Ultimate Moment Capacity Research Articles

Local buckling behaviour of high strength steel tubular beams under moment gradients

AbstractThis paper presents an experimental study into the effect of moment gradients on the local buckling behaviour of hot‐rolled high strength steel square hollow section (SHS) beams. The influence of moment gradients was investigated by testing 20 beam specimens, ranging from Class 2 to Class 4 according to the cross‐section classification limits given in prEN 1993‐1‐1:2020. Both four‐ and three‐point bending loading configurations were considered with varying shear span lengths. The influence of intermediate stiffeners at the loading point was examined by employing two different loading configurations in the three‐point bending tests, achieving fully stiffened or unstiffened conditions. Local geometric imperfections were measured by means of 3D laser scanning, and the displacement and strain fields at critical regions were monitored by digital image correlation (DIC) during testing. It was shown from the tests that specimens subjected to moment gradients exhibited higher ultimate moment capacities than those subjected to uniform moments.

Finite element modeling of assembling rivet-fastened rectangular hollow flange beams in bending

The assembling rivet-fastened rectangular hollow flange beam (ARHFB) is a new type of cold-formed steel beam. The ARHFB section has two rectangular hollow flanges formed by U-shaped and C-shaped components that connected by self-locking rivets. A finite element model is developed to simulate 16 four-point bending experiments. Details of the modeling including finite element meshing, loading and boundary conditions, contact and analysis methods are presented. The accuracy of the developed finite element model is verified by comparing the ultimate moment capacity, applied load versus deflection curves, bending moment versus deflection curves, strain versus deflection curves and failure modes obtained from the tests and the finite element analysis. Based on the validated finite element model, a parametric analysis is carried out to discuss the effects of rivet spacing, section depth, flange thickness, and web thickness on the bending performance of ARHFB. The moment capacities of these sections obtained from the parametric study are compared with predictions from Australia and New Zealand, Chinese design standards for cold-rolled sections and the DSM (Direct Strength Method). It is found that GB50018 can conservatively predict the bearing capacity of ARHFB with a large error, while AS / NZS 4600 and DSM (Direct Strength Method) cannot provide reliable prediction results.

Axial compressive behaviour and physical characteristics of high strength self-compacting geopolymer concrete (HSGC) columns exposed to elevated temperature

The growing demand in the utilization of the cement has increased carbon emissions, necessitating the adoption of new technologies that are eco-friendly. Geopolymer concrete (GC) is a viable alternative to traditional cement-based concrete, with superior mechanical properties and sustainable performance. However, research on the elevated temperature exposure of geopolymer paste, mortar, and concrete is limited, particularly with respect to high-strength and self-compacting geopolymer concrete. This study aims to investigate the performance of high-strength self-compacting geopolymer concrete (HSGC) at room temperature and elevated temperatures up to 1029 ℃. The investigation is carried out consisting of two strength grades: normal strength GC and HSGC. Tests are conducted on both HSGC cube and column specimens to examine the residual compressive strength (CS) and axial compression performance of the concrete before and after exposure to elevated temperature. The fresh physical characteristics of HSGC are examined following EFNARC guidelines. Post-fire performance is analysed through physical observation, surface modification, crack pattern, weight loss (WL), and residual CS of HSGC samples. Load-Moment (P-M) interaction curves are developed to predict the ultimate load and ultimate moment capacity of the HSGC columns before and after exposure to elevated temperature. The ductility of heated and unheated HSGC columns is found to be almost same. Microstructural analysis, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) are performed to examine the internal morphology of the HSGC samples before and after exposure to elevated temperature. Furthermore, a life-cycle assessment (LCA) is conducted to compare the cost of HSGC production with conventional cement-based concrete. The analysis indicates that HSGC emits 6.15% less CO2-e than its counterpart cement-based concrete.

Flexural behavior and bond coefficient of BFRP bar reinforced normal and high strength concrete beams

Basalt fiber-reinforced polymer (BFRP) bars are emerging as potential non-metallic reinforcements for concrete structures due to the wide availability of their raw materials, their environmentally friendly manufacturing process, and their excellent mechanical and durability properties. This paper focuses on the flexural and deflection response of normal and high-strength concrete (HSC) beams reinforced with BFRP bars. A total of fifteen simply supported concrete beams were tested under four-point loading on a flexural span of 2.5 m. The study parameters were the reinforcement ratio, BFRP bar size, concrete strength and bar type (BFRP, GFRP and Steel). The experimental results were compared to ACI 440.1R-15 predictions. The prediction of ultimate moment capacity was in good agreement with the experimental result, while the cracking moment was overestimated. Furthermore, the mid-span deflection was significantly underestimated at service and ultimate loads. Modification in the empirical equations was proposed to enhance the predictions of mid-span deflection at service load. The bond coefficient kb used for predicting the crack width was estimated at 0.89 and 1.12 for BFRP-reinforced normal and high-strength beams.

Grey Wolf Optimization–Aided Cost-Minimization Technique of Reinforced Concrete T-Beam at Ultimate Load

Minimizing construction cost while simultaneously meeting structural requirements has been an important topic. This study addresses the application of grey wolf optimization (GWO) to the cost minimization of T-beams subjected to ultimate loading. Both the objective and constraints functions take the self-weight of T-beams into account. Due to their section modulus, T-beams have a high ultimate bending moment capacity, especially over long spans. The objective function has been split into three subobjectives: concrete, steel, and formwork costs. Standard design constraints were followed. The constraint functions include the nonlinear behavior of concrete and steel. Ten T-beams of varied lengths were evaluated, and corresponding low-cost design solutions were provided. The relationship between the length of the T-beam and the efficiency of GWO was demonstrated. Comparisons between optimal solutions attained and standard design solution demonstrated conclusively that the proposed method typically results in large reductions in the quantity of building materials needed. This method can be easily adaptable to various types of RC frame construction and other building codes.

Behavioral response of reinforced concrete beams with ultra-ductile fiber-reinforced cementitious composite layers – Experiments, models and reinforcement limits

Ultra-ductile fiber-reinforced cementitious composite-reinforced concrete beams (RC-UDFRC) lack well-established bar-reinforcement limits and accurate behavioral modeling. Based on the experimental results obtained in this study, analytical formulae have been presented for calculating bar reinforcement limits for RC-UDFRC beams. A comprehensive numerical method has also been proposed that combines the use of equilibrium conditions, constitutive material models, and finite layers for predicting the entire flexural behavior of RC-UDFRC beams. Results of the study showed that introducing UDFRC into RC beam construction significantly impacted the minimum bar reinforcement requirements. Further, the simplified analytical approach for the ultimate moment capacity of RC-UDFRC beams exhibited reasonable predictability. The proposed model produced relatively accurate curvatures at cracking and ultimate loading with mean error values of 15 and 7%, respectively. Additionally, the proposed numerical method had rational cracking, yielding, and ultimate loading calculations with the mean of the tested-predicted values of 1.08, 1.11, and 0.98, respectively.

Experimental investigation on the behaviour of FRP strengthened square hollow section steel members under monotonic and cyclic loading

Strengthening and rehabilitation of square hollow sections (SHS) are a major concern nowadays as SHS may fail due to higher service loads, fabrication and construction errors, degradation of material over time and adverse effects of the cyclic loading due to earthquakes. In this study, a detailed experimental investigation has been carried out for the implications of using carbon fibre reinforced polymer (CFRP) and glass fibre reinforced polymer (GFRP) as a strengthening measure to mitigate the failure of SHS members under monotonic and cyclic loadings. Strengthened members displayed lower moment degradation and higher moment and energy dissipation capacities and higher stiffness and ductility compared to the bare steel members. Although the amount of CFRP and GFRP fibres were almost equal, CFRP strengthening can result in higher capacity sections due to having higher strength material properties compared to GFRP strengthening. The cyclic responses of the GFRP-strengthened member were close to that of the CFRP-strengthened member and can be more effective for strengthening steel SHS under cyclic flexural loading. The established theoretical model in the current paper can predict reliably the ultimate moment capacities of the strengthened SHS members. This study confirmed that strengthening SHS members with fibre composites will be effective for structures in seismically active regions.

Influence of design parameters on beam-to-column connections of steel storage rack systems

Storage rack systems are the products of cold-formed steel material. Increase in the volume of distant sale in recent years has also increased the importance of logistics and storage industry. In steel storage racks, plug-in beam-end connectors are used to produce boltless and semi-rigid beam-to-column connections. Variability of tab designs for beam-end connector makes it heavily difficult to develop a generalized analytical model. For some typical connectors, several analytical models are available to evaluate the performance of connections. In this study, sixteen beam-to-column connection tests were conducted on a commercially available pallet rack assembly by varying the most effective parameters such as the wall-thickness of the column section, height of the beam, vertical beam position on the connector, and installation of the bolts at connector level among the opening of the column. Being the main goals of this study, failure mechanisms and moment-rotation effects of changing vertical position of the beam on the connector and placing bolts among the opening of the column at the horizontal alignments of the connector, were investigated. These experimental results have shed light on how the ultimate moment capacity, rotational stiffness and rotational ductility values ​​vary by changing these design parameters. In the light of these results, an analytical model has been proposed in order to predict the structural behavior of beam-to-column connections with an acceptable accuracy.

Sustainable construction material: Ultra-high performance fibre reinforced concrete (UHPFRC) for railway bridges in Malaysia

UHPFRC is a new concrete technology being used in many countries including Malaysia. UHPFRC favourable material properties open up new potential for precast options in bridge construction and have been widely used as beams for highway bridges in Malaysia. Nevertheless, PRC beams were preferred despite heavy in weight and large sections although these properties affect the design of the bridge substructure as well the cost of construction. This research is to review the applicability of Grade 140/155 UHPFRC beam for railway bridges in Malaysia. Laboratory tests for mechanical properties of UHPFRC were conducted and results were verified and complied with the French Standard, NF P18-470: 2016. The characteristic cylinder and cube compressive strengths were 151 and 155 MPa while the tensile limit of elasticity, post-cracking tensile strengths and modulus of rupture were 7.8, 8.4 and 24.3 MPa respectively. Structural analysis and design as per NF P18-710: 2016 requirement was then performed for a 15 meter UHPFRC IB650 beam to justify its applicability against a Grade 40/50 PRC U-beam of an existing railway bridge in which the ultimate shear and moment capacities of both beams were compared. The ultimate shear and moment capacities of the 4 numbers of U-beams/deck were 4,092 kN and 13,324 kNm respectively and when compared to UHPFRC IB650 beam, six numbers/deck were required with ultimate shear and moment capacities of 4,836 kN and 14,574 kNm respectively. For durability, the modulus of elasticity and depth of water penetration for UHPFRC were 50.8 GPa and 2mm respectively compared to 34 GPa and 11mm for Grade 40/50 concrete.

Finite element modeling of reinforced concrete beams posttensioned with supplemental unbonded near surface mounted nickel‐titanium‐niobium shape memory alloy wire reinforcement

AbstractA novel posttensioning technique using nickel‐titanium‐niobium (NiTiNb) shape memory alloy (SMA) wires for the repair of reinforced concrete beams was evaluated numerically. A finite element model of a reinforced concrete beam was developed within a damage mechanics framework to simulate concrete cracking and subsequent posttensioning. The predicted yield and ultimate moment capacities of the simulated posttensioned beams were up to 14% less than the corresponding experimental results. Cumulative discrepancies in the assumed material models led to the conservative model results. The effects of concrete tensile damage, SMA reinforcement ratio, SMA‐concrete interaction (bonded vs. unbonded), and the effective prestress on the service and ultimate behavior of the posttensioned beam were evaluated. Partial loss of prestress in the SMA due to elastic shortening of the concrete was insignificant (<3%) because of the relatively low elastic modulus of the SMA. Increasing the SMA reinforcement ratio by three times increased the yield moment of the posttensioned beam by 99%. Reducing the effective SMA prestress to 80% of the initial prestress to account for the possible losses resulted in a decrease in the yield moment by up to 7.8%.

Three-Dimensional Numerical Simulation for Lateral Distortional Buckling Behaviour of Steel-Concrete Composite Beams

Lateral Distortional Buckling (LDB) is a mode of instability in Steel-Concrete Composite (SCC) beams that is yet to be fully understood by the structural engineering research and design community. This work investigated numerical methods to understand the LDB behavior of SCC beams under negative moments that exhibit nonlinear behavior. Focus of the study was to develop and validate 3-Dimensional finite element (FE) models which capture the LDB behavior of SCC beams precisely. Detailed 3-Dimensional FE models of the SCC beams were developed using ABAQUS. For modeling concrete, a nonlinear damage plasticity model was considered. A quad-linear curve was used to describe the stress-stain relationship for the steel beam. The stress-stain relationship for the rebar was described using a bi-linear curve while an elastic perfectly plastic model was assigned to the headed stud shear connectors. Steel hardening behavior was simulated using an isotropic hardening model. The interaction between the concrete slab, steel beam, and studs was described using appropriate interface elements combined under suitable constraints. The FE model’s accuracy was validated by results obtained from previous experiments found in literature together with a brief description of the experiments done by previous researchers to ensure completeness. Validation of the model was done by comparing Moment-Rotation curves obtained from the experimental tests, lateral displacements of the bottom flange along the axial direction and comparison of the failure modes between the numerical model and experimental test specimens. It was observed that the maximum relative error for the ultimate moment capacity of the composite beams from FE analysis and the experimental tests was less than 2% which shows that the FE model was in strong agreement with the experimental results. Accordingly, the numerical model developed herein proves to be capable of accurately representing the LDB phenomenon.

Numerical investigation and design of P-M interaction capacity of CFRP-jacketed hexagonal CFST short beam-columns

Hexagonal Concrete-Filled Steel Tubular (H-CFST) members are now widely recognized by engineers. A serious concern with these columns is the local buckling of thin-walled steel tubes, which Carbon Fiber-Reinforced Polymer (CFRP) sheets offer considerable help in eliminating this troublesome condition. The objective of this study is to evaluate the structural performance of short H-CFST columns stiffened by CFRP strips through nonlinear analysis and numerical simulation. First, the finite element (FE) models were validated against the previous test results, and a close agreement was achieved. Next, an organized parametric study was carried out to investigate the influence of a collection of vital parameters on the strength of the columns. The ultimate eccentric loads of the columns were computed, and the results were plotted as load-moment (P-M) interaction diagrams. The confining contact stress methodology between the steel tube and the concrete infill was in depth discussed, and it was found that the stress concentration is greater in CFRP-jacketed H-CFST columns than in bare ones, and its value is greatest in the corners. Based on the parametric study within the considered geometric and material ranges, using CFRP sheets effectively improves the confinement effect of steel tubes to the core concrete and enhances the strength of the columns by up to 35%. However, by using fully-wrapped CFRP layers, the columns could handle a maximum of 55% more load-carrying capacity. Finally, a modified design formula based on a unified theory was suggested to estimate the ultimate load and bending moment capacity of H-CFST short columns under eccentric loading.

Structural Performance of Ferrocement Beams Incorporating Longitudinal Hole Filled with Lightweight Concrete

In this study, 10 ferroconcrete concrete (FC) beams with lightweight cores reinforced with welded steel mesh as a shear reinforcement were evaluated under three-point bending tests along with two conventionally normal-weight concrete (NWC) beams. Expanded polystyrene and lightweight aerated autoclaved brick wastes were used to create lightweight core concrete. The main factors include the type of lightweight concrete used for the core, beam concrete type, the form and number of holes, the existing steel mesh fabric, the hollow, and the hole placement. This study was done on the tested beams' ductility index, failure modes, first cracking loads and associated deflections, and ultimate loads besides corresponding deflections. Experimental results showed that the use of FC, various filling materials, and welded steel meshes in place of traditional stirrups enhanced the ultimate load by 36.6–107.3%, the ultimate deflection by 6–272%, and the ductility by 89–1155% when referenced to a control NWC beam. When the holing ratio increased from 10 to 20%, the ductility of FC beams was enhanced by 307.7%. Proposed equations were developed to predict the ultimate load and bending moment capacity of FC beams while taking into account the compressive strength of the beam body and filling material, the holing ratio, the tensile reinforcement ratio, and the volume fraction of the steel mesh.

One pre-stressed methodology named as swelling-fit for binderless dowels joint of wood

One methodology of binderless joint by swelling of dowels with very low moisture content to obtain pre-stress for fast-growing timber was proposed in this paper. The results showed that performance of binderless joint after 48 h conditioning was close to traditional glued-joint, that is 31.5 N·m for ultimate bending moment capacity and 1743.4 N for maximum withdrawing force of two-pin joint. Clear densification of intersection between dowels and poplar beams was observed from micro-structure analysis. The theoretical model to predict the maximum withdrawal force of pre-stressed joint was setup, which is in coincidence with test results.

Estimation of blast-induced peak response of concrete-filled double-skin tube columns by intelligence-based technique

This paper aims to predict the peak response of concrete-filled steel tubes (CFSTs) under blast loads using regression-based machine learning (ML) algorithms considering the variability of input parameters. Twelve regression metrics that are commonly used are utilized to evaluate and compare the efficiency and effectiveness of the proposed ML models. The Monte Carlo approach is used to propagate the variability in the input space to the predicted output. The results showed that the optimal method varies with perspectives. The XGBoost algorithm has the highest final score, and the SVM algorithm exhibits the highest total score for standard deviation. Furthermore, the confidence interval increases with the peak response, and the single model presents a higher accuracy in predicting large displacements. However, ensemble models do the opposite. Sensitivity and uncertainty analyses are performed, indicating that the scaled distance, section size and ultimate moment capacity exhibit the highest contribution to the peak response of the CFST. Finally, a simple formula is developed based on the MLP model, which can cover three input parameters. The findings of this paper can be used for computer-aided dynamic response design of CFST columns subjected to blast loads.

Experimental investigation on flexural performance of T-joint concrete-filled steel tube with PBL

T-joint concrete filled-steel tube (CFST) members are widely used in many modern structures. The performance of T-joint CFST is studied as the brace is under axial compressive load and chord bends in this paper. A total of eight specimens were designed and manufactured, and FE models were built by ANSYS. The effect of different parameters, including the brace-chord width ratio, the brace-chord thickness ratio, the influence of the PBL, the thickness of the stiffener, the opening diameter and opening space of the PBL, the material strength, and the number and welding position of stiffeners, on the performance of T-joint CFST were investigated through experimental and numerical studies. A criterion for determining when the T-joint CFST with PBL reaches the ultimate bearing capacity is presented. The calculation method in this paper for ultimate moment capacity is derived based on the limit balance theory. The method considering the reinforcement of the brace on the upper flange of the chord, the confinement effect of the steel tube on concrete, and the plastic stress distribution of the steel tube is in better agreement with the test and FE analysis. The results show that the proposed method can well predict the ultimate moment capacity of T-joint CFST, while the method in DBJ is more conservative.

Classification system for inter-modular connections in non-sway corner-supported steel modular buildings

The main difference between the structural design of corner-supported modular buildings with their conventional counterparts lies in the design of their connections. This is because of the different configurations and lack of continuity in joints, resulting in a complex boundary condition for predicting the behaviour of these structures. Because of the ever-increasing demand for building construction using these systems, and a relatively large variety of modular connection types being used in practice, it is of paramount importance to provide criteria ensuring the safety and predictability of the stability performance of these structures. This paper proposes a classification system for horizontal and vertical inter-connections in non-sway frames in terms of stiffness and strength for their rotational components. From the stiffness point of view, the boundaries between rigid and semi-rigid zones are identified and formulated with respect to the variation of relative bending stiffness ratios of elements in joints, such as beams, columns, and connections. Two performance criteria are considered for the classification of inter-modular connections in non-sway corner-supported modular buildings: (i) buckling criterion, where general governing equations for buckling analysis are derived for an idealised and simplified model of braced frame corner-supported modular steel building to classify inter-connections based on the ultimate limit state; and (ii) displacement/drift criterion, for which parametric modelling is conducted using OpenSees for classification based on serviceability limit state. From the strength point of view, the inter-connections are classified into three categories namely, fully-strength, partially-strength, and nominally-pinned based on their ultimate moment capacity. The results are then verified in a case study through the use of data for some existing modular inter-connections, from the literature. Finally, based on the findings of this study, some recommendations for the design of inter-modular connections in non-sway corner-supported modular buildings are presented.

Recycled concrete beams subjected to combined reinforcement corrosion and static pre-loading

To investigate the flexural behavioural characteristics of recycled concrete beams under the combined action of steel corrosion and static pre-loading, 12 recycled concrete beam specimens, encompassing a combination of three recycled coarse aggregate (RCA) replacement ratios (0, 50 and 100%) and four static pre-load levels expressed as ratio of the ultimate moment capacity (0, 0.2, 0.4 and 0.6), were prepared for accelerated corrosion test and four-point bending test. The test results indicated that under a given RCA replacement ratio of the beams, the maximum width of corrosion-induced longitudinal cracks exhibited a linear relationship with the corresponding corrosion depth of longitudinal tension reinforcement. For the beams with 50% RCA replacement ratio, when the applied static pre-load level increased from 0 to 0.6, the ultimate load and ultimate deflection reduced by 10.4% and 21.2%, respectively, whereas for the beams with 100% RCA replacement ratio, the corresponding reduction in ultimate load and ultimate deflection were respectively 8.9% and 35.5%. Theoretical degradation models for the ultimate moment capacity and yield moment capacity of corroded beams were proposed, whereby the analytical values were in good agreement with the experimental values. This study provides useful reference for practical analysis of recycled concrete beams, which promote sustainable concrete construction.

Influence of anchor design parameters on flexural performance of hybrid bonded-fiber reinforced polymer strengthened reinforced concrete beams

Strengthening concrete structures using adhesively bonded fiber-reinforced polymer (FRP) has been demonstrated as an effective method to improve the structural capacity. However, premature debonding of FRP material has limited the application of this technique. A number of anchorage methods have been proposed to enhance the bond performance, among which the hybrid bonded FRP (HB-FRP) has appeared to be more attractive as it can provide adhesive bond, frictional bond and dowel action. Previous studies have reported that the HB-FRP technique can considerably improve the bond strength and the flexural capacity of the strengthened beam. Yet, the influence of some key parameters on the flexural performance of the strengthened member is still not completely clear, and an accurate design method that can account for these parameters is not available for estimating the ultimate load capacity. In this paper, an experimental study was conducted on the HB-FRP strengthened beams to investigate the effects of anchoring pressure, anchor spacing, anchor distribution pattern, and FRP bonding mode. The test results indicate that the ultimate load-carrying capacity of the HB-FRP retrofitted member can be enhanced by increasing the anchorage pressure or decreasing the anchor spacing provided that the retrofitted beam fails by FRP debonding. The anchor distribution pattern has negligible influence on the flexural strength of the strengthened member, but uniform distribution of anchors along the bond length can yield higher flexural stiffness than the end anchoring approach. In addition, different FRP bonding mode can cause various strengthening mechanism in the HB-FRP system, leading to distinct flexural behavior of the retrofitted member. The dowel action of the anchor is suggested to be released by means of unbonding the FRP with the steel cap plate of the anchor since it may induce premature brittle anchorage failure. Based on the test results, a modified model is proposed for predicting the adhesive bond strength in HB-FRP system, in which a new parameter, referred to as spacing coefficient, is introduced to quantify the influence of the anchor spacing. Lastly, a theoretical model is developed in this study to design the ultimate moment capacity of the HB-FRP strengthened beam. A good correlation is achieved between the model predictions and the experimental results.

Flexural Behavior of GBFS-Based Geopolymer-Reinforced Concrete Beams

Geopolymer concrete (GC) is an emerging alternative construction material due to it being eco-friendly in production with considerably low carbon emissions. Despite being an alternative material, the structural behavior of GC is a rarely studied subject in the literature. The studies concerning the mechanical behavior of structural members made from GC have established the foundations of its practical usability. The current structural codes are exclusively for ordinary Portland cement concrete (OPCC), and the utilization of these for GC constitutes an open question. In this study, 12 GC beams with different shear span-to-effective depth ratios of 2.5, 3.5 and 4.5 were manufactured and tested in a three-point bending test setup. The effect of the shear reinforcement ratio was also taken into account (0, 0.34, 0.45 and 0.67%). The results were compared with the predictive capabilities of four structural codes and two equations in the literature (all for OPCC). In addition, comparisons were made with a very limited number of studies, which included predictive tools for the strength of GC. All specimens’ cracking moments were calculated with flexural tensile strength predictions and compared with experimental cracking moments. Moreover, particularly for the beams that failed in flexure, the ultimate bending moments were compared with the predictions of two structural codes for OPCC. It was observed that the best predictions of the cracking moment could be made by the equation of Diaz-Loya et al. (2011), which resulted in the lowest coefficient of variation (COV) and consistently predicted on the safe side, whereas, even with a lower COV, EC2 consistently overestimated the cracking moment. For the ultimate moment capacity, it was observed that both ACI318 (2019) and TS500 (2000) delivered relatively good predictions and could be employed confidently.