Special Issue on Design, Analysis, and Construction of Segmental Bridges

Abstract

Owing to a prevailing desire for expedited construction (accelerated bridge construction) with minimal traffic disruption, lower lifecycle costs, appealing aesthetics, and adaptability to curved roadway alignment, segmental bridges have become a primary choice for major transportation projects throughout the world, and methods of designing and constructing them have rapidly developed over the last two decades. Accordingly, research on the design, construction, analysis, and rehabilitation of segmental bridges has become one of the most interesting and timely subjects in bridge engineering. This special issue of the Journal of Bridge Engineering is intended to promote and improve the design, construction, and analysis of this type of bridge. There were nine technical papers, one case study, and one technical note selected for this special issue. These papers present up-to-date design, analysis, and construction methods of different types of segmental bridges, including girder, cable-stayed, extradosed, and composite segmental bridges. Conceptual design is one of the most complex and important issues in bridge design. In the paper entitled “Segmental Bridges in Chongqing, China,” Man-Chung Tang presents unique and innovative designs for three different types of concrete segmental bridges: the Shibanpo segmental girder bridge, the second Wujiang cable-stayed bridge, and the Jiayue extradosed bridge. Shibanpo Bridge is the world’s longest concrete segmental girder bridge with a main span of 330 m (1,082 ft). The second Wujiang Bridge is a nonsymmetrical cable-stayed bridge with two uneven single column towers and a single plane of cables. The Jiayue Bridge is a partially cable-supported segmental girder bridge with a main span of 250 m (820 ft) and a height of about 90 m (295 ft) over normal water level. The author’s design philosophy regarding how to select the most suitable bridge type in terms of function, economics, aesthetics, and environmental issues will be greatly beneficial to bridge engineers. The paper “Spatial Embedded Slip Model for Analyzing TimeRelative Coupling Effects of Creep and Prestress upon PC Bridges” by Wei-zhen Chen and Cheng Ma present a spatial embedded slip model that consists of a three-dimensional isoparametric element, a truss element, and a nonthickness bond element to simulate concrete, a tendon, and an interface, respectively. The bond element is embedded into the slip model via the virtual nodes introduced at the intersection points of the tendon and concrete. The proposed model allows tendons to embed the concrete in any pattern, without consideration of layout or direction of tendon and is very convenient in finite-element meshing. The model has been verified and can be applied to concrete segmental bridge time-related coupling effect analysis of creep, shrinkage, relaxation, etc. “Serviceability and Ultimate Safety Checks of Segmental Concrete Bridges through N-M and M-V Interaction Domains” by Michele Fabio Granata and Antonino Recupero presents a new method for performing capacity checks in segmental bridges by considering the axial force (N), bending moment (M), and M–shear force (V) interaction domains for cracking and construction stages, as well as serviceability and M–V interaction domains for ultimate limit states. The analytical results for a segmental bridge built by cantilevering indicate that safety checks performed on the basis of current approximate assumptions and specifications may lead to unsafe design and that the proposed methodology can provide a more reliable bridge structural design by allowing engineers to take into account simultaneously any aspect related to cross section strength in serviceability and ultimate limit states. In the paper, “Use of Construction Stages to Review a Bridge Finite-Element Model,” Nimse et al. present the field-measured results from different construction stages for the Veterans’ Glass City Skyway posttensioned concrete segmental cable-stayed bridge in Toledo, Ohio, USA. This bridge has a main span of 464.8 m (1,525 feet) with two box girders connected by Delta frames with complex mechanical behaviors. The baseline analytical model of the bridge is reviewed using the measured response to construction loads. The boundary conditions and geometry of the model are updated during the various stages of construction. The behavior of the model during construction was verified using construction loads. The tested and analytical results are instructive for bridge engineers and the identified theoretical models are useful for similar bridge structure analysis. In the paper “Behavior of Concrete Segmental Box Girder Bridges with Open Webs,” Liu et al. discuss the mechanical behavior of concrete segmental bridges with open webs. This type of bridge can significantly reduce self-weight and offers more pleasing aesthetics. The authors propose a space-frame lattice model for analyzing these special structures and investigate the distinguished mechanical characteristics of this special type of segmental bridge. The authors’ proposed design methods for reducing the principle stresses are useful for bridge engineers. The paper “Torsional Analysis of Multicell Concrete Box Girders Strengthened with CFRP Using a Modified Softened Truss Model” by Chai et al. presents a new analytical method for predicting the torsion capacity and behavior of reinforced concrete multicell box girders strengthened with carbon fiber reinforced polymer (CFRP) sheets. The conventional softened truss model is modified to consider the influence of CFRP on the torsion resistance as an external reinforcement to multicell box girders. In the proposed method, the concrete torsion problem is solved by combining the equilibrium conditions, compatibility conditions, and constitutive laws of materials, taking into account the confinement of the concrete with CFRP sheets. The proposed method has been verified by test results and can be used for the torsion analysis of concrete segmental bridges strengthened by CFRP. In the paper “Behavior of a Continuous Composite Box Girder with a Prefabricated Prestressed-Concrete Slab in Its HoggingMoment Region,” Su et al. propose to use a prefabricated prestressed concrete slab in the negative moment region for a continuous composite box girder to improve its serviceability.