Academic literature on the topic 'Lap splice'

Behavior of lap splices formed by CFRP rolls has been studied. CFRP rolls have been prepared by using CFRP sheets of a certain width. Strengthening methods that use CFRP rolls as reinforcement may require an epoxy anchored lap splice due to the conditions at the strengthening regions. It may not always be possible to strengthen the region by using only one roll fan anchored at both ends, but using two rolls from opposite faces of the member and lap splicing them at the middle so that they act as a single roll. Lap splice behavior can be studied best by using flexural beam bond specimens if the reinforcing material is steel. Therefore, it has initially been suggested that flexural beam specimens reinforced for flexure with CFRP rolls as tension reinforcement can be used in studying the lap splice behavior. However, due to the difficulties encountered in the beam tests, another type of test specimen was introduced, which was a direct pull-out specimen. In this type of test specimen, lap spliced CFRP rolls have been tested under direct tension, in which the tension has been applied by making use of concrete end blocks that transfer the tension to the rolls. Eleven tests have been made in total. Full material capacity of the rolls could not be achieved due to premature failures. However, important conclusions and recommendations have been made for future studies.

Minimum requirements for lap splices in reinforced concrete members, stated in building codes of TS-500 and ACI-318, have a certain factor of safety. These standards have been prepared according to research results conducted previously and they are being updated according to results of recent studies. However the reliability of lap splices for minimum requirements needs to be investigated. For this purpose, 6 beam specimens were prepared according to minimum provisions of these standards. The test results were investigated by analytical procedures and also a parametric study was done to compare two standards. For smaller diameter bars both standards give safe results. Results showed that the minimum clear cover given in TS500 is insufficient for lap spliced bars greater than or equal to 26 mm diameter.

Non-contact lap splices placed within a single concrete placement are often used and have been studied in previous research projects. However, non-contact lap splices used with each bar in a different concrete placement such that there is a cold joint between the bars, have not been investigated. This situation is found in the repair of adjacent box beam bridges and in the construction of inverted T-beam systems, among others. It is vital to understand whether the same mechanisms are present across a cold joint with two different types of concrete as are present in traditional non-contact lap splices. In this research, eight T-beam specimens with non-contact lap splices were tested. The spacing between the bars, the splice bar blockout length, and presence of transverse bars were varied to study the effectiveness of the splices. The beams were tested in four point bending so that the splice region was under constant moment and the tension forces in the spliced bars were constant. End and midspan deflections were measured along with surface strain measurements at midspan and at the quarter span points, top and bottom. Gap openings were also measured at the ends of the blockouts. The main conclusions found from this research are that beams containing non-contact lap splices were able to develop nominal capacity with the bar spacing less than or equal to 4 in. and the blockout between 17 and 20 in. long. Extending the blockouts and adding transverse bars underneath the splices did not add to the capacity.<br>Master of Science

This thesis investigates the tensile performance of unconfined lap splices in specimens constructed from interlocking compressed earth block (ICEB) units. All lap splice specimens were constructed from hollow ICEB half units with one side grouting channel. ICEB units used in this research were exclusively produced from the Soeng Thai Model BP6 block press. The BP6 block press is currently manufactured in Thailand under the guidance and direction of the Center of Vocational Building Technologies (CVBT). All ICEB units and grout constructed for this research were created from mix proportions of soil, sand, cement, and water. Rebar bar sizes were restricted to M10 (#3) and M13 (#4) for all lap splice specimens due to the limited area of the hollow 2-inch diameter rebar cavity of the ICEB unit. The limited size and strength of the ICEB units also made the use of larger bar diameters impractical. Three ICEB unit types of varying strengths (3.78 MPa, 7.81 MPa, and 11.38 MPa) and three grout types of varying strengths (1.35 MPa, 7.47 MPa, and 15.50 MPa) were developed and used to construct all specimens. The measured ICEB lap splice specimen strengths were compared against the predicted strength calculated from the Masonry Standards Joint Committee (MSJC). Findings suggested that the MSJC design equation did not adequately predict the lap splice strength of specimens, particularly for specimens constructed from weaker materials. The measured ICEB lap splice results were used to create a new ICEB lap splice design equation. This paper also investigates the compressive performance of fully grouted ICEB prisms constructed from the range of ICEB unit and grout strengths stated above. Findings suggested that the compressive strength of fully grouted ICEB prisms were exclusively controlled by the compressive strength of the ICEB units used to construct the prism. The strength of the grout had no discernable effect on the strength of the fully grouted prism. A design equation was proposed to calculate prism strengths based on measured strength results of ICEB units.

Self-compacting concrete is an innovative construction material<br>its priority to normal vibrated concrete is that there is not any vibration requirement. Bond strength of reinforcement is one of the key factors that ensures the usefulness of any reinforced concrete structure. In this study, 6 full-scale concrete beams spliced at the mid-span were tested under two-point symmetrical loading. Test variables were bottom cover, side cover, free spacing between longitudinal reinforcement, lap-splice length and presence of transverse reinforcements within the lap-splice region. Specimen SC_22_44_88_800 had cover dimensions close to the code limits and had 36db lap splice length. This specimen showed flexural failure. Specimen SC_44_44_44_710 had 32db lap splice and cover dimensions greater than code minimums. This specimen showed yielding primarily. With the increasing loading, however, bond failure occurred with side splitting. ACI 408 descriptive equation for normal vibrated concrete predicted bar stresses of the unconfined specimens produced with self-compacting concrete acceptably well. The predicted values were lower than the measured values to be on the safe side. The error varied between 3.4% and 6.5%. All predictions of the ACI408 descriptive equation was higher than the measured bar stresses of the confined specimens produced with SCC. All the calculated values were unsafe. The error varied between 10.6% and 34.5%. Specimen SC_44_22_22_530_T4 with 24db lap splice length had side cover and spacing between bars 63.3% and 56.7% less than the ACI 318 limits. The calculated bar stress was 21.6% higher than the measured value. The main reason of the deviation was inadequate cover dimensions. In specimen SC_44_22_22_530_T6, number transverse reinforcement was increased to 6 stirrups to overcome the small cover and spacing problem. However, increased number of stirrups inside a small side and face cover caused weak plane and measured bar stress decreased.

assessed and strengthened. Performance evaluation of deficient buildings has become a major concern due to devastating earthquakes in the past. In order to justify new provisions in design and assessment codes, experiments and analyses are inherently necessary. In this thesis study, investigations into the behaviour of two deficient reinforced concrete frames built at Middle East Technical University&rsquo<br>s Structural and Earthquake Laboratory and tested via pseudo-dynamic tests were made. These frames were modelled on the OpenSees platform by following methods of analyses outlined in the Turkish Earthquake Code of 2007 (TEC 2007) and ASCE/SEI-41-06. Both deficient frames were essentially the same, with the only difference being the presence of insufficient lap splices, which was the focus of the study. Time history performance assessments were conducted in accordance to TEC 2007&rsquo<br>s damage state limits and ASCE/SEI 41-06&rsquo<br>s performance limits. The damages observed matched the performance levels estimated through the procedure outlined in TEC 2007 rather well. Specific to the specimen with lap splice deficiencies, ASCE/SEI 41-06 was overly conservative in its assessments. TEC 2007&rsquo<br>s requirements for lap splice lengths were found to be conservative in the laboratory and are able to tolerate deficiencies up to 25% of the required length. With respect to mathematical models, accounting for materials in deficient systems by using nominal but reduced strength properties is not very efficient and unless joint deformations are explicitly accounted for, local deformations cannot be captured.

A prototype reinforced concrete moment frame representative of low-rise office buildings in the Central and Eastern United States from the 1950s-1970s was designed and selected for evaluation under seismic loads. A plane frame specimen from the prototype was incorporated into the design of a test-bed of four full-scale, side-by-side nominally identical structures that could be evaluated independently. The testing of the first frame serves as the topic of this dissertation. The specimen was two bays x two stories x 9-ft. wide. A new method for testing full-scale structures under seismic loads was proposed that used a hydraulic linear inertial shaker (LIS) to impart seismic loads. The response of the structure was monitored using 155 strain gages, 38 linear variable differential transformers, six string potentiometers, and 42 accelerometers. The response of the frame to a series of 25 load histories using the nees@UCLA LIS was marked by gradual structural softening and minimal yielding of the steel reinforcing throughout the structure. At a first interstory drift of 1.5% some yielding of the reinforcing bars was measured. Between 1.5% and 2% first interstory drift, a global sway mechanism formed when the failure of a splice at the base of the first story west column led to a cascading set of failures within other first-story column splices. The experimental behavior suggests previous scaled testing of similar structures may have inadequately represented the vulnerability column splices. The design of the test-bed, response of the structure to seismic loads, qualitative evaluation of the test method, and implications on future research are discussed.

Made available in DSpace on 2016-12-23T14:05:54Z (GMT). No. of bitstreams: 1 Danielli Cristina Borelli Cintra.pdf: 4222911 bytes, checksum: 0db55771987e1317b678d8aff9ba3ab7 (MD5) Previous issue date: 2013-11-28<br>The lap splice of the longitudinal reinforcement of columns positioned at the base, widely used in the execution of multiple floors structures in reinforced concrete floors, is the most vulnerable point in the pathological manifestations columns of buildings, compromising the structural performance and durability of the building. This region suffers from the stage of concrete, the high concentration of bars and high altitude release of concrete that promote segregation of the aggregate, and hinder access to the consolidation. During the life of the structure, is a region of high concentration of efforts, especially in columns bracing and often exposed to aggressive agents, such as the accumulation of waste chemicals, cleaning and humidity. The present work is an experimental and statistical study of the behavior at break of 31 short columns reinforced concrete subjected to concentric compression. All columns possessed cross section of 19cm x 19cm, height 170cm, concrete strength around 30MPa and longitudinal geometric rate of 0.88%. Varied only the position and the length of the lap splice to analyze the influence of these two factors and the interaction between them in the capacity of the columns. Are analyzed qualitatively manufacturing procedures samples of columns, which were close to the conditions of execution of the columns in the works. We used a factorial design to statistically analyze the experimental results, which confirmed the hypothesis that none of the factors applied, even the interaction between them, would be significant for the load capacity of the columns<br>A emenda por traspasse de armadura longitudinal posicionada na base de pilares, largamente utilizada na execução de estruturas de múltiplos pavimentos em concreto armado, consiste num dos pontos mais vulneráveis às manifestações patológicas em pilares de edifícios, comprometendo o desempenho estrutural e durabilidade da edificação. Tal região é prejudicada, desde a etapa de concretagem, pela alta concentração de armadura e pela altura elevada de lançamento do concreto, que promovem a segregação do agregado, além de dificultarem o acesso para o adensamento. Durante a vida útil da estrutura, é uma região de alta concentração de esforços e geralmente exposta a agentes agressivos, como o acúmulo de resíduos de produtos químicos, de limpeza e umidade. O presente trabalho trata-se de um estudo experimental e estatístico do comportamento até a ruptura de 31 pilares curtos de concreto armado, submetidos à compressão centrada. Todos os pilares possuíam seção transversal de 19cm x 19cm, altura de 170cm, resistência do concreto em torno de 30MPa e taxa geométrica de armadura longitudinal de 0,88%. Variou-se apenas a posição da emenda e o comprimento de traspasse da armadura longitudinal para analisar a influência desses dois fatores e da interação entre eles na capacidade de carga dos pilares. São analisados qualitativamente os procedimentos de fabricação das amostras de pilares, que foram próximos às condições de execução de pilares em obras. Utilizou-se um planejamento fatorial para analisar estatisticamente os resultados experimentais, que confirmou as hipóteses de que nenhum dos fatores adotados, nem mesmo a interação entre eles, seriam significativos para a capacidade de carga dos pilares

The results of an investigation into the performance of reinforced concrete beam-column subassemblages containing lap spliced reinforcement in the potential plastic hinge region of a beam are presented. Two specimens were tested with simulated seismic loading. One specimen complied with the New Zealand Concrete Design Code, NZS 3101:1982, except for the placement of the lap splices. The second specimen contained beam reinforcement details from a building constructed in the early 1960s. Current concrete design codes specify lap splices should not be placed in beam potential plastic hinge regions where inelastic reversing stresses are possible during seismic events. During testing the transverse steel specified for the confinement of the lap splices was unable to prevent bond deterioration between the spliced bars once inelastic bar strains had developed at one end of the splice. The failure of the lap splices led to a loss of lateral load capacity and a low level of ductility from the specimen. Reinforced concrete buildings designed to pre-1970s codes may be considered inadequate when viewed in light of the provisions in current codes for seismic design. The testing of beam details taken from one such building indicates insufficient anchorage existed for the plain longitudinal beam bars in the joint. The loss of bond for the plain bars began in the initial load cycles of the test and led to a lack of specimen stiffness and lateral load capacity. The presence of the lap splices is considered to have accelerated the loss of bond from the bars. Testing investigating the performance available from plain bar reinforced subassemblages should use anchorage for the bars that represent the conditions in the existing structure. The rapid loss of bond from the bars during cyclic loading can lead to the member end connections influencing the test results.