Steel-concrete Composite Slabs Research Articles

BOND STRENGTH OF STEEL-CONCRETE COMPOSITE ELEMENTS USING A CEMENTITIOUS ADHESIVE

Steel-concrete composite slabs have been used for bridge deck construction in Japan because of several advantages, e.g., safety construction and high fatigue durability. On the other hand, these slabs may cause negative influences such as overweight, increasing costs and low constructability, due to many mechanical shear connectors. The quantities of shear connectors may be reduced by gluing steel-plate and concrete with a cementitious adhesive. The present study aims at examining shear bond strength and quantifying the dispersion of the strength. To investigate the dispersion, a double-lap shear test is conducted, in addition to a simple direct shear test, to examine surface treatment. A Monte Carlo Simulation using the Weibull distribution of the strength is performed to evaluate the effect of dispersion. The simulation implies that the shear stress due to the traffic load may be negligible, indicating the applicability of the composite system for highway bridge decks.

Comments concerning crack width calculation in joints of steel-concrete composite slabs

In this paper some aspects of the calculation of the width of cracks in joints of steel-concrete composite slabs are reported. The code concerning design of composite steel and concrete structures for the calculation of crack widths refers to the code of reinforced concrete structures. The application of the formula, which takes into account „tension stiffening”, seems to lead to surprising results - for the elements with small reinforcement ratio, the obtained stress is much greater than the stress calculated in classical way i.e. without tension stiffening. The authors present the derivation of this formula - the result corresponds to the formula in the code but in the paper an additional case is taken into account. Furthermore, the authors suggest to consider two types of areas as in the RC code. Type D (D from "discontinuity") should be analyzed in the close surrounding of the column and type B (B from Bernoulli) areas at some distance from the column.

Shear Tests of Composite Slabs, Experimental and Numerical Investigation

Composite slab is being used for horizontal structures. The sheeting can serve as a permanent formwork and no additional reinforcement can be required. The slabs are then fast and easy assemble construction which can be effectively used in reconstructions. One of the meanings to assure composite action of composite steel-concrete slabs is prepressed embossments. Its main disadvantage is that the design of a new type of sheeting requires expensive and time consuming large-scale laboratory testing which hamper its widespread commercial usage. Small-scale shear tests present a less expensive alternative to the large-scale tests but its results cannot be simply used for the design of the whole slab. The results from small-scale tests with different options are compared in this paper. Also a possibility of contribution of FE simulation results to the small-scale tests usage is investigated.

An experimental study on the ultimate behaviour of simply-supported post-tensioned composite slabs

Post-tensioned composite steel-concrete slabs consist of thin-walled profiled steel sheeting, post-tensioned strands and concrete. This paper presents the preparation and results of two ultimate test series aimed at evaluating the contribution of the profiled sheeting on the load carrying capacity of this form of construction, and whether this is affected by time effects. For this purpose, six samples were prepared and tested to failure in a simply-supported static configuration by means of two transverse line loads applied near the mid-span. These consisted of two post-tensioned solid slab and four post-tensioned composite ones cast using Stramit Condeck HP® and Stramit PrimeForm® profiled sheeting. The flexural strengths observed for the composite specimens prepared with Condeck HP and PrimeForm profiles were in average 77% and 20% greater, respectively, than the moment capacity of the post-tensioned solid slab counterpart. These values did not appear to be affected by time effects for the material and geometric properties considered in this study. All samples exhibited a ductile response and all tests were terminated due to concrete crushing. A theoretical model was proposed to account for the partial shear connection behaviour of the composite slabs. The model was then applied to evaluate the influence of different geometric and material parameters on the moment capacity calculated for different post-tensioned composite slabs. It is expected that further comparisons with experimental results need to be carried out to properly validate its adequacy for use in routine design.

Investigations on Efficiently Interfaced Steel Concrete Composite Deck Slabs

The strength of the composite deck slab depends mainly on the longitudinal shear transfer mechanism at the interface between steel and concrete. The bond strength developed by the cement paste is weak and causes premature failure of composite deck slab. This deficiency is effectively overcame by a shear transferring mechanism in the form of mechanical interlock through indentations, embossments, or fastening studs. Development of embossment patterns requires an advanced technology which makes the deck profile expensive. Fastening studs by welding weakens the joint strength and also escalates the cost. The present investigation is attempted to arrive at a better, simple interface mechanism. Three types of mechanical connector schemes are identified and investigated experimentally. All of the three shear connector schemes exhibited full shear interaction with negligible slip. The strength and stiffness of the composite slabs with shear connectors are superior about one and half time compared to these of the conventional reinforced concrete slabs and about twice compared to these of composite slabs without mechanical shear connectors. The scheme2 and scheme3 shear connector mechanisms integrate deck webs and improve strength and stiffness of the deck, which can effectively reduce the cost of formworks and supports efficiently.

Long-term behaviour of simply-supported post-tensioned composite slabs

Post-tensioned composite steel-concrete slabs represent an economical form of construction commonly used in Australia. This paper presents three full-scale tests aimed at the evaluation of the influence of the steel deck on the time-dependent response. These consisted of one post-tensioned solid slab and two post-tensioned composite ones using Stramit Condeck HP® and Stramit PrimeForm® profiled sheeting. These samples were cast at the same time in a simply-supported static configuration. Long-term deformations were monitored for a period of 239days while the samples were subjected to their own sustained self-weight and to the development of shrinkage. Standard tests were carried out to obtain the material properties of the components forming the cross-section. In the case of the composite samples, a non-uniform shrinkage distribution developed over time through the slab thickness due to the presence of the steel deck which prevented moisture egress to occur from its underside. For this purpose, separate concrete specimens were prepared and used to monitor the development of this shrinkage gradient. A theoretical model was developed to account for the time-dependent behaviour of post-tensioned composite slabs with particular attention devoted to the development of the non-uniform shrinkage component. Comparisons between numerical results and experimental measurements showed good agreement, highlighting the importance of considering the non-uniform shrinkage profile for an adequate prediction of the deflections induced by shrinkage. It is expected that further comparisons with experimental results need to be carried out to properly validate the adequacy of the proposed approach for its use in routine design.

Numerical analysis of partially fire protected composite slabs

The paper presents a numerical investigation, done with the computer program SAFIR, in order to obtain simpler finite element models for representing the behaviour of the partially protected composite steel concrete slabs in fire situations, considering the membrane action. Appropriate understanding and modelling of the particular behaviour of composite slabs allows a safe approach, but also substantial savings on the thermal insulation that has to be applied on the underlying steel structure. The influence of some critical parameters on the behaviour and fire resistance of composite slabs such as the amount of reinforcing steel, the thickness of the slab and the edge conditions is also highlighted. The results of the numerical analyses are compared with the results of three full scale fire tests on composite slabs that have been performed in recent years.

Time-dependent Stiffness of Cracked Reinforced and Composite Concrete Slabs

The effects of creep and shrinkage on the time-dependent behaviour of reinforced concrete and composite steel-concrete slabs are discussed and procedures for the prediction of the long-term deflection are presented. The time-dependent deformations caused by creep and shrinkage are modelled using tractable formulations developed using the age-adjusted effective modulus method of analysis. The procedure includes the time varying nature of tension stiffening and the effects of time-dependent shrinkage-induce cracking. Sample calculations are provided. The methods are validated against a range of test data and are shown to provide reliable estimates of in-service deformations.

Development of Composite Steel Girder and Concrete Slab Method for Renovation of Existing Steel Railway Bridges

Over half the existing steel railway bridges in Japan have been in service for more than seventy years. Some of these bridges have severe problems including corrosion of the upper flange, fatigue and noise emissions. In this study, a method is proposed for the structural improvement of existing railway steel bridges through installing concrete slabs on existing steel girders. This method improves the load-bearing capacity of the bridges, extends their serviceable life, and reduces noise emissions. Feasibility studies for ease of application of the composite girders were made and the proposed method was verified to ensure it could be completed within the tight allocated time schedules. Furthermore we found through loading tests that the proposed method to produce composite girders also strengthened and increased the stiffness of the girders.

Study on nondestructive testing for steel-concrete composite slab by infrared thermography technology

Study on nondestructive testing for steel-concrete composite slab by infrared thermography technology

Finite Element Analysis on Contact Surface Slip of Profiled Steel Sheet and Composite Slab

In order to evaluate correctly the load-bearing performance of the prestressed profiled steel sheet composite slab，according to actual loading conditions, finite element model of the prestressed profiled steel sheet and concrete composite slab is established. Numerical simulation is made to the slip of the prestressed composite slab. The calculation results show that the slip of the prestressed composite slab at ultimate status will be gradually reduced with the improvement of the concrete strength. When increasing the prestress, the slip value at ultimate status will be less reduced and increasing the thickness of the concrete can reduce the slip value at ultimate status, the deformation of the prestressed composite slab will be increased by over 10% when considering the slip of the bonding surface.

Damage Mechanics Model for Fracture Process of Steel-Concrete Composite Slabs

Composite slab construction using permanent cold-formed steel decking has become one of the most economical and industrialized forms of flooring systems in modern building structures. Structural performance of the composite slab is affected directly by the horizontal shear bond phenomenon at steel-concrete interface layer. This study utilizes 3D nonlinear finite element quasi-static analysis technique to analyze the shear bond damage and fracture mechanics of the composite slabs. Fracture by opening and sliding modes of the plain concrete over the corrugated steel decking had been modeled with concrete damaged plasticity model available in ABAQUS/Explicit module. The horizontal shear bond was simulated with cohesive element. Cohesive fracture properties such as fracture energy and initiation stress were derived from horizontal shear bond stress versus end slip curves. These curves were extracted from bending tests of narrow width composite slab specimens. Results of the numerical analyses match the experimental results accurately. This study demonstrated that the proposed finite element model and analysis procedure can predict the behavior of composite slabs accurately. The procedure can be used as a cheaper alternative to experimental work for investigating the ultimate strength and actual fracture and damage behavior of steel-concrete composite slab systems.

Experimental and Numerical Investigation of Composite Action of Steel Concrete Slab

Thin-walled cold formed corrugated steel sheet with embossments, used in composite steel concrete slab, is a modern and effective construction. The steel sheet is used as a permanent formwork and as a load bearing member after hardening of concrete as well. The prestressed embossments are crucial to ensure a composite action. However, its load bearing capacity is influenced by many factors and it is not possible to be determined without using expensive and time consuming tests of the whole slab in laboratory. This paper is focused on composite action using this type of shear connection and its behaviour under different types of loading.Four-point bending tests and vacuum tests were performed on the whole span slab. Additional small-scale shear test help us to understand the shear behaviour of thin-walled steel sheet in ultimate limit state. The data from the tests make possible to set up and calibrate numerical models. These models can then facilitate pointing out the main factors which influence the load bearing capacity of this type of structure.

Finite Element Analysis on Profiled Steel Sheet and Concrete Composite Slab

This paper adopts the ANSYS software to establish the profiled steel sheet and concrete composite slab finite element model. Numerical simulation is made to the composite slab in the whole process from initial loading to loading failure with reasonable Stimulation material and constitutive relations. The result of the calculation shows that promoting the strength of the concrete can largely promote the bearing capacity of the concrete, and the influence of the strength grade of the profiled steel sheet to the bearing capacity of the composite slab is smaller. The experimental result and test result accord well, testifying the reasonability of the established finite element and provide new method and way for simulating the load bearing process of composite slab.

Carrying Capacity Calculation of Externally Prestressed Profiled Steel Sheet Composite Slab

According to the structural features and actual load carrying status of externally prestressed profiled steel sheet composite slab, in consideration of the deformation of the whole prestressed structure, the prestressed incremental calculation formula is established with force method and the prestressed incremental calculation formulas for arranging reinforcements in straight line or fold line with deviators; according to the positions of neutral axis, the stress-strain of externally pre-stressed profiled steel sheet and concrete composite slab section is analyzed so as to derive the calculation formulas for the elasticity bending bearing capacity and ultimate bending bearing capacity of the externally prestressed profiled steel sheet composite slab.

A Computational Simulation for the Damage Mechanism of Steel-Concrete Composite Slabs under High Cycle Fatigue Loads

This paper investigates the failure mode and the damage mechanism of steel-concrete composite slabs under high cycle fatigue loads by using three-dimensional nonlinear finite element analysis. The applicability of the simulation system, which was originally developed for reinforced concrete slabs, is extended to the steel-concrete composites with the proposed interface element, and experimentally verified with fatigue loading tests for bridge decks. The computed midspan deflection of composite slabs shows a fair agreement with data obtained from the experiment, and the horizontally induced cracking observed in reality is properly reproduced by the computational simulation. Finally, the authors predict the ultimate state at which the upper concrete layer separated by horizontal cracks fails in compression fatigue, and the corresponding S-N diagram is computationally predicted for the future discussion.

Kompozitinių plienbetoninių plokščių, armuotų plieniniu plaušu, savybių tyrimas

Nagrinėjama plieninio plaušo įtaka kompozitinių plienbetoninių plokščių stiprumui ir standumui veikiant statinei trumpalaikei apkrovai. Bandiniams panaudoti „kregždės uodegos“ tipo plieniniai lakštai ir plieniniu plaušu armuotas betonas. Iš viso buvo pagamintos keturios plokštės. Siekiant nustatyti plieninio plaušo įtaką kompozitinių plokščių stiprumui ir standumui, atliktas eksperimentinis tyrimas. Eksperimentinių bandymų metu buvo matuojamos skersinės, išilginės, šlyties deformacijos ir įlinkiai. Bandymų rezultatai parodė, kad plieninio plaušo naudojimas kompozitinėse plokštėse yra efektyvus: laikomoji galia yra 20–24 % didesnė ir įlinkių reikšmės, veikiant 0,6MR (čia MR lenkimo momentas, kuriam veikiant plokštės suyra) apkrovai, yra 16–18 % mažesnės už plokščių su įprastu betonu.

Perfobond Rib 전단연결재를 사용한 실험체의 전단강도 분석

본 연구의 목적은 직접전단응력 및 휨 전단응력의 비교분석을 통하여 Perfobond Rib 전단연결재를 사용한 구조물의 하중방향에 따른 전단응력 분석이다. 직접전단응력 분석을 위해서 5개의 변수로 Perfobond Rib 전단연결재 실험체 5개를 제작하고 Push-out Test를 실시하였다. 실험 후 Perfobond Rib 전단연결재의 전단저항 메커니즘을 규명하고, 직접전단응력에 영향을 미치는 주요 인자를 바탕으로 직접전단력을 산출할 수 있는 제안식을 제시하였다. 또한 휨 전단응력의 분석을 위해 강-콘크리트 합성 바닥판 실험체를 제작하고 정적 휨실험을 실시하였다. 정적 휨실험을 바탕으로 휨 거동특성을 분석하고 휨 전단응력을 계산하였다. 직접전단응력과 EN 1994-1-1을 통해 계산된 휨 전단응력을 비교하여 하중방향에 따른 전단저항응력에 대해서 분석을 하였다. The objective of this study which it sees direct shear stress and comparative analysis of flexural shear stress leads and it is a shear stress analysis which it follows in load direction of the structure which uses Perfobond Rib shear connectors. To analyze direct shear stress, five Perfobond Rib shear connect experiments were fabricated with five variables and conducted Push-out Tests. After experiments, mechanism of Perfobond Rib shear connector was examined and direct shear formula was proposed based on primary factors which influence direct shear stress. Also, for the analysis of flexural shear steel-concrete composite slab specimens were fabricated and static flexural test. Based on the static flexural test it analyzed the flexural behavior and the flexural shear stress it calculated. Direct shear stress and EN 1994-1-1 to lead and be calculated, it compared the flexural shear stress and it analyzed in about the shear resistance stress which it follows in load direction.

Local Stress Behavior around Welded Joint of Angle Shape Shear Connector used in Steel-Concrete Composite Slab

Local Stress Behavior around Welded Joint of Angle Shape Shear Connector used in Steel-Concrete Composite Slab

Shrinkage Deformations of Composite Slabs with Open Trapezoidal Sheeting

Composite steel-concrete slabs that have integral steel shuttering at the soffit of a reinforced concrete slab are commonplace in building infrastructure. Inevitable shrinkage of the concrete represents an indirect (or non-mechanical) strain that results in deformations of the composite slab, resulting in long-term effects in which creep of the concrete also plays a role. Because the impervious steel sheeting prevents moisture egress at the slab soffit whereas at the top of the slab such moisture egress can occur, there is a variation of the shrinkage strain through the depth of the slab, resulting in warping-type deformations. In addition, the composite action between the steel and concrete results in partial shear interaction between these elements, and this interacts with the shrinkage response. Surprisingly little appears in the published literature on rational modelling of the behaviour of composite slabs incorporating partial interaction that are subjected to shrinkage straining, despite its practical importance and significance. Based on fundamental principles of mechanics, a theoretical model of this shrinkage behaviour that includes partial interaction is developed, and prescriptive equations are derived. These may be used to assess the deflections and stresses in the concrete due to restrained shrinkage which may lead to cracking of the slab. It is also shown that the two effects of partial interaction and shrinkage straining counteract each other when slab deflections are considered.