• Journal of the Korea institute for structural maintenance and inspection
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• 제17권4호
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• pp.48-56
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• 2013

Prestressed concrete (PSC) members are readly available in civil engineering applications due to the convenience of construction and easy of quality control in the manufacturing process of the member. Especially, half-depth precast concrete composite slab, which is one of the PSC flexural members is developed recently using the long-line method. The half-depth precast concrete composite slabs are composed of the precast concrete and the in-situ concrete placed at the site. In this paper, we present the results of experimental investigations pertaining to the pretensioning efficiency and the flexural behavior of half-depth precast concrete composite slab which is made of precast PSC manufactured by the long-line method. In the long-line method, the pretensioned precast member is manufactured simultaneously, by tensioning tendons at once. In addition, we suggest the equation that can estimate the flexural strength of half-depth precast concrete composite slab reasonably by considering the effects of rebar embedded in the precast PSC flexural member.

• Steel and Composite Structures
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• 제39권4호
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• pp.435-451
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• 2021

Shear lag effect was a significant mechanical behavior of steel-concrete composite beams, and the effective flange width was needed to consider this effect. However, the effective flange width is mostly determined by static load test. The cyclic vehicle loading cases, which is more practical, was not well considered. This paper focuses on the study of shear lag effect of the concrete slab in the negative moment region under fatigue cyclic load. Two specimens of two-span steel-concrete composite beams were tested under fatigue load and static load respectively to compare the differences in the negative moment region. The reinforcement strain in the negative moment region was measured and the stress was also analyzed under different loads. Based on the OpenSees framework, finite element analysis model of steel-concrete composite beam is established, which is used to simulate transverse reinforcement stress distribution as well as the variation trends under fatigue cycles. With the established model, effects of fatigue stress amplitude, flange width to span ratio, concrete slab thickness and shear connector stiffness on the shear lag effect of concrete slab in negative moment area are analyzed, and the effective flange width ratio of concrete slab under different working conditions is calculated. The simulated results of effective flange width are compared with calculated results of the commonly used specifications, and it is found that the methods in the specifications can better estimate the shear lag effect in concrete slab under static load, but the effective flange width in the negative moment zone under fatigue load has a large deviation.

• Journal of Korean Society of Steel Construction
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• 제27권1호
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• pp.63-75
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• 2015

In this study, Composite beam flexural capacity was investigated experimentally using angle as a shear connector. The main experimental parameters are the size and the spacing of the angle and the overall behavior of before and after composite. Also, the composite beam bending performance when it used with hollow PC slab and the general RC slab was compared. When determining that it synthetically, the flexural capacity of the composite beam with angle shear connector estimated 25% to 55% more strength than the nominal strength. Effects of strength parameters of composite beam by angles shear connector are size and spacing of the angle. As expected, the larger and the narrower spacing of the angles, the more strength the composite beam have. In addition, the performance of the composite beam with a hollow slab was well demonstrated by the test.

• Steel and Composite Structures
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• 제25권5호
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• pp.523-534
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• 2017

Cable-supported ribbed beam composite slab structure (CBS) is proposed in this study. As a new cable-supported structure, it has many merits such as long span availability and cost-saving. Inspired by the previous research on cable-supported structures, the fabrication and construction process are developed. Pre-stress design method based on static equilibrium analysis is presented. In the algorithm, the iteration convergence can be accelerated and the calculation result can be kept in an acceptable precision by setting a rational threshold value. The accuracy of this method is also verified by experimental study on a 1:5 scaled model. Further, important parameters affecting the mechanical features of the CBS are discussed. The results indicate that the increases of sag-span ratio, depth of the ribbed beam and cable diameter can improve the mechanical behavior of the CBS by some extent, but the influence of strut sections on mechanical behavior of the CBS is negligible.

• Steel and Composite Structures
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• 제18권2호
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• pp.375-394
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• 2015

This paper presents the results of four long-term experiments carried out to investigate the time-dependent behaviour of composite floor slabs with particular attention devoted to the development of non-uniform shrinkage through the slab thickness. This is produced by the presence of the steel deck which prevents moisture egress to occur from the underside of the slab. To observe the influence of different drying conditions on the development of shrinkage, the four 3.3 m long specimens consisted of two composite slabs cast on Stramit Condeck $HP^{(R)}$ steel deck and two reinforced concrete slabs, with the latter ones having both faces exposed for drying. During the long-term tests, the samples were maintained in a simply-supported configuration subjected to their own self-weight, creep and shrinkage for four months. Separate concrete samples were prepared and used to measure the development of shrinkage through the slab thickness over time for different drying conditions. A theoretical model was used to predict the time-dependent behaviour of the composite and reinforced concrete slabs. This approach was able to account for the occurrence of non-uniform shrinkage and comparisons between numerical results and experimental measurements showed good agreement. This work highlights the importance of considering the shrinkage gradient in predicting shrinkage deformations of composite slabs. Further comparisons with experimental results are required to properly validate the adequacy of the proposed approach for its use in routine design.

• Computers and Concrete
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• 제29권3호
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• pp.127-144
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• 2022

To investigate the flexural stiffness of the steel-composite beam, the contributions of the concrete slab and steel beam to the stiffness were considered separately. The method for flexural stiffness of the composite beam, considering the stiffness of the concrete slab and steel beam, was proposed in this paper. In addition, finite element models of the composite beams were established and validated. Parametric analyses were carried out to study the effects of different parameters on the neutral axis distance reduction factors of the concrete slab and steel beam. Afterward, the neutral axis distance reduction factors were fitted, and the stiffness combination coefficients of the two parts were solved. Based on the stiffness combination coefficients, the flexural stiffness of the composite beam can be obtained. The proposed method was validated by the tested and analyzed results. The method has a simple form and high accuracy in predicting the flexural stiffness of the steel-concrete composite beam, even though the degree of shear connection is less than 0.5.

• Journal of Korean Society of Steel Construction
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• 제13권1호
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• pp.29-40
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• 2001

Steel frames are increasingly used in commercial buildings. and most steel frames are designed to achieve composite action with the concrete floor slab. The advantages of 'composite construction' are now well understood in terms of structural economy. good performance in service. and ease of construction. But. these conventional composite construction system are difficult to apply steel framed apartment due to their large depth. So. in this study we developed Semi Slim Floor system which could reduce the overall depth of composite beam. Semi Slim Floor system is a method of steel frame multi-story building construction in which the structural depth of each floor is minimised by incorporating the steel floor beams within the depth of the concrete floor slab. Twelve composite slab specimens with different deck-type. slab width. with or without stud bault and concrete topping thickness were tested to evaluate the flexural capacity.

• Journal of the Korea institute for structural maintenance and inspection
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• 제22권5호
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• pp.64-71
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• 2018

This paper provides the results for experimental study on longitudinal shear performance for new-concept composite slabs embedded with silence insulator. Longitudinal shear capacity tests are used to predict characteristics of composite action between the concrete block, silence insulator and deckplate. A total set of 7 Push-Down specimens are tested to clarify the composite action between the concrete block, silence insulator and deckplate. Parameters in this study are the width of T-type bar, the depth of reinforced bar and the thickness of silence insulator. The results from experimental study on longitudinal shear capacity for new-concept composite slabs applied T-type bar, Reinforced bar and Silence insulator are summarized as follows. In test result, the Longitudinal Shear Capacity of the new concept specimen is 2 times excellent than basic specimen with safety. It is expected that applying the proposed composite slab detail at the actual site will provide a significant safety factor in structural aspect of the existing composite slab, and greatly contribute to the improvement capacities of resisting vibration and sound.

• Steel and Composite Structures
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• 제13권6호
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• pp.571-586
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• 2012

The paper addresses some key issues related to the design of composite slabs with cold-formed profiled steel sheets. An experimental programme is first presented, involving six composite slab specimens tested with a view to evaluating Eurocode 4 (EC4) provisions on testing of composite slabs. In four specimens, the EC4-prescribed 5000 load cycles were applied using different load ranges resulting from alternative interpretations of the reference load $W_t$. Although the rationale of the application of cyclic loading is to induce loss of chemical bond between the concrete plate and the steel sheet, no such loss was noted in the tests for either interpretation of the range of load cycles. Using the recorded response of the specimens the values of factors m and k (related to interface shear transfer in the composite slab) were determined for the specific steel sheet used in the tests, on the basis of three alternative interpretations of the related EC4 provisions. The test results confirmed the need for a more unambiguous description of the m-k test and its interpretation in a future edition of the Code, as well as for an increase in the load amplitude range to be used in the cyclic loading tests, to make sure that the intended loss of bond between the concrete slab and the steel sheet is actually reached. The study also included the development of a special-purpose software that facilitates design of composite slabs; a parametric investigation of the importance of m-k values in slab design is presented in the last part of the paper.

• Steel and Composite Structures
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• 제5권4호
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• pp.259-269
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• 2005

Many slab-on-girder bridges around the world are being assessed because they are approaching the end of their anticipated design lives or codes are permitting higher allowable loads. Current analytical techniques assume that the concrete and steel components act independently, typically requiring full-scale load testing to more accurately predict the remaining strength or endurance of the structure. However, many of the load tests carried out on these types of bridges would be unnecessary if the degree of interaction resulting from friction at the steel-concrete interface could be adequately modeled. Experimental testing confirmed that interface friction has a negligible effect on the flexural capacity of a slab-on-girder beam however, it also showed that interface friction is significant under serviceability loading. This has led to the development of an improved analytical technique which is presented in this paper and referred to as the slab-on-girder mixed analysis service load assessment approach.