Tension Stiffening Research Articles

Time-dependent behaviour of RC beams under eccentric combined loads as a unit of beam-column joint assemblies made from normal strength concrete without/with CFRP wraps

The influence of sustained eccentric loads including torsion on the time-dependent behaviour of monolithically framed RC beams into columns is investigated in this paper. The adopted experimental program entails a number of beam-column assemblies tested under sustained concentric and eccentric combined loads (bending, shear, and torsion). The presence of Fibre Reinforced Polymers (FRP) wraps applied to the beam is considered and the time-dependent performance was thoroughly assessed. The outcomes of the experimental program complemented with finite element (F.E.) results illustrated a significant increase in the time-dependent beam’s twisting and deflection levels. The rise in the beam’s time-dependent deflections was quantified in comparison with those predicted according to Eurocode 2. This rise can be explained by the extent of torsional cracks observed, accompanied by high strain levels, resulting from the interaction between combined loads and the time-dependent deformations of concrete. While the FRP wraps considerably improved the time-dependent torsional stiffness compared to the un-strengthened specimens. The numerical models under different loads ratios (torsion to bending-shear ratio) confirmed the role of the level of combined loads and the developed time-dependent cracks of reducing the members’ stiffness and affecting the twisting levels and hence increased the deflection values. A refined approach of the Eurocode 2 modal has been proposed which considers the interaction of combined forces and hence, the developed stresses on the degrees of the loss of tension stiffening.

Experimental Study on the Mechanical Properties and Cracking Characteristics of Bacterial Concrete

Concrete has been used as a construction material for a long period. When the concrete members are exposed to extreme conditions cracks develop. When a crack opens harmful contaminants may enter the concrete matrix. Water may enter through this crack and result in the corrosion of reinforcement bars. Corrosion of the reinforcement bar also results in the formation of cracks. Compressive strength, flexural strength, split tensile strength and permeability are adversely affected by the formation of cracks. Once damaged these structures need to be repaired. Self-healing concrete is an environmentally friendly and cost-effective method for repairing small cracks. An efficient microbial agent for preparing self-healing concrete is the bacillus species. The sample preparation is done by using Bacillus subtilis. The concentration of bacillus opted for the sample preparation is cells per millilitre. The mechanical properties of bacterial concrete are experimentally evaluated and compared with that of conventional concrete. The tension in concrete is usually overlooked while evaluating the strength of reinforced concrete sections because it makes such a small contribution to member strength. Yet it makes a significant contribution to members’ performance under service loads. In this work, tension stiffening of bacterial concrete is experimentally evaluated on concrete prismatic members made of M20 grade concrete reinforced with 8mm and 12mm diameter bars. The direct tension specimen has a cross-sectional dimension of 60 X 60mm and a length of 600mm. The total length of the steel-reinforced specimens, including the bars, is 900 mm. The tension-stiffening properties of bacterial concrete are compared with that of conventional concrete.

Prediction of Strain in Embedded Rebars for RC Member, Application of Hybrid Learning Approach

The aim of this study was to find strains in embedded reinforcement by monitoring surface deformations. Compared with analytical methods, application of the machine learning regression technique imparts a noteworthy reduction in modeling complexity caused by the tension stiffening effect. The present research aimed to achieve a hybrid learning approach for non-contact prediction of embedded strains based on surface deformations monitored by digital image correlation (DIC). However, due to the small training dataset collected by the installed strain gauges, the input dataset was enriched by a semi-empirical equation proposed in a previous study. Therefore, the present study discussed (i) instrumentation by strain gauge and DIC as well as data acquisition and post-processing of the data, accounting for strain gradients on the concrete surface and embedded reinforcement; (ii) input dataset generation for training machine learning regression models approaching hybrid learning; (iii) data regression to predict strains in embedded reinforcement based on monitored surface deformations; and (iv) the results, validation, and post-processing responses to make the method more robust. Finally, the developed model was evaluated through numerous statistical performance measures. The results showed that the proposed method can reasonably predict strain in embedded reinforcement, providing an innovative type of sensing application with highly improved performance.

Modelling of CFRP-Strengthened RC Shear Walls with a Focus on End-Anchor Effects

This study first provides an overview of the development of a novel tube anchor system for the seismic strengthening or repair of reinforced concrete (RC) shear walls with carbon fibre-reinforced polymer (CFRP) sheets. The new anchor system can significantly improve the load transfer mechanism between the CFRP and supporting RC structural elements, resulting in ductile behaviour of the strengthened shear walls with increases of lateral load capacity and ductility by up to 2.6 and 8.3 times, respectively. The study then presents a new finite element modelling technique capable of capturing the complete cyclic response, i.e., from the elastic behaviour to the ultimate collapse of CFRP-strengthened RC shear walls with the newly developed tube anchor system. Two different modelling approaches are proposed to consider the effects of the tube anchor system. Additionally, other important CFRP- and RC-related mechanisms, including CFRP debonding effects, confinement enhancement, tension stiffening, compression softening, and strength and stiffness degradation under cyclic loads, are also considered in the model. By comparing the analytical and experimental results, it is demonstrated that the proposed modelling approach can accurately replicate the complex behaviour of CFRP-strengthened shear walls with a wide range of aspect ratios, from the ductile flexural behaviour of slender walls to the brittle shear failure of squat walls, without requiring detailed modelling of the anchor system.

Cracking behaviour of textile-reinforced concrete with varying concrete cover and textile surface finish

The cracking behaviour of textile-reinforced concrete (TRC) impacts the serviceability and structural integrity of TRC beams. However, textile reinforcement has not yet been standardised and there are numerous available textile reinforcement options. In spite of evidence that the textile properties influence the cracking behaviour of TRC, knowledge of the role of the textile, concrete and geometric parameters on cracking is still limited. This paper investigates a commonly used subset of textile reinforcements, namely epoxy-impregnated textiles with a high yarn count, some of which are prone to induce splitting failure. Through a comprehensive experimental study of 144 uniaxial reinforced concrete tensile tests, the influence of the textile fibre strand geometry and surface finish (plain or sand-coated) on the cracking behaviour was investigated in dependency of the concrete cover thickness. The results show that sand-coating treatment can decrease the transverse crack width to one-third of those observed in analogous plain textile specimens. The geometry of the plain fibre strands, which is affected by the textile fabrication method, also leads to significant differences in the measured crack widths (factor of 2.5). The overall cracking behaviour, however, is decisively influenced by the occurrence of splitting (longitudinal) cracks in the layer of the textile reinforcement, which were observed regardless of the surface treatment for concrete covers thicker than 15 mm. In case of the sand-coated textiles, these splitting cracks initiated immediately after the first main crack and propagated throughout the specimen, which diminished any tension stiffening effect. In the plain textile samples, the cracks led to an excessive spalling of the concrete cover. The results of this study provide a deeper understanding of the cracking behaviour of TRC with epoxy-impregnated textiles and a comprehensive database for further research. This establishes the basis for unified regulations regarding the limit states of TRC structures.

Standardized RC beam tests for modeling the fiber bridging effect in SFRC

Fiber reinforcement is a promising solution to cracking problems and improving the concrete’s structural performance. The residual strength of the cracked concrete can characterize the reinforcement efficiency. However, quantifying the residual performance of steel fiber-reinforced concrete (SFRC) is challenging. The existing methodologies provide empirical formulas for estimating the residual strength using test results of SFRC elements in which a predominant crack governs the mechanical resistance. For instance, the 0.5 mm crack width determines the minimum value considered in the RILEM standard formulas. Thus, the SFRC strength evolution at earlier cracking stages remains unknown. At the same time, such a crack approximation is irrelevant to structural cases when reinforcement bars stimulate the formation of multiple cracks, and the 0.1–0.2 mm crack typically corresponds to the yielding of the steel bars. This study describes an alternative approach for quantifying the average residual stresses in SFRC elements with multiple cracks. It hypothesizes the possibility of separating the mechanical resistance components, corresponding to tension stiffening and fiber bridging effects characteristic of SFRC elements with bar reinforcement, using standardized small-scale specimens to estimate the fiber contribution. The laboratory tests of the plain concrete and SFRC beams with bar reinforcement illustrate the proposed technique. The Rilem standard three-point bending tests and the numerical simulation of full-scale beams verify the analysis’s adequacy. The developed model is suitable for finite element simulations (employing the smeared crack model); the capability of separating the tension stiffening and fiber bridging effects ensures its versatility.

Validated three-dimensional finite element modeling for static behavior of RC tapered columns

Abstract This article aims to simulate the behavior of reinforced concrete (RC) tapered columns subjected to static loads. The experimental data used in the study are from the literature. Two of the simulated columns are slender columns tested under uniaxial eccentric loads. The third one is a short column and was tested concentrically. The concrete damaged plasticity (CDP) model offered in the Abaqus software, which accounts for stiffness degradation of concrete in both compression and tension, was used. The modulus of rupture of concrete and the value of the cracking strain proposed by the Abaqus analysis user’s manual were used as the parameters of tension stiffening. The modified Hognestadʼs model was used for the compressive behavior of concrete. The Static Riks analyses were performed with an activated geometric nonlinearity. The numerical failure load is 100.125, 99.297, and 102.16% of the experimental failure load for Models 1, 2, and 3, respectively. The agreement of the numerical results with the experimental results has confirmed the efficiency of the CDP model to simulate the concrete behavior, and has also revealed the validity of the numerical models.

Linear Concrete Tension Stiffening Model for Reinforced Concrete Elements

Linear expressions for tension stiffening of concrete are nowadays widely used in software packages of structural analysis. Nevertheless, more elaborated expressions of tension stiffening available in the literature have been used successfully in the past. The use of linear approximations is justified since the influence of the tension stiffening effect in the deformation of the structure is small but not negligible. In this sense, linear approximations are simpler and can be accurate enough. However, this linear approximation, in its present form, does not provide good results in terms of deformations at the element level. This paper proposes a linear expression of the tension stiffening supported by the experimental formulation used to predict the flexural behavior of concrete beams. A detailed example is presented.

Unified analysis for tailorable multi-scale fiber reinforced cementitious composites in tension

Fibers applied to reinforce the cementitious matrix exhibit a wide range of scales, from distributed carbon nanomaterials, chopped short fibers to continuous fibrous reinforcements. When a cementitious matrix is jointly toughened by reinforcing fibers at multiple scales, Multi-Scale Fiber Reinforced Cementitious Composite (MSFRC) tailored built on the micromechanics-based approach and bond-slip mechanism is proposed in this study. The composite actions of MSFRC, namely, tension stiffening, ductility enhancing and synergetic effects, are explained within a universal perspective. In addition, a 1-D numerical model using spring elements is developed to simulate the tensile behavior of MSFRC based on the crack band theory, fiber-bridging model and Monte Carlo simulation. The scales, types and contents of reinforcing fibers, interface behavior and stochastic nature can be considered in the model. Finally, it is found that the predicted mechanical response and crack evolution process match well with the experimental results obtained from literatures.

Experimental studies on tensile behavior of reinforced engineered cementitious composite members with double steel rebars

AbstractThis paper investigates the tensile behavior of reinforced engineering cementitious composite (ECC) members. Twelve reinforced ECC members were tested in uniaxial tension. The stress‐average strain curves, failure modes, and the strain of longitudinal reinforcement at selected sections were obtained during testing. The influence of reinforcement ratio on the load resistance and deformation capacity of members was determined. Test results showed that the tensile behavior of reinforced ECC members could be divided into three stages, namely, the elastic stage, the microcracking stage and the major cracking stage. ECC significantly contributed to the load resistance of reinforced ECC members before the formation of major cracks through tension stiffening effect. The load capacity and deformation capacity of reinforced ECC members increased with the increase of reinforcement ratios. For members with ungrooved steel bars, the ultimate load and ultimate strain increased by 130.0% and 115.2% with the reinforcement ratio increased from 1.01% to 2.26%. For members with grooved steel bars, the ultimate load and ultimate strain increased by 123.6% and 98.7% with the reinforcement ratio increased from 0.78% to 2.04%. Based on the test results, the failure mechanism of reinforced ECC members was analyzed and equations for predicting the load capacity of members were proposed. Comparisons between experimental and calculated load capacities suggested that the calculated results were in good agreement with the experimental values. The study on the tensile behavior of reinforced ECC members provides useful results for the design and application of reinforced ECC members.

Effect of polyethylene terephthalate fibres on the structural performance of reinforced concrete beams with openings in the shear region

The provision of transverse openings in the shear region of beams to allow passage of services reduces the cracking and ultimate load capacities of the beams and increases deflection under the openings, especially when the size of the opening exceeds 25 % of the overall beam depth. Strengthening of the pre-planned opening regions by use of special steel reinforcements causes reinforcement congestion and difficulties in compaction, calling for alternative ways of strengthening beams with openings. In this study, concrete material was modified by the use of Polyethylene Terephthalate (PET) fibres produced from waste plastic bottles to improve the tensile properties and hence reduce the cracking around the openings and improve the overall performance of the beams. To evaluate the performance of PET fibres in beams with openings, eight (8) reinforced concrete beams with and without fibres of dimensions (150 × 250 × 2000 mm) were cast with varying opening sizes. The horizontal position of the openings was fixed at 300 mm from the support while the vertical position was maintained at the mid-depth of all beams. This performance was evaluated in terms of ultimate and first cracking loads, mid-span deflections, ductility, crack patterns and failure modes, and strain behavior. Test data showed that incorporating PET fibres in beams with openings resulted in a slight increase in ultimate load of 4.1 % and 5.82 % for 0.25 h and 0.35 h beam opening sizes respectively, beyond which the strength was reduced by 9.57 % for beams with 0.45 h opening size, where h was the overall depth of the beam. The first cracking loads increased by 44.12 %, 48.48 %, and 9.38 % for 0.25 h, 0.35 h, and 0.45 h opening sizes, respectively. In addition, a slight improvement in the ductility of PET fibre beams for all opening sizes was observed. The PET fibre beams exhibited a slight change in the mode of failure from dominant shear failure to combined shear and flexure failure characterized by multiple cracks in the flexure region with minimal spacing. An increase in the concrete compressive and tensile strains accompanied by a reduction in concrete and steel shear strains was observed because of the tension stiffening effects of the fibres. The incorporation of PET fibres, therefore, showed a slight improvement in the ultimate performance of beams with 0.25 h and 0.35 h opening size, with no improvement for the control beam and 0.45 h opening sized beam. However, a significant improvement in the serviceability performance for all PET reinforced beams was observed.

Experimental and analytical investigations on tension stiffening of reinforced engineered cementitious composites members

Experimental and analytical investigations on the performance of reinforced ECC members in tension were studied in this paper through direct tension load. The applied load and elongation of members were measured during testing. The number and width of major cracks in specimens were determined at failure. The influences of the cross-sectional dimension and steel reinforcement diameter on the tension stiffening of members were investigated. Comparisons were made among reinforced ECC members with different cross-sectional dimensions or reinforcement diameters in terms of the cracking load, ultimate load and ultimate strain. Experimental results showed that the load-deformation relationship of reinforced ECC members could be divided into three stages, namely, initial elastic stage, multiple cracking stage and major cracking stage. In addition to experimental tests, an analytical model for the tension stiffening behaviour of reinforced ECC members was proposed. The interaction between ECC and steel reinforcement was considered at different stages in this model. Comparisons with experimental data suggest that the analytical model could accurately predict the relationship between load and deformation of reinforced ECC members. The cracking load obtained by this model is conservative as compared with test data. Based on the validated analytical model, a parametric study was carried out on the effects of reinforcement ratio and bond stress on tension stiffening of reinforced ECC. The direct tension tests and analytical results in this study can be used to predict the load and deformation behaviour of reinforced ECC members in tension.

Discontinuous yielding in bare and embedded reinforcing bars: Implications on the determination of steel and bond shear stresses from strain measurements

Distinct jumps from the yield strain to the strain at the onset of hardening occur in bare reinforcing bar exhibiting a yield plateau once the yield limit is reached. These strain discountinuities known as Lüders bands nucleate at single locations and travel along the bar axis at a constant load. In contrast, no such strain jumps were observed in recent experiments with such reinforcing bars embedded in concrete and instrumented using distributed fibre optical strain sensing (DFOS). Instead, the strain increased gradually at locations where the yield limit was exceeded. This observation, made possible by the high sensing resolution of DFOS, cannot be explained entirely by the known effect of tension stiffening. While bond stresses cause a variation of steel stresses along the bar axis and, hence, indeed prevent Lüders bands from propagating along embedded bars, distinct strain jumps would still be expected at the locations where the yield stress is reached. The different steel stress–strain behaviour is rather attributed to the three-dimensional stress state induced by the locally concentrated bond forces at the bar ribs. These forces presumably (i) cause the direction of maximum shear stress to vary over the bar cross-section, leading to a loss of the macroscopic yield phenomena, and (ii) reduce the nominal yield stress in axial tension. As a consequence of the altered yield behaviour, a simple conversion from strains to stresses using a steel stress-strain relationship derived from uniaxial tensile tests leads to incorrect results for the strain range slightly below the yield limit up to the onset of hardening. These findings are most relevant for experimental studies investigating bond with DFOS, since researchers rely on the validity of the steel material law to derive and validate bond stress-slip relationships.This paper presents the results of the mentioned experiments, discusses the observed differences between bare and embedded reinforcing bars along with potential explanations, and outlines the implications on the determination of steel and bond shear stresses based on strain measurements in reinforcing bars embedded in concrete.

Long-term behaviour of recycled aggregate concrete beams prestressed with carbon fibre-reinforced polymer (CFRP) tendons

The utilisation of recycled aggregate concrete (RAC) is commonly recognised as one of the most effective means to achieve cleaner and sustainable development in civil engineering. To promote the application of RAC, prestressing technique can be employed to overcome the inherent disadvantages of RAC beams associated with poor cracking resistance and large deflections. However, the research on the prestressed RAC beam is quite limited, and no research has been performed on their long-term behaviour. This paper presents a finite element (FE) analysis for investigating the long-term behaviour of RAC beams prestressed with carbon fibre-reinforced polymer (CFRP) tendons considering the effects of concrete creep, concrete shrinkage, tendon relaxation as well as the cracking and tension stiffening of concrete. Based on the principle of superposition, the variations of the stress and strain with time are considered in the numerical analysis using step-by-step method. The FE model is calibrated with the experimental results obtained from the literature. Based on the validated model, a comprehensive parametric study is performed to investigate the effects of the replacement ratio of recycled coarse aggregate (RCA), concrete strength, reinforcement ratio, prestress level, and sustained load level on the long-term behaviour of prestressed RAC beams. The obtained results demonstrate that increasing the prestress load is an effective way to reduce the long-term deflection of RAC beams, and the use of RAC with low RCA replacement ratio is suggested. Besides, the main causes of the long-term deflection and axial shorting of the CFRP prestressed RAC beams are also studied. This research provides a pioneering and insightful study of the long-term behaviour of CFRP prestressed RAC beams. The obtained results demonstrate that the time-dependent effects should be well considered in the design before the prestressed RAC beam is used in practice.

Analytical moment-curvature solutions for generalized textile-reinforced concrete sections

A piecewise linear parametric constitutive model of elastic-plastic-hardening in tension and elastic-plastic in compression is used to develop closed-form solutions for flexural moment-curvature of generalized sections. Brittle matrix composite such as Textile Reinforced Concrete (TRC) is homogenized using three zones of elastic, distributed cracking, and tension stiffening up to the maximum tensile strength. Linear segments of the tensile and compressive constitutive responses are integrated for various states of strain and extended to geometrical structural shapes such as steel W-, T-, and C- sections. The closed-form moment-curvature response is obtained using two independent variables of strain distribution and neutral axis location and extended to obtain the stress distribution, curvature, rotation, and deflection profile of statically determinate load cases using an input strain. The solutions for serviceability-based criteria and limit state parameters such as curvature, rotation, and deflection distribution as a function of the applied load can be obtained. The generalized parametric solutions are applied to the elastic-plastic flexural response of quasi-brittle or ductile beams of structural steel with unique cross-sectional geometries. Case studies of the correlation of tensile and flexural tests of TRC with variables such as types and direction of the weave, number of textile layers, and section geometry are validated. The parametric nature of the formulation offers computational efficiency for applications that address material and shape optimization, as well as serviceability-based flexural design using different limit states.

Time‐dependent elongation and cracking behavior of fiber reinforced concrete tension chords

AbstractThe long‐term (LT) tension stiffening effect in fiber reinforced concrete (FRC) tension chords is investigated in this paper. Six tension tie specimens with varying fiber types (either no fibers, polypropylene, or steel fibers) and reinforcement ratios were subjected to a sustained tensile in‐service load for 560 days. The LT specimens were fitted with gauges to monitor their elongation over the test period. In addition, 12 specimens were subjected to instantaneous loading to capture the entire load‐deformation response of the tension ties, up to and beyond the yielding of the reinforcement. A complete suite of material characterization tests were conducted in conjunction with the tension tie testing. The results from this investigation indicate that the inclusion of the fiber types and dosages adopted in this program improve the short‐term performance with respect to stiffness, tension stiffening, and cracking. Steel fibers improved the LT behavior, while the polypropylene fibers used in this study led to mixed results. Models previously developed by the authors have been shown to describe the behavior with good accuracy.

General Mathematical Model for Analysing the Bending Behaviour of Rectangular Concrete Beams with Steel, Fibre-Reinforced Polymers (FRP) and Hybrid FRP–Steel Reinforcements

The design guidelines available in building codes for steel and fibre reinforced polymer (FRP) reinforced concrete (RC) beams have been developed on the basis of empirical models. While these models are successfully used for practical purposes, they require continuous improvements with more experimental data. This paper aims to develop a general mathematical model derived from the intrinsic material properties of concrete and certain reinforcements to analyse the bending behaviour of reinforced concrete beams. The proposed model takes into account the effects of non-linearity and ductility on the real behaviour of concrete under compression as well as the concrete tension stiffening. The model focused on analysing the flexural behaviour of rectangular steel, FRP and hybrid FRP–steel RC beams, using the moment–curvature relationship. A general static equilibrium equation was developed and mathematically solved with precise methods to establish a moment–curvature relationship. The effective flexural stiffness (EFS) is therefore calculated by the slope of the moment–curvature diagram, and then the load–deflection response is immediately deduced according to the loading conditions. The present model results were compared with numerous test data reported by various researchers. The comparisons reveal a good accuracy for predicting the EFS and load–deflection response for either steel, FRP, and hybrid reinforced concrete beams, with an error average less than 10%.

Synergistic tensile response of reinforced ultra high performance concrete with low fiber contents

From the perspectives of ductility, economic and construction, reinforced ultra high performance concrete (UHPC) structures with low fiber contents have a significant potential in applications. This paper studied the tensile behaviors and damage mechanisms of reinforced UHPC with low fiber contents based on the direct tensile tests accompanied with acoustic emission (AE) detection system. The test results show that the high strength steel bar can prolong the tensile multiple-cracking stage of reinforced UHPC with low fiber contents in some extent at the serviceability stage and further improve its tensile ductility via inducing additional longitudinal cracks at the failure stage. It is found that the low fiber contents and steel bar grades have marginal effect on the tension stiffening at the first cracking of reinforced UHPC. Non-negligible tension stiffening effect still remains at yielding of steel bar and it is more obvious for normal strength steel bar and UHPC with a higher fiber content. The AE weighted peak frequency can identify the tensile damage model of reinforced UHPC with low fiber contents: no internal damage occurs during stage Ⅰ; matrix cracking occurs accompanied by marginal fiber pull-out during stage Ⅱ; matrix cracking and fiber pull-out are dominated during stage III and stage IV, respectively.

Assessment of bond deterioration in corroded RC members incorporating cracking response and tension stiffening

Deterioration of bond between steel reinforcement and concrete due to corrosion significantly affects the durability, strength, and serviceability of reinforced concrete (RC) structures. This paper discusses the effects of reinforcement corrosion on the bond deterioration of RC members through cracking and tension stiffening behaviours. A series of RC members were tested under direct tensile force. A bond reduction model due to the corrosion was proposed by combining the experimental results and available data in the literature. Average widths of tensile crack on the corroded RC members were precisely estimated based on the proposed bond reduction model. Moreover, a simplified numerical model using three-dimensional non-linear finite element (FE) analysis was performed to reproduce the average response of the tensile members. A good agreement of load-concrete strain behaviour was achieved between experimental and analysis results. The constitutive model of concrete including the effect of reinforcement corrosion under tension for FE modelling was discussed. The findings demonstrate the effective evaluation of member responses deteriorated by reinforcement corrosion. Thus, the study will be valuable in improving the assessment of structural durability and performance.

Modeling statically indeterminate reinforced concrete slabs and beams under fire conditions

AbstractEN 1992‐1‐2 generally limits the redistribution of bending moments from the intermediate supports to the span for continuous reinforced concrete slabs and beams in fire conditions to 15%. While higher redistributions are allowed if sufficient rotation capacity is provided, EN 1992‐1‐2 does not indicate how to assess the rotation capacity. However, plastic hinges caused by the rotation demand under fire conditions are highly relevant when predicting the global response and structural safety of a structure (partially) exposed to fire. Rotation capacity is specifically necessary at support regions subjected to negative bending and fire, where concrete in compression undergoes thermal degradation while the tension chord remains close to ambient temperature. This article presents a comprehensive model for the behavior of statically indeterminate members in fire conditions, enabling to estimate whether sufficient rotation capacity is provided. Material properties specified by EN 1992‐1‐2 are applied combined with complementary considerations concerning (i) the biaxial compressive strength of concrete, (ii) strain hardening and limitations of the ultimate strain of reinforcement, as well as (iii) tension stiffening. Tension stiffening detrimentally influences the ductility of the tension chord, limiting the rotation capacity. When comparing predictions obtained by the model to experimental results given in the literature, the correlation is good for the investigated one‐way continuous slabs and beams. However, considerable uncertainty exists regarding the type of concrete aggregate used. Moreover, uncertainties concerning the behavior of concrete under compression and fire conditions are highly relevant for modeling the region of supports with rotational restraint.