Papers by Keyword: Bond Properties

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Authors: Shu Tong Yang
Abstract: Ground anchors have been very practical in a wide range of geotechnical structures. Good bond properties at the anchor-mortar and mortar-rock interfaces can ensure transmitting an applied tensile load to a load bearing structure efficiently. The bond performance between the mortar and rock is necessary to be studied. A push-out test of mortar from rock block can be used to analyze the interfacial properties between the two materials. In this paper, an analytical model is proposed to determine the push-out capacity of mortar from rock block. Based on the deformation compatibility at the interface, the compressive stress in the mortar and the interfacial shear stress at the mortar-rock interface are formulated at different loading stages. By modeling interfacial debonding as an interfacial shear crack, the push-out load is then expressed as a function of the interfacial crack length. In virtue of the Lagrange Multiplier Method, the maximum push-out load is determined. The validity of the proposed model is verified with the experimental results. It can be concluded that if the interfacial parameters at the mortar-rock interface are obtained, the push-out capacity of mortar from rock block can be accurately determined using the proposed model. The proposed solution in this paper would provide a good theoretical basis in evaluating the stability of ground anchors in practice.
2396
Authors: Giovanni Muciaccia, Andrea Consiglio, Gianpaolo Rosati
Abstract: Typical applications for post-installed rebar connections consist in overlapping joints with existing reinforcement or anchoring of the reinforcement at a slab or beam support. At cold state it may be shown by testing that a post-installed rebar system can develop the same bond resistance with the same safety margin as cast-in-place rebar. Consequently, anchorage length and lap length for post-installed rebars can be calculated as for cast-in-place according to the Eurocode 2 provisions. However, when subjected to temperature, the decay in bond properties for post-installed systems is significantly more dramatic than for cast-in-place rebars. The paper presents the result of an experimental campaign carried out on a post-installed connection using a vinylester polymer, investigating the effects on the bond strength both of the temperature and of different testing conditions. Finally, design criteria are provided and applied to a typical case study consisting in a post-installed solid slab.
783
Authors: Giovanni Muciaccia, Gianpaolo Rosati
Abstract: The original development and use of Self-Compacting Concrete (SCC) in Japan started from the problem of the durability of concrete. Indeed, the reduction in the number of skilled workers, and the consequent poor compaction of structures, was a topic of great concern in the eighties, and helped the introduction of SCC. More recently, SCC is being commonly used in solid concrete slab in residential buildings for its excellent flowability. Additionally, to reduce structural self-weight without excessively affecting the slab thickness (which could represent a major issue in this applications), lightweight concrete represents a preferable solution. In this type of structure the development of anchorage or lap length becomes crucial, thus requiring a proper understanding of the bond mechanism. The result of an experimental campaign to assess bond properties for Lightweight Self-Compacting Concrete (LWSCC) are presented in this paper. The main investigated parameter is the bar size (ranging from 8 to 24mm) while the cover to diameter ratio and the bonded length to diameter ratio were kept constant. The experimental results are finally compared with code predictions.
211
Authors: Zhi Yong Liu, Lei Yu, Da Ji Li, Kun Rong Wang
Abstract: In this paper the anticorrosion properties of steel bars coated with polymer modified cement-based coatings in chloride solution were evaluated. Then the pullout tests were conducted using coated and uncoated steel bars embedded in concrete specimens and the bond properties between concrete and bars were tested. The results show the steel bars coated with epoxy emulsion modified cement-based coating (HY) and elastic copolymer emulsion modified cement-based coating (GT) have satisfactory anticorrosion properties in 3.5% NaCl solution for 96h. But the pullout tests display that the bond strength between the concrete and the steel bars coated with GT coating is much lower than that of the bars coated with HY coating and the uncoated specimens. The bond stress between the concrete and the bars coated with pure acrylate emulsion modified cement-based (CB) coating is the highest among the three coatings, but the resistance to chloride permeability of CB coating is poor. The results indicate the special epoxy-cement-based coating (HY) is more suitable for applying to the anticorrosion coating for steel bars in chloride condition.
1066
Authors: Wei Jun Yang, Li Shan Li, Yan Wang
Abstract: After the pilot study about different-aged ceramsite concrete specimens, the curve and the formula about the ceramsite concrete splitting strength with age developing are obtained, the curve and the formula about the relative bond strength with age are analyzed, it provides a theoretical basis for the project production of ceramsite concrete practice.
3744
Authors: Shun Bo Zhao, Xin Xin Ding, Shi Ming Liu
Abstract: Based on the experimental studies, finite element models were built using ANSYS software to simulate the bond properties of steel bars in machine-made-sand concrete (MSC), which considered the nonlinear bond behavior of interface between steel bar and MSC. The concrete strength and the bond length of steel bar are considered as the main parameters for calculation. The complete bond-slip curves of plain and deformed steel bars are well simulated comparing those obtained from the experimental studies. The study gives an theoretical method to analyze the bond properties of steel bar in MSC.
176
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