Lap Splice Research Articles

Equivalent analytical modeling of adequate reinforcement noncontact lap splices under monotonic loads

AbstractLap splices constructional details are widely used for connecting prefabricated parts. They are usually located in regions where larger inelastic deformation capacity can be expected, such as the base of RC walls and beam‐column joints. An equivalent analytical model of adequate reinforcement noncontact lap splices is first proposed in this study. The noncontact lap spliced reinforcement is simplified as continuous reinforcement with variable diameter combined with the equivalent stress–strain law. The method allows for monotonic yield and degradation of tension and compression noncontact lap splices. Parametric analysis is further performed to investigate the influence of lap splices details on the bearing capacity and deformation capacity. Finally, five shear wall finite element models are established to verify the equivalent modeling method. The proposed method can more accurately reflect the deformation capacity and bearing capacity of the noncontact lap splices region.

Behavior and Splice Length of Deformed Bars Lapping in Spirally Confined Grout-Filled Corrugated Duct

This paper discusses the behavior of grouted noncontact lap splices under monotonic tension load. Deformed bars lapped through a grout-filled corrugated duct, and a spiral reinforcement was preembedded in the connection to improve tensile strength of the splice. The experimental results show that bond failure splices are always failed by the pullout of the preembedded bar other than the grouted bar. As the spiral pitch distance is not greater than 75 mm, the tensile strength generally improves with the increment of volumetric spiral reinforcement ratio due to the higher confinement provided by the spiral bar. Compared with the spiral bar diameter, the spiral pitch distance provides more dominant effect on the tensile strength of the connection. Based on the experimental results and the development length specified in ACI 318-14, a revised equation with a reduction factor of 0.76 was proposed to predict the required minimum lap length of spirally confined lap splice.

Exploratory study on the utilization of recycled wood as raw material for cross laminated timber

Cross-Laminated Timber (CLT) has been gaining interest in recent years as an attractive and environmental-friendly building material. As such, CLT has been used for structural components in building constructions such as apartments, commercial buildings, or offices. CLT predominantly uses newly harvested lumber as a raw material. In this study, however, CLT fabricated using recycled wood was explored for possible utilization in wood structures. The recycled wood was obtained from wooden boxes, wooden pallets, and scrap wood from lumber suppliers, and their mechanical properties were tested. The average tension-parallel-to-grain strength of these recycled woods was 52.2 MPa, while their average compression-perpendicular-to-grain and compression-parallel-to-grain strength were 20.6 and 4.0 MPa, respectively. Four CLT beams of 2 m-length, 100 mm-width, and 130 mm-depth glued with epoxy adhesive were tested to measure their flexural strengths. A set of two CLT beams was loaded on upright and lying positions, and their average flexural strengths were 8.1 and 7.6 MPa, respectively. The effects of lamina lap splices and adhesives on CLT beam flexural strength were studied. Apparently, adding several variations of lap-splices and adhesives has marginal impact on CLT beam flexural strength.

Cyclic tests on beam-column joints of SCOPE system with different key slot lengths and corrosion levels

A frame Structure Comprised of Precast Prestressed Concrete Components (SCOPE) has been widely used in China. According to previous research, the length of non-contact lapped splice between U-shape bars and the steel strands plays an important role in seismic performance of the beam column joint. However, the splice may deteriorate due to corrosion when the frame is used in coastal region. This paper presents an experimental investigation on seismic behaviors of the corroded beam-column joints of the SCOPE system. Ten specimens with different key slot lengths and different corrosion levels were tested under cyclic loading, and their hysteretic loops, envelop curves, bearing capacity, and energy dissipation were compared and analyzed. It is observed that the corrosion of steel bars would significantly affect seismic behaviors of the structure, and most specimens showed flexural failure, while for the seriously corroded specimens with long key slots, failure might occur at the interface between the precast beam and the key slot due to severe corrosion and bond failure of the lapped splice. In general, the energy dissipation of specimens with shorter slot length was greater than that of specimens with the longer key slot under the same corrosion level. However, as the corrosion level increases, the difference became smaller.

Effect of Using Recycled Coarse Aggregate to the Bond Stress in Term of Beam Splice Specimens

In fact, demolition west disposal represents a serious problem in the civil engineering work since such materials are accumulated in large quantities. In this way, using these materials in new construction is considered a good sustainable and cost effective solution. The basic objective of this study is to investigate the behavior of lap splice when recycled coarse aggregate is used in structural members by experimental program. This program comprises casting 12 beam splice specimens. Two mix designs are proposed with nominal compressive strength of 20 and 30 MPa, more precisely, the degrees of coarse recycled aggregate partial replacement ratio that taken throughout this study are 0, 50 and 100% respectively using a crushed concrete casted with the same original mixes defined. Since a considerable lack of information was observed about the role of recycled coarse aggregate when the bond stress is taken into account, the beam splice specimens during this study were devoted to investigate lap splice bond strength in both singly and doubly beams to discover the desired behavior in tension and compression. The results showed that the degree of recycled coarse aggregate decreases the consequent bond stress in term of beam splice specimens for singly and doubly beams. The brittle failure behavior is evident in the entire beam specimens that conducted throughout this study.

Experimental seismic behavior of squat shear walls with precast concrete hollow moulds

This study proposes an innovative precast shear wall system, called an EVE precast hollow shear wall structure (EVE-PHSW). Precast panels in EVE-PHSW are simultaneously precast with vertical and horizontal holes. Noncontact lap splices of rebars are used in vertical joints connecting adjacent precast panels for automated prefabrication and easy in situ erection. The seismic behavior of EVE walls was examined through a series of tests on six wall specimens with aspect ratios of 1.0∼1.3. Test results showed that EVE wall specimens with inside cast-in situ concrete achieved the desired “strong bending and weak shear” and failed in shear mode. Common main diagonal cracks and brittle shear failure in squat cast-in situ walls were prevented. Inside cast-in situ concrete could significantly improve the shear strength and stiffness of EVE walls. The details of boundary elements (cast-in situ or prefabricated) and vertical joints (contiguous or spaced) had little effect on the global behavior of EVE walls. Noncontact lap splices in vertical joints could enable EVE walls to exhibit stable load-carrying capacity through extensive deformations. Evaluation on design codes revealed that both JGJ 3-2010 and ACI 318-14 provide conservative estimation of shear strength of EVE walls, and EVE walls achieved shear strength reserves comparative to cast-in situ walls. The recommended effective stiffness for cast-in situ walls in ASCE 41–17 appeared to be appropriate for EVE walls.

Influence of Coating on Mechanical Performance of Lap-Spliced Carbon Fiber-Textile Reinforced Mortar (TRM)

In this study, the effect of coating methods in the lap splice area on mechanical performance of lap-spliced carbon textile reinforced mortar (TRM) composites was investigated. The coating methods included textile reinforcement coated with epoxy, textile reinforcement coated with aluminum oxide powder and epoxy, and textile reinforcement coated with aluminum oxide powder, epoxy, and carbon fiber fabrics. It appears that the coated specimens showed higher peak strength and ultimate strain than those of the uncoated one.

The effect of joints model to the vibration characteristics of wood

The One piece of the wooden beam has different vibration characteristics compared to the two pieces of wood with a joint. One of the parameters measured is the dynamic stiffness of wood. The method used is a technique in which the vibration excitation test using a hammer with a rubber head. The wood used in this study is Gofasa (vitex cofassus). The Properties of wood was using the data from previous studies. Vibration characteristic of a piece of wood was used for comparison purposes. Two pieces of wood have joined and secured by bolts. Cantilever beam model has used with the knock in a perpendicular direction to the wood fibres. The joints model used to excitation test is the plain scarf, hooked scarf, half lap splice, and tabled splice. All of these models were tested to determine the characteristics of vibration. The results showed the different vibration characteristics for each model. The results are used as a recommendation of the best models in distributing the vibration from the vibration source.

Seismic behaviour of RC columns with welded rebars or mechanical splices of reinforcement

The extension of existing RC buildings is a challenging process, which requires efficient connection between existing and new materials to guarantee load transferring between the lap-spliced longitudinal columns\' reinforcement. Therefore, the length of the columns\' starter bars is a crucial factor, which decisively affects the seismic response of the new columns. In particular, when the length of the starter bars is short, then the length of the lap splices of reinforcement is inadequate to ensure load transfer between steel bars and concrete, with an indisputable detrimental impact on the seismic behaviour of the columns. Moreover, in most of the existing RC buildings the column starter bars are of particularly short length, while they have probably been bent, cut or corroded. In the present study, the effectiveness of both welded rebar and mechanical splices of reinforcement in ensuring load transferring between the starter bars and the longitudinal reinforcement of the new column was experimentally evaluated. Four cantilever column subassemblages were constructed and subjected to earthquaketype loading. Three of the specimens were used to examine different types of shielded metal arc welding (SMAW), while in the fourth subassemblage mechanical splices were tested. The hysteretic response of the columns was evaluated and compared to the behaviour of a fifth specimen with continuous reinforcement, tested by Kalogeropoulos and Tsonos (2019). Test results clearly demonstrated that the examined types of SMAW were equally satisfactory in ensuring the ductile seismic performance of the columns, while the mechanical splices found to be more susceptible to exhibit slipping of the bars.

Prediction of bond performance of tension lap splices using artificial neural networks

Recently, machine learning has been widely used in civil engineering, because better design can be achieved using the advanced computer intelligence and test results. In the present study, to improve design reliability and to extend design application range for the development and lap splice lengths, an artificial neural network model (ANN) was presented using 1008 existing experimental studies for splice tests. Although some of the test parameters are out of the limitations of design codes, all test results were used for the ANN to extend design application range considering present-day construction materials and practices. From a parametric study with the ANN, the effect of design variables was investigated, and predictions by the ANN were compared with existing design equations. Finally, based on the parametric study result, modifications were proposed for existing design equations to consider the effect of non-uniform bond stress distribution and the effect of cover concrete and transverse bars, as well as to extend design application range. Comparisons showed that the modifications improved the accuracy of the design methods. The high accuracy to the large number of existing test results confirms that the modifications based on the ANN can improve design reliability and also can extend design application range for the development and lap splice lengths.

Variation of Splice Length with Bending Behavior of Reinforced Concrete Beams

The splice length of the distribution depends on the concrete stress with reinforcement, generally the bond stress is tested by pull out testing where pull out testing can provide a good comparison between the efficiency of the attachment of various types of reinforcement surfaces. However, the bending behavior of the beam is very different from the pure tensile pull out test. This study presents the effects of variations of lap splice (30db, and 40db) in the area of beam pull. The first test object was a beam BN - 0 (non splice length) which was a normal beam. The second test object was a beam BN - 30db with the splices length(ld) of 480 mm and the third test object was a 40db beam with the splice length (ld) of 640 mm. The test used a pure bending test method with loading of Two Point Loads on a simple support beam. The results gained from this study obtained flexural capacity in BN-0 (non lap splices) of 115.15 kN, flexural capacity of BN - 30db of 90.484 kN, and beam flexural capacity of BN-40db of 124.848 kN. The displacement ductility at BN-30db decreased 35% to BN-0 and displacement ductility at BN-40db increased 48% to BN-0, the bond strength attached to BN-40db increased 2.92% to BN-30db. The splice length (ld) 40db was able to develop the ability to achieve yield stress loads and the spread of crack concentration around the joints.

Experimental investigation on the deformation capacity of lap splices under cyclic loading

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.

Bond-slip modelling of reinforced concrete lap splices subjected to low and high strain rates

This paper presents an analytical model developed to predict the flexural load-deformation behavior of reinforced concrete members containing tension lap splices. The proposed model incorporates the effect of reinforcement slip of the lap splice and the effect of high strain rates on bond characteristics and material properties of concrete and steel. The main advantages of the proposed model are that bond-slip phenomena are captured through the use of pseudo-material stress-strain relationships, rather than giving consideration to the continuum of reinforcement and slippage over the entire structural element. Material properties and associated dynamic increase factors (DIF) are defined using accepted formulations. A suitable bond-slip law is presented and modified to account for the influence of strain rates on bond characteristics. Beam failure criteria are expressed in terms of a flexural failure of the member or a bond splitting failure of the splice. A comparison of the analytical predictions with experimental data demonstrated that the proposed analysis technique can reasonably predict the flexural response of beams with tension lap splices. The results also show that the model is equally applicable for use at low- and high- strain rate loading, such as those generated during blast and impact loading.

Effectiveness of Various Techniques Using FRP for the Strengthening of R. C. Beams with Tension Lap Splices

This paper presents an experimental program conducted to investigate the flexural performance of RC beams with tension reinforcement lap splice strengthened using externally bonded FRP different techniques in splice region. The specimens were reinforced on the tension side with four deformed bars spliced at mid span. The tested beams are of 3200 mm total length and 250*120 mm cross section, tested in positive bending. The considered parameters were splice length, type of FRP (glass or carbon), strengthening techniques in splice region (externally confine strips around cross section, Near Surface Mounted technique "NSM" stirrups, externally bonded sheets or bars on the tension face, number of GFRP strips layers (one layer, two layers, and three layers), and shape of NSM stirrups (Box or U shape). No additional anchorage mechanism or bonding methodology was applied for the FRP strips on the concrete except the epoxy adhesive. The effect of these factors on the failure of modes, the ultimate load, the bond strength and that the ductility were investigated. The results indicated that all applied strengthening techniques were efficient in improving the bond strength of the lap splices, the ductility, and the load-deflection behavior of the tested beams, especially when strips were installed over the splice region. This study approved that NSM technique gave more prominent simplicity of employ.

Polymer Concrete for Bridge Deck Closure Joints in Accelerated Bridge Construction

Prefabricated concrete bridge deck panels are utilized in Accelerated Bridge Construction (ABC) to simplify bridge deck construction. Concrete with good bond and shear strength as well as excellent flowability is required to fill bridge deck closure joints. This paper discusses the use of polymer concrete (PC) for bridge deck closure joints in ABC. PC produced using poly methyl methacrylate and standard aggregate was tested. Test results of PC are compared to Ultra-High Performance Concrete (UHPC). Development length, lap splice length and shear strength of unreinforced PC were tested. It is shown that PC has a development length of 3.6 to 4.1 times the reinforcing bar diameter that is close to one-half the development length of 6 to 8 times the bar diameter required with UHPC. PC also showed a shorter splice length compared with that reported for UHPC. Finally, unreinforced PC showed shear strength that is twice that of UHPC. It is evident that using PC in bridge deck closure joints in ABC can improve constructability and provide cost-savings and eliminate reinforcing bar congestion.

Tensile Behaviors of Lap-Spliced Carbon Fiber-Textile Reinforced Mortar Composites Exposed to High Temperature

The tensile behaviors of textile-reinforced mortar (TRM) composites made with carbon fiber textile and alumina cement-based mortar were investigated through direct tensile tests. Three different surface treatment details in the lap splice area were used to improve the tensile behaviors of the TRM composites: carbon fiber textile impregnated by epoxy, carbon fiber textile coated with aluminum oxide powder following epoxy impregnation, and carbon fiber textile coated with aluminum oxide powder following both carbon fiber fabric attachment and epoxy impregnation. Three different lap splice lengths were used 180, 200, and 220 mm. In addition, the tensile properties of TRM composites following exposure to high temperature were investigated as well. In this test, TRM test specimens were exposed to two different temperature histories with maximum values of 250 and 350 °C. The results of the test specimens according to the test parameters were analyzed in terms of initial stiffness, cracking strength, corresponding strain at cracking, modulus of elasticity in the cracked stage, peak strength, and ultimate strain. The influence of lap splice length on the tensile behaviors of the TRM composites was analyzed and discussed. The surface treatment in the overlapping region showed ductile behavior and resulted in a significant improvement of the peak strength and ultimate strain over the untreated lap splice textile. Following exposure to high temperature, the TRM composites showed a reduction of tensile responses compared to those cured at room temperature. In addition, a prediction model developed in the previous study was used to predict the tensile behaviors of the lap-spliced carbon fiber-textile reinforced mortar composites exposed to high temperature, and the prediction by the model showed a good agreement with the experimental results.

Effect of polypropylene fibers on bond performance of reinforcing bars in high strength concrete

Abstract Adequate bonding between reinforcement and concrete plays a vital role in the proper performance of reinforced concrete as a composite material. Hence it is important to evaluate the influence of various factors on the bond behavior of reinforcement and concrete. In this study, a total of 8 beam specimens with tension lap splice at the midspan and 12 concentric pullout specimens are fabricated to investigate the effect of polypropylene fibers on bond performance of reinforcement in high strength concrete (HSC). Fibers are added to concrete mixture by 0.15%, 0.30% and 0.45% volume fraction of concrete. The detrimental effect of polypropylene fiber on the workability of mixture restricts the use of a high amount of polypropylene fiber in mixtures. Splice specimens made of fiber reinforced concrete presented a greater number of cracks, higher failure loads and deflections and also larger crack width at their failure stage. Failure deflections of splice specimens made of fiber reinforced concrete are 20% higher than that of plain concrete specimens on average. After splitting failure, load carrying capacity of all beam specimens dropped to almost zero and the addition of polypropylene fibers did not provide residual capacity for the specimens. The slope of the bond stress-slip curves of specimens experiences a sudden change at the cracking load. Results indicate that existing prediction equations for bond strength are acceptable and even yield more accurate values when polypropylene fibers are added to concrete mixtures. The results of beam and pullout tests demonstrated that pullout test is not suitable to evaluate the effect of polypropylene fibers on bond strength.

Uniaxial Cyclic Tests on Reinforced Concrete Members with Lap Splices

This data paper presents the quasi-static uniaxial cyclic tests of 24 reinforced concrete members, of which 22 feature lap splices and 2 are reference units with continuous reinforcement. The objective of the experimental program is to investigate the influence of lap splice length ( ls), confining reinforcement, and loading history on the behavior of lap splices. Particular attention is placed on the measurement of local deformation quantities, such as lap splice strains and rebar-concrete slip. Details of the geometry and reinforcement layout of the specimens as well as the employed test setup, instrumentation, and loading protocols are provided. The global behavior of the test units, including the observed crack pattern and failure modes, are discussed. The organization of the experimental data, which are made available for public use under DOI: 10.5281/zenodo.1205887, is outlined in detail.

Experimental study on seismic performance of precast LSECC/RC composite joints with U-shaped LSECC beam shells

Precast beam-column joints are key components of precast reinforced concrete (RC) frame structures. The complex reinforcement details in the joint zone due to high seismic demand have made the prefabrication and construction process in regions with high earthquake intensity difficult to perform. As a type of high-performance fiber-reinforced cementitious composites (HPFRCCs), low-shrinkage engineered cementitious composite (LSECC) exhibits stable strain hardening and multiple cracking properties with a dry shrinkage even lower than that of normal concrete. A partial substitution of concrete with LSECC can significantly improve the seismic performance and damage tolerance of beam-column joints and help simplify the reinforcement details in the joint zone. This paper proposes a novel precast LSECC/RC composite beam-column joint using U-shaped precast LSECC beam shells. Five interior beam-column sub-assemblages were tested under cyclic loading, including one monolithic and four precast specimens. Parameters including lap splice length, transverse and longitudinal reinforcement ratios were studied. The proposed construction process was proven to be both easy and fast. The performance of the precast joints were evaluated in terms of the ultimate capacity, deformation, energy dissipation, shear distortion and strength of the joint core. The test results showed that the proposed joints could effectively simplify the joint reinforcement details while maintaining the required seismic performance. The diagonal cracks in the joint zone without transverse reinforcement were well controlled. A few stirrups in the joint zone could reduce the shear deformation and improve the energy dissipation capacity. The shear strength of the LSECC joints without any transverse reinforcement were found to be similar to the nominal shear strength of well-confined normal concrete joints suggested by ACI 318-14.

Research on pseudo-static cyclic tests of precast concrete shear walls with vertical rebar lapping in grout-filled constrained hole

In this paper, the seismic behaviors of four precast shear wall specimens and one cast-in-place shear wall specimen are investigated by pseudo-static test method. For the precast shear wall specimens, a new type of assembled rebar lap splices with prepared grout-filled holes and constraining spiral hoops were applied. Different vertical rebar lap splice positions and different rebar lap lengths at the horizontal assembly joints of the precast specimens were designed and fabricated in order to compare their seismic behaviors with the cast-in-place specimen. The geometric size and rebars of four precast specimens are totally same as those of the cast-in-place specimen. By analysis of test results including the load-lateral drift hysteresis curves, crack propagation and rebar strains, the failure modes, bearing capacity, hysteretic characteristics, ductility, rigidity degeneration and energy dissipation of all specimens were obtained and compared. The test results show that the precast concrete shear walls with horizontal assembly joints by this kind of rebar connection have good seismic behaviors and could be equivalent to the cast-in-place shear walls on the conditions of specified construction details.