chloride penetration speed by its dense structure. The high strength characteristics of UHPC offer numerous advantages like the reduction of the quantities of cables and foundations by the design of a lightweight superstructure in the case of the long-span bridge preserving its structural performance through axial forces and structures governed by compression. This study conducted the conceptual design of a hybrid cable-stayed bridge with central span of 1000 m and exploiting 200 MPa-class UHPC. The economic efficiency of the conceptual design results of the hybrid cable-stayed bridge with central span of 1000 m and of Sutong Bridge, the longest cable-stayed bridge in the world, was analyzed.

New strategy of substructure method to model long-span hybrid cable-stayed bridges under vehicle-induced vibration

Hybrid cable-stayed bridges consist of steel and concrete bridge segments, of which steel–concrete joints are of great importance and raise strong research interest. Due to the limitation of the traditional methods, i.e., the member finite element (FE) method and Mixed Dimensional Coupling (MDC) method, the present study proposes a substructure method to model long span bridges. The current application of the substructure method is to extract some specific parts of the whole structure to refine and analyze them. Different from the routine substructure approach, here the entire structure is modeled in detail and divided into many substructures. All the substructures are then condensed into super-elements except the concerned part. The application of the method is then illustrated through numerical studies of the vehicle–bridge coupling vibration of the Jingyue Yangtze River Bridge with a main span of 816 m. The entire bridge is first divided into many substructures with a reasonable length. Among them, the concerned substructure with 23.8 m in length including the steel–concrete joint is modeled in detail but not formed into super-element, while all the other components are modeled in detail and formed into super-elements using the component mode synthesis (CMS) method. All the components including both the super-elements and non-super-elements are then assembled into a complete and fine full bridge model. Finally, the model is used for the vehicle-induced dynamic analysis under deterministic traffic flows. The results show that the joint works well, and the transition between the steel girders and concrete beams is very smooth.

Investigation on mechanics performance of cable-stayed-suspension hybrid bridges

The cable-stayed-suspension hybrid bridge is a cooperative system of the cable-stayed bridge and suspension bridge, and takes some advantages and also makes up some deficiencies of both the two bridge systems, and therefore becomes strong in spanning. By taking the cable-stayed-suspension hybrid bridge, suspension bridge and cable-stayed bridge with main span of 1400 m as examples, the mechanics performance including the static and dynamic characteristics, the aerostatic and aerodynamic stability etc is investigated by 3D nonlinear analysis. The results show that as compared to the suspension bridge and cable-stayed bridge, the cable-stayed-suspension hybrid bridge has greater structural stiffness, less internal forces and better wind stability, and is favorable to be used in super long-span bridges.

Structural Health Monitoring of a Long-span Cable-stayed Bridge

Proper selection of methods and instruments for structural health monitoring (SHM) of bridges will assure reliability, durability, and lower life cycle costs. This article provides a case study for in-service monitoring of a recently built long-span hybrid cable-stayed bridge, Queshi Bridge, in southern China. Three parameters, namely the cable forces, main structure deformations, and their vibrations are monitored with different methods at regular intervals over a time period of about four years. The results to date are very encouraging as the SHM systems installed in the bridge have been able to provide vital information about the state of health of the bridge to the transportation authorities.

Prediction of vortex-induced oscillations of a bridge girder with span-wise varying geometry

There are cases where it is difficult to predict the amplitude of vortex-induced oscillation accurately by using a single wind tunnel 2D model. An example of them is proposed sine-curved hybrid cable-stayed bridge girder with span-wise varying geometry discussed in this study. First, the aerodynamic damping force was measured for five 2D models in a wind tunnel. Next, a linearized method for 3D numerical analysis was prepared and then applied to predict the amplitude of the oscillation for this bridge. Since one of the triangular fairings examined was found to be effective in suppressing the oscillation, it was decided that the bridge girder with this fairing should be included in its detailed design. Also, the precision of the solution obtained by the numerical analysis was found to be sufficiently high for the case where much smaller number of 2D models was used.

Investigation Of Earthquake Resistance And Cost Effect On Hybrid Cable-stayed Bridge With Two Girders

Nowadays hybrid structures composed of concrete and steel are widely constructed in Japan and known to be superior against earthquakes and to be cost effective. In this study, a bridge of 340m in length which crosses a valley was used as a model object, in which the hybrid cable-stayed bridge of two grders was proposed as the most economical bridge, having significant resistance against earthquake. After having carried out investigations from many different aspects, this paper focuses on the subjects as shown below. By imposing bearing support condition on the top of pier (for example. fixed bearing, movable bearing. base isolation bearing) as parameters, dynamic analyses were carried out by using 3-dimensional analytical models that introduce inelastic elements in a RC pier. As a result, the optimum dimension of the R C pier and bearing conditions were determined. T o investigate the effects o n the isolation bearing. parametric analysis on characteristics of the isolation bearing was carried out. In addition to a design for a hybrid cable-stayed bridge with two girders. a PC continuous rigid frame bridge and steel arch bridge were designed to investigate cost effectiveness. By calculating quantities of works, cost comparisons of these bridges was carried out. I t was concluded from these investigations that by using the isolation bearing the proposed bridge was superior in cost effectiveness and earthquake resistance.