Bilateral loading experiment on and analysis of concrete piers using mortar‐jointed ultra‐high‐strength fibre‐reinforced concrete precast formwork

Abstract

The seismic performance of a reinforced concrete pier structure depends greatly on the plastic hinge region at the base of the pier. To improve the plastic hinge region of the structure, we propose using ultra-high-strength fibre-reinforced concrete (UFC) IntroductionIn the event of bridge damage following a major earthquake in which the concrete of reinforced concrete piers supporting the superstructure is crushed, the capacity to retain flexural strength and axial force is diminished, thus reducing the serviceability of the piers. In order to establish a system for early post-quake relief and recovery, earthquake damage must be minimized even in the event of a major earthquake. There is also a considerable need for damage-free bridge pier structures that can be used in locations where post-quake inspection would be difficult, such as bridge piers in river channels and piers located on median strips. It is generally known [1,2] that if a reinforced concrete pier with a rectangular cross-section is subjected to seismic forces in two horizontal directions and in the vertical direction, the ductility of the pier is lower than in the case where only one direction is considered. In order to ensure the post-quake serviceability of reinforced concrete piers, it is important to prevent crushing failure of the concrete even under earthquake loading in two horizontal directions, where damage processes are complex.To address these needs, the authors propose a reinforced concrete pier structure made from ultra-highstrength fibre-reinforced concrete (UFC), a concrete-based material with high compressive and flexural strength, in the form of precast formwork constituting the base structure of the pier (hereinafter referred to as "UFC piers") [3,4]. The authors have also demonstrated that the proposed structure has high ductility with respect to external forces acting in two directions [5]. The basic idea behind this pier design is to increase the strength of the concrete cover in the plastic hinge zone by using UFC precast formwork. The concrete cover made of UFC can resist seismically induced flexural compressive stresses, enabling the seismic performance and ductility of the pier to be provided by the undamaged core concrete. Moreover, in order to resist flexural loading in two directions, the thickness of UFC precast formwork at corners can be increased to avoid damage in the corner regions.The UFC precast formwork has a number of horizontal joints in order to distribute earthquake-induced flexural cracks and thus minimize the concentration of damage, particularly at cross-sections. The initial idea was to form horizontal joints by laying wire netting in layers to separate steel fibres in UFC [5]. However, the number of induced cracks turned out to be smaller than expected and to be only about two or three in each zone after a cyclic loading test. The UFC piers may not have been able to achieve the anticipated performance because of premature rebar damage. For the horizontal joints capable of inducing a stable number o...

Relation between slab thickness and dimensions of formwork

“…Yamanobe et al described the structural characteristics of a pier with a base cast using mortar‐jointed UFC formwork. C …”

Axial compression ratio limit for self‐centering precast segmental hollow piers

“…More ED solutions were proposed for precast segmental piers, such as external mild steel ED device, friction ED caused by sliding of segment joints, external viscous damping device, and so on . Some advanced materials including ultra high performance concrete, elastomeric bearing pad, carbon fiber reinforced polymer, and engineered cementitious composite (ECC) were also used in experimental researches to improve the seismic performance of precast segmental piers and achieved expected function . Furthermore, some numerical methods were developed to predict the seismic resistance of precast segmental piers …”

“…[12][13][14][15][16] Some advanced materials including ultra high performance concrete, elastomeric bearing pad, carbon fiber reinforced polymer, and engineered cementitious composite (ECC) were also used in experimental researches to improve the seismic performance of precast segmental piers and achieved expected function. [17][18][19] Furthermore, some numerical methods were developed to predict the seismic resistance of precast segmental piers. 4,20 From those researches, unbonded PT are deemed to be effective and important for self-centering capacity for precast segmental piers, and ED devices can enhance ED capacity to limit maximum deformation.…”

Cyclic response of a precast composite hollow reinforced concrete column using longitudinal rebars and base plate

“…Since then, and particularly in the past 30 years, the number of precast bridges has increased substantially because of the advantages of precast construction compared to traditional cast‐in‐place techniques . Yamanobe et al studied the structual charateristics of a pier with a base cast using mortar‐jointed, ultra‐high‐strength, fibre‐reinforced concrete (RC) formwork . Lu suggested precast concrete structures in the future .…”