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Hongzhe Sun - One of the best experts on this subject based on the ideXlab platform.
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study on the Lap Splice behavior of post yield deformed steel bars in ultra high performance concrete
Construction and Building Materials, 2020Co-Authors: Mingke Deng, Hongkan Fan, Yong Yang, Hongzhe SunAbstract:Abstract Ultra high performance concrete (UHPC) is a type of cement-based composite material with ultra-high strength, high toughness and excellent durability. Furthermore, it has ultra-high bond strength of steel bar in UHPC. Influences of Splice length, fibre volume fraction, stirrup ratio and steel bar yielding on the Splice strength were studied by 21 groups direct tensile Lap-Splice tests. Two failure modes, splitting pull-out failure and steel bar rupture failure, appeared in the test. The Splice strength depends on the splitting strength of UHPC. The steel bar rupture failure occurred under rather small embedment length. Based on the elastic model of partly cracked thick-walled cylinder, in the post-yield phase, the localized Splice strength in elastic and plastic domains were calculated considering and ignoring the friction between the bar and UHPC, respectively. The stirrups are equivalent to the thickness of UHPC cover according to ACI 318–19. The mean Splice strength was calculated by averaging the bond strengths of elastic and plastic domains and agrees well with the test results. The results calculated with the formulas of GB50010-2010, ACI 318–19 and ACI 408R-03 may be conservative to estimate the minimum yield Splice length (MYSL) and minimum ultimate Splice length (MUSL). The proposed theoretical method in this paper can calculate the MYSL and MUSL accurately. The MUSL is about 1.8 times of MYSL.
Mingke Deng - One of the best experts on this subject based on the ideXlab platform.
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study on the Lap Splice behavior of post yield deformed steel bars in ultra high performance concrete
Construction and Building Materials, 2020Co-Authors: Mingke Deng, Hongkan Fan, Yong Yang, Hongzhe SunAbstract:Abstract Ultra high performance concrete (UHPC) is a type of cement-based composite material with ultra-high strength, high toughness and excellent durability. Furthermore, it has ultra-high bond strength of steel bar in UHPC. Influences of Splice length, fibre volume fraction, stirrup ratio and steel bar yielding on the Splice strength were studied by 21 groups direct tensile Lap-Splice tests. Two failure modes, splitting pull-out failure and steel bar rupture failure, appeared in the test. The Splice strength depends on the splitting strength of UHPC. The steel bar rupture failure occurred under rather small embedment length. Based on the elastic model of partly cracked thick-walled cylinder, in the post-yield phase, the localized Splice strength in elastic and plastic domains were calculated considering and ignoring the friction between the bar and UHPC, respectively. The stirrups are equivalent to the thickness of UHPC cover according to ACI 318–19. The mean Splice strength was calculated by averaging the bond strengths of elastic and plastic domains and agrees well with the test results. The results calculated with the formulas of GB50010-2010, ACI 318–19 and ACI 408R-03 may be conservative to estimate the minimum yield Splice length (MYSL) and minimum ultimate Splice length (MUSL). The proposed theoretical method in this paper can calculate the MYSL and MUSL accurately. The MUSL is about 1.8 times of MYSL.
Jean-philippe Charron - One of the best experts on this subject based on the ideXlab platform.
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3D Nonlinear Finite-Element Modeling of Lap Splices in UHPFRC
Journal of Structural Engineering, 2016Co-Authors: Fabien Lagier, Bruno Massicotte, Jean-philippe CharronAbstract:AbstractDevelopment in ultra-high-performance fiber-reinforced concrete (UHPFRC) structural applications that has taken place over the last two decades has generated innovative concepts that could significantly impact the concrete construction practice. The transition from conventional concrete with brittle behavior to strain-hardening behavior in direct tension allows consideration of the design of innovative structural components and offers development of new techniques for rehabilitation. Building on experimental results of internally instrumented reinforcing bars, this paper investigates the impact of tensile characteristics of UHPFRC on the performance of Lap Splice connections using a refined three-dimensional (3D) finite-element (FE) model at rib scale and a 3D concrete constitutive model implemented in a computer program. The results show that the model reproduces with accuracy the experimental behavior of Lap Splice connections in UHPFRC in terms of maximum strength, splitting failure mode, crack...
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Experimental investigation of bond stress distribution and bond strength in unconfined UHPFRC Lap Splices under direct tension
Cement and Concrete Composites, 2016Co-Authors: Fabien Lagier, Bruno Massicotte, Jean-philippe CharronAbstract:Abstract Several studies on tension Lap Splices have shown the improvement of bond strength using Ultra-high performance Fibre Reinforced Concrete (UHPFRC). The bridging effect of fibres on cracks improves the bond splitting strength substantially in comparison to normal concrete. This paper investigates the influence of fibre content on the strength of tension Lap Splice of reinforcing bars in UHPFRC without additional transverse reinforcement. Different Splice lengths and UHPFRC mixes were tested. Internal strain measurements were used to capture the force transfer mechanism and the evolution of longitudinal strain distribution and associated bond stresses. The bond performance is clearly related to the pre- and post-cracking tensile capacity of UHPFRC. At a distance exceeding 2 db from bar extremities, bond stress distribution at failure displayed a quasi-constant value regardless of the Lap Splice length up 10 db. This reveals for short Lap Splices that the bearing action of all ribs along the Splice length contributes equally in resisting the applied force. This experimental program provides experimental results for understanding the local force transfer mechanism in UHPFRC Lap Splice and contribute for further developments on bond in UHPFRC.
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Bond strength of tension Lap Splice specimens in UHPFRC
Construction and Building Materials, 2015Co-Authors: Fabien Lagier, Bruno Massicotte, Jean-philippe CharronAbstract:Abstract Outstanding tensile properties of ultra-high performance fibre reinforced concrete (UHPFRC) initiate innovative applications that take advantage of the bond improvement with reinforcement (precast element connections, seismic strengthening of deficient Lap Splices, etc.). Tests on Lap Splice specimens under direct tension were performed to investigate the influence of UHPFRC fibre content on bond strength. Three fibre contents (V f ) were examined with large reinforcing bar diameter (d b ) and multiple Splice lengths. According to strain hardening response of UHPFRC under direct tension, results show a considerable improvement of bond performance and splitting crack control. For UHPFRC mix with V f = 4% per volume, a Splice length of 12 d b was found sufficient to achieve yielding of 400 MPa reinforcement; with 10 d b length a bond stress around 10 MPa is reached. The contribution of the fibres was clearly highlighted through this experimental study, a strong relationship between the bond performance and both the maximum tensile strength and strain ductility of UHPFRC was noted.
Ari Wibowo - One of the best experts on this subject based on the ideXlab platform.
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CYCLIC BEHAVIOUR OF LIGHTLY REINFORCED CONCRETE COLUMNS WITH NON-DUCTILE Lap SpliceS
Jurnal Media Teknik Sipil, 2018Co-Authors: Rizki Amalia Tri Cahyani, Ari Wibowo, Wisnumurti WisnumurtiAbstract:Experimental testing of lightly reinforced concrete column was conducted to investigate the colLapse behavior of such column under cyclic lateral loading. Six column specimens, which have low longitudinal reinforcement and lack of confinement, were detailed with no Lap Splice, and non-ductile Lap Splice within or outside critical region. Placing the short, unconfined column's Lap Splice within critical region caused peak moment to fall short under its nominal moment capacity. In contrast, moment capacity of the specimen containing non-ductile Lap Splice outside critical region was in close agreement with those of specimen without Lap Splice. However, its inelastic damage region was moving away from the beam-column interface, resulted in degradation of drift capacity and rapid degradation of lateral strength. The presence of non-ductile Lap Splice outside critical region also potentially shift column's colLapse mechanism from flexure to flexure-shear critical. The ability of lightly reinforced concrete columns to maintain its axial load carrying capacity to large drift ratios despite heavy damage and significant loss of lateral load carrying capacity indicates that Lap Splice failure does not create sudden colLapse hazard.
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pengaruh rasio tulangan longitudinal dan letak Lap Splice terhadap daktilitas kolom bertulangan ringan akibat beban siklik
Jurnal Mahasiswa Jurusan Teknik Sipil Universitas Brawijaya, 2016Co-Authors: Desi Putri Kurniasari, Ari Wibowo, Siti NurlinaAbstract:Kolom merupakan struktur yang sangat vital dalam bangunan, jika terjadi kegagalan pada kolom maka kemungkinan gagalnya seluruh bangunan sangat lah tinggi. Bangunan tua dan rumah penduduk banyak yang dibangun dengan rasio tulangan longitudinal kurang dari 1% atau umumnya dikenal sebagai kolom bertulangan ringan, karena kurangnya pengetahuan pelaksana tentang struktur. Disisi lain, kerap muncul bangunan bertingkat yang mengharuskan penggunaan Lap Splice pada kolom untuk dapat meneruskan tulangan, dimana peletakan Lap Splice yang tidak tepat dapat mempengaruhi kegagalan suatu kolom. Penelitian ini dilakukan untuk mengetahui perilaku kolom bertulangan ringan dengan Lap Splice akibat gempa, perilaku yang dimaksud adalah daktilitas perpindahan. Pada penelitian ini digunakan dua jenis variasi yaitu rasio tulangan longitudinal (0.8% dan 1.1%) dan letak Lap Splice (bawah dan tengah). Terdapat 4 spesimen yang mewakili variasi tersebut dengan ukuran 150x160 mm dan f’c 25 MPa. Pengujian dilakukan dengan memberikan beban aksial konstan sebesar 0.1 Pu dan beban siklik hingga kolom melewati keruntuhan beban lateral dengan metode displacement control . Data yang dicatat untuk analisis daktilitas berupa data beban dan perpindahan tiap siklusnya. Hasil eksperimental dari penelitian ini menunjukkan bahwa kolom dengan rasio tulangan longitudinal 0.8% memiliki daktilitas yang jauh lebih besar dari kolom dengan rasio 1.1%, sedangkan kolom dengan letak Lap Splice di tengah memiliki daktilitas lebih besar dari kolom dengan letak Lap Splice di bawah, meskipun perbedaannya tidak signifikan. Kata kunci : perilaku kolom, beton bertulangan ringan, daktilitas perpindahan, beban gempa, keruntuhan kolom
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pengaruh letak Lap Splice dan rasio tulangan longitudinal terhadap pola retak kolom bertulangan ringan akibat beban siklik
Jurnal Mahasiswa Jurusan Teknik Sipil Universitas Brawijaya, 2016Co-Authors: Chaniva Adnin, Ari Wibowo, Sugeng P BudioAbstract:Kolom berperan penting dalam menahan beban gempa. Kegagalan pada kolom sama dengan keruntuhan total bangunan. Meskipun Indonesia memiliki intensitas gempa tinggi, banyak bangunan tua dan rumah penduduk yang menggunakan kolom dengan rasio tulangan dibawah 1% atau dikenal kolom bertulangan ringan. Dengan banyaknya bangunan bertingkat dibutuhkan adanya Lap Splice pada penulangan kolom. Berdasarkan penelitian yang telah ada sebelumnya, letak Lap Splice dapat mempengaruhi perilaku dari kolom. Penelitian ini ditujukan untuk mengetahui pengaruh rasio tulangan longitudinal dan letak Lap Splice terhadap pola retak kolom bertulangan ringan akibat beban siklik. Pada penelitian ini digunakan empat benda uji kolom dengan dimensi 150 mm x 160 mm x 800 mm. Terdapat 2 variasi dalam penelitian ini, yaitu rasio tulangan longitudinal (0,8% dan 1,1%) dan letak Lap Splice (dasar kolom SB dan ½ tinggi kolom SM). Benda dengan mutu beton 25 Mpa dan dilakukan pengujian pada umur lebih dari 28 hari. Pengujian ini dilakukan dengan memberikan beban aksial konstan sebesar 0,1 P, serta beban lateral siklik pada ketinggian 640 mm dengan metode displacement control. Diperoleh data beban dan perpindahan, serta pola retak tiap siklusnya. Hasil dari pembahasan data secara analisis aktual maupun teoritis menunjukkan benda uji dengan ρ v lebih tinggi (1,1%) tentunya memiliki momen kapasitas yang lebih besar daripada benda uji dengan ρ v lebih rendah (0,8%). Berdasarkan letak Lap Splice , retak pertama pada benda uji SM terjadi dengan perpindahan lebih kecil dibandingkan benda uji SB. Sehingga benda uji SM lebih kaku dibandingkan benda uji SB. Selain itu, dengan letak Lap Splice pada dasar kolom (SB), retak utama terjadi pada dasar kolom dengan pola retak dominan lentur. Dan untuk letak Lap Splice pada ½ tinggi kolom (SM), retak utama bergeser pada ketinggian sekitar 7,5 cm dengan pola retak dominan geser. Kata kunci: Beban gempa, metode displacement control, retak geser, retak lentur.
Katrin Beyer - One of the best experts on this subject based on the ideXlab platform.
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Extended Tension Chord Model for Boundary Elements of RC Walls Accounting for Anchorage Slip and Lap Splices Presence
International Journal of Concrete Structures and Materials, 2020Co-Authors: Danilo Tarquini, João Pacheco Almeida, Katrin BeyerAbstract:This paper presents a mechanical model for the simulation of reinforced concrete (RC) wall boundary elements with Lap Splices, which builds on the tension chord model. The model is composed of an assembly of components, each one accounting for a different source of deformation. Namely: (i) an anchorage-slip element accounting for the strain penetration of the longitudinal reinforcement into the foundation; (ii) a basic tension chord element evaluating the response outside the Lap Splice zone; and (iii) a Lap Splice element describing the behaviour within the Lap Splice region. For an imposed global displacement, the model provides the steel and concrete stress and strain distributions, the crack distribution and opening, as well as the global resisting axial force. For Spliced members, the ultimate displacement is computed through a semi-empirical relationship providing the average Lap Splice strain at failure. Validation is carried out against a series of uniaxial cyclic tests on RC wall boundary elements featuring both continuous and Spliced reinforcement; different Lap Splice lengths and confining reinforcement are considered. Overall, a good match is obtained between numerical and experimental results in terms of crack width, rebar strain distribution along the Splices and ultimate displacement.
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Experimental investigation on the deformation capacity of Lap Splices under cyclic loading
Bulletin of Earthquake Engineering, 2019Co-Authors: Danilo Tarquini, João Pacheco Almeida, Katrin BeyerAbstract:Correct detailing and positioning of Lap Splices is essential in order to prevent premature failure of reinforced concrete structural members. Especially before the introduction of capacity design guidelines, Lap Splices were often placed in member regions that undergo inelastic deformations under earthquake loading. When assessing the seismic performance of such members, not only the Lap Splice strength, which was assessed in previous studies, but also information on the deformation capacity of Lap Splices is required. This paper analyses the results of a recently concluded experimental programme on Spliced RC wall boundary elements tested under uniaxial tension–compression cyclic loading. The study aimed at investigating the influence of Lap Splice length, confining reinforcement and loading history on the deformation capacity of Lap Splices. The latter is defined as the average strain, at the onset of Splice failure, ascribed to deformations originating from the Lap Splice zone. Analysis of the test results showed that the deformation capacity of Lap Splices: (1) increases with Lap Splice length; (2) increases with confining reinforcement but the effectiveness of the confining reinforcement is dependent on the Lap Splice length; (3) decreases with larger imposed compression levels; (4) is larger for bottom-casted with respect to top-casted Lap Splices. Finally, an empirical model is proposed to estimate the strain capacity of Lap Splices, which provides a good fit with the experimental results.
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Influence of Lap Splices on the Deformation Capacity of RC Walls. II: Shell Element Simulation and Equivalent Uniaxial Model
Journal of Structural Engineering, 2017Co-Authors: Danilo Tarquini, João Saraiva Esteves Pacheco De Almeida, Katrin BeyerAbstract:Spliced longitudinal reinforcement may result in a reduction of both strength and displacement capacity of reinforced concrete (RC) members. This applies in particular when Lap Splices are located in regions where inelastic deformations concentrate, such as the plastic zone at the base of RC walls. This paper introduces a simple numerical model suitable for engineering practice to simulate the force-displacement response of RC walls with Lap Splices. Based on experimental data from 16 test units, an equivalent uniaxial steel stress-strain law is proposed that represents the monotonic envelope of the cyclic response of Spliced rebars in RC walls up to the onset of strength degradation. It allows for modeling Lap Splice response with finite element (FE) models while avoiding the use of complex interface bond-slip elements. A new semi-empirical expression for the strain at the onset of strength degradation is derived, which expresses the strain capacity of the Lap Splice as a function of the confining reinforcement ratio and the ratio of Lap Splice length to shear span of the wall. The proposed equivalent constitutive law was included in shell element models to predict the force-displacement response of the test unit set of RC walls. Results demonstrated the ability of this approach to adequately capture the peak strength and displacement capacity of the Spliced units.
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Influence of Lap Splices on the Deformation Capacity of RC Walls. I: Database Assembly, Recent Experimental Data, and Findings for Model Development
Journal of Structural Engineering, 2017Co-Authors: João Saraiva Esteves Pacheco De Almeida, Danilo Tarquini, Ovidiu Prodan, Katrin BeyerAbstract:Recent postearthquake missions have shown that reinforced concrete (RC) wall buildings can experience critical damage owing to Lap Splices, which led to a recent surge in experimental tests of walls with such constructional details. Most of the 16 wall tests described in the literature thus far were carried out in the last six years. This paper presents a database with these wall tests, including the description of a new test on a wall with Lap Splices and a corresponding reference wall with continuous reinforcement. They complement the existing tests by investigating a Spliced member with a shear span ratio smaller than two, which is the smallest among them. The objective of this database is to collect information not just on the force capacity but mainly on the deformation capacity of Lap Splices in reinforced concrete walls. It is shown that (1) well-confined Lap Splices relocate the plastic hinge above the Lap Splice, (2) Lap Splices with adequate lengths but insufficiently confined attain the peak force but their deformation capacity is significantly reduced, and (3) short and not well-confined Lap Splices fail before reaching the strength capacity. The analysis of the test results, which are used in the companion paper for the finite element analysis of walls with Lap Splices, indicates in particular that the confining reinforcement ratio and the ratio of shear span to Lap Splice length influence the Lap Splice strain capacity.
