Search

The article “An analytical inverse analysis to determine equi-biaxial tensile properties of strain-hardening UHPFRC from ringon-ring test”, written by Xiujiang Shen, Eugen Bruhwiler, Emmanuel Denarie and Wanghu Peng was originally published electronically on the publisher’s.

The equi-biaxial tensile properties of strain-hardening UHPFRC are determined and investigated based on an original analytical inverse analysis of results from ring-on-ring tests. First, the analytical inverse analysis method is developed based on the elastic slab bending and yield line theories. Using this method, a new objective criterion for the determination of the elastic limit stress of strain-hardening UHPFRC is provided, and a point-by-point inverse analysis is used to obtain the strain value at the end of hardening. This method reduces uncertainties regarding assumptions and avoids any iterative procedures. The inverse analysis results are put into perspective with experimental evidence, particularly based on DIC measurements. Moreover, the uniaxial tensile properties are also derived from the inverse analysis of 4PBT results and compared with the equi-biaxial tensile properties from the proposed inverse analysis. The inverse analysis results show a 18% lower elastic limit stress, and almost equivalent tensile strength of UHPFRC subjected to equi-biaxial stresses, compared with the corresponding values from uniaxial stress. Moreover, a relatively small equi-biaxial strain at the end of hardening is highlighted.

This paper presents issues in the design concept, analysis, and test results of a harp-shaped single span cable-stayed bridge, Hongshan Bridge, located in Changsha, Hunan Province, China. The bridge has a 206 m span, with a pylon inclined at 58° from the horizontal and 13 pairs of parallel cable stays without a back stay. This paper discusses the design approach for the main components of the bridge. Emphasis will be put on the following three aspects. First, the weight of the pylon and all dead loads of the main girder in addition to part of the live loads must be in a balanced condition. Second, the main girder should be an orthotropic steel-concrete composite box girder because of the superior safety and weight reduction of this type of structure. Third, the cable stays should be anchored at the neutral axis of the pylon to prevent the development of high secondary moments caused by other anchor approaches. Furthermore, based on results from tests carried out on three models, namely, scaled full model ...

This article describes a newly developed design of semi-integral bridge abutment which can reduce the soil disturbance behind the abutment caused by thermal changes. The case study described is of the Liguanhe Bridge in China. The bridge has a pile-type embedded abutment. On the abutment cap, a reinforced concrete backwall against the backfill separates the end beam from the backfill. A 25-millimetre gap between the end beam and the backwall keeps them separate even when the bridge expands in summer. The approach slab anchored to the end beam overpasses the backwall and shifts the deck thermal movements to the structure/road interface. Sliding elastomeric bearings rest on the end beam and there are multi-layer plastic films laid beneath the approach slab, and asphalt felts between the approach slab and backwall. The longitudinal restraint of the superstructure is derived from the friction between the approach slab and backwall and between the retaining block and the approach sub-base.

Publisher Summary The chapter explores the design of the main girder of a harp-shaped cable-stayed bridge. It discusses the issues related to the design of the main girder of a 206 meters span harp-shaped cable-stayed bridge in Changsha, China. The details of the main girder are presented in the chapter. Then the conceptual design of the bridge is explained in depth. Based on technical and economic comparison between the steel, concrete and composite girder, the latter most is most preferable for the design. Due to the special features of the harp-shaped cable-stayed bridge, a special composite spine girder is selected and adopted. Further, structural analyses for the main girder, such as its global characteristics, the fatigue and the local stability of the steel girder, and the working characteristics of the concrete deck are presented in the chapter.

Publisher Summary The chapter presents the issues of design and experiment results of a harp-shaped single span cable-stayed bridge, Hongshan Bridge, located in Changsha, China. The inclined pylon is a prestressed concrete structure, and the main girder is an orthotropic steel-concrete composite box girder. The chapter presents a scaled full model test to verify the design and analyze the results of the bridge. The chapter investigates the experimental study of the local stability of the steel box girder and the dynamic characteristics of the model with different auxiliary equipments. The chapter provides recommendations that the pylon should be in a status of axial compression when the girder is loaded by all dead loads and half live loads, and the weight of the pylon and the girder deck should be in a balanced condition. For this type of bridge, the main girder prefer to an orthotropic steel-concrete composite box girder, and the concrete deck is installed near the neutral axis of the girder. To prevent the cracking of the concrete deck, the prebending prestressing method is presented in the chapter. The chapter also indicates that setting temporary piers in the construction of the bridge is a practical and economic approach to improve wind-resistance characteristics.

The biaxial flexural response of strain-hardening UHPFRC circular slab element is investigated experimentally and analytically using the ring-on-ring test. The Digital Image Correlation (DIC) technology is applied to capture the 3D full-field of strain and deflection of the tensile surface through the whole loading process. Based on DIC analysis, a quasi-elastic limit is determined additionally to characterize the flexural response of UHPFRC under biaxial stress condition. The random and uniform distribution of matrix discontinuities in UHPFRC in the quasi-elastic domain, as well as multiple fictitious crack formation in hardening domain, is highlighted. In addition, ring-on-ring test and Four-Point Bending Test (4PBT) results are compared with special emphasis on flexural strength and characteristics of matrix discontinuity development. The results show higher ultimate flexural strength and energy absorption capacity at ultimate limit from the ring-on-ring test, and almost same flexural strength at the quasi-elastic limit for both tests. Finally, a simplified inverse analysis is proposed for the ring-on-ring test based on the elastic slab bending and yield line theories. The calculation results indicate a 19% lower tensile elastic limit stress of the UHPFRC, while an almost equivalent value of tensile strength is obtained from the ringon-ring test, compared with the 4PBT results. (C) 2020 Elsevier Ltd. All rights reserved.

The equi-biaxial tensile properties of strain-hardening UHPFRC are determined and investigated based on an original analytical inverse analysis of results from ring-on-ring tests. First, the analytical inverse analysis method is developed based on the elastic slab bending and yield line theories. Using this method, a new objective criterion for the determination of the elastic limit stress of strain-hardening UHPFRC is provided, and a point-by-point inverse analysis is used to obtain the strain value at the end of hardening. This method reduces uncertainties regarding assumptions and avoids any iterative procedures. The inverse analysis results are put into perspective with experimental evidence, particularly based on DIC measurements. Moreover, the uniaxial tensile properties are also derived from the inverse analysis of 4PBT results and compared with the equi-biaxial tensile properties from the proposed inverse analysis. The inverse analysis results show a 18% lower elastic limit stress, and almost equivalent tensile strength of UHPFRC subjected to equi-biaxial stresses, compared with the corresponding values from uniaxial stress. Moreover, a relatively small equi-biaxial strain at the end of hardening is highlighted.