Load-displacement Response Research Articles

Lateral load-displacement response of flexure-dominant concrete-encased steel columns based on ASCE/SEI 41

Concrete-encased steel (CES) column, in which structural steel is encased in an RC section, is widely used in high-rise or heavily-loaded structures due to its great load-carrying capacity, rigidity, and durability. Nevertheless, the development of performance-based seismic design is still insufficient for CES structures, especially for evaluating the lateral load-displacement relationship. As a commonly-used performance-based seismic design (PBSD) guidance, current ASCE/SEI 41 guides global engineers to conduct the seismic evaluation of RC, steel, masonry, and timber structures. Nevertheless, ASCE/SEI 41 fails to give the modeling parameters for CES members owing to insufficient research concerning the steel-concrete interaction. In this paper, a lateral load-displacement curve for flexure-dominant CES columns under a nonlinear static procedure is proposed based on the provisions of RC members in the current ASCE/SEI 41. In the proposed curve, different constitutive laws are applied to consider different confinement of concrete; the slip between the structural steel and surrounding concrete is considered by reduced lateral stiffness; meanwhile, the end rotation caused by the bar-slip in RC is also taken into account to simulate the lateral behavior better. With a detailed calculation procedure, a comparison with experimental results of 42 CES columns in different references is reported to verify the applicability of the proposed curve. It can be concluded that the proposed curve can produce reasonable predictions of cracking load, cracking displacement, yield load, yield displacement, peak displacement, and strength degradation of flexure-dominant CES columns, leading to a feasible way to evaluate the lateral response of CES columns in practical design.

Foreword to the special issue on new developments in structural stability.

Foreword to the special issue on new developments in structural stability.

Modeling Electric Vehicle’s Battery Module using Computational Homogenization Approach

Numerical simulations of heterogeneous structures like battery modules of electric vehicles are challenging due to the various length scales involved in it. Even with the latest computing technology, it is impossible to simulate the crash scene of the full vehicle resolving all length scales. Such hurdles have prevented manufacturers to understand the mechanical response of battery packs in vehicle crash scenarios. In this work, the problem of multiple length scales was solved using the RVE technique based on homogenization theory. An appropriate representative volume element was identified, and a 3D FE model was developed. Classical first-order boundary conditions were used in this research work. The RVE was subjected to several macroscopic deformations, and its response was obtained. The homogenized material properties were computed from the obtained responses, and a material model available in LS-Dyna’s material library was selected and calibrated to describe the nonlinear multiaxial behavior of the homogenized battery module at the macroscale. For validation, the USABC Crush and Drop Tests were simulated for the detailed and homogenized battery modules. The main output of this research is a robust and computationally efficient tool enabling satisfactory integration of a battery pack model to the vehicle for crash simulations, eliminating the need to simulate micro details at macro length scales. This approach significantly reduced the computational cost. For example, for a Drop Test simulation, the homogenized model reduced the simulation time from 40 hours (detailed model) to about 3 minutes, while maintaining a high precision ( R 2 = 0.9871 ) in predicting the load-displacement response. The system level modeling will enable the stakeholders to perform efficient optimization and safety evaluation for full-scale crashworthiness of electric vehicles.

An experimental study on the interfacial bonding performance of horizontally embedded CFRP strips to concrete

The near-surface mounted (NSM) carbon fiber-reinforced polymer (CFRP) strengthening method has a good efficiency in regard to strengthening aging or damaged concrete bridges. To prevent the end debonding failure of NSM CFRP-strengthened beams and simplify the construction, the authors propose a near-end enhanced embedded (NEEE) CFRP strengthening method. In this method, the CFRP strips are horizontally embedded in the grooves that are prefabricated on the surface of concrete structures. To investigate the interfacial bonding performance of the horizontally embedded CFRP strips, a total of 17 single-lap shear test (SST) specimens are fabricated to study the failure mode, ultimate capacity, load–displacement response, and distribution of interfacial shear stress. Moreover, the effects of the groove width, groove depth, embedding depth of horizontal CFRP strips, and concrete strength are analyzed and discussed. Then, a local bond-slip model with characteristic parameters (i.e., the maximum bond stress, critical slip, and residual bond stress) is proposed to describe the interfacial bond behavior. These characteristic parameters are independently determined according to the experimental results of each specimen. Furthermore, a generalized bond-slip model is proposed and validated, which can directly predict the characteristic parameters according to the geometry and material properties of SST specimens.

Investigation on axial compressive behavior of pentagonal section steel-reinforced concrete columns

Special-shaped steel-reinforced concrete (SRC) columns have been widely used in high-rise buildings, while research on the axial compressive performance of special-shaped SRC columns is limited. To address this issue, four pentagonal section SRC columns based on an actual engineering project were designed and tested to examine the failure mode, axial load-displacement response, bearing capacity, ductility, and restoration capacity. The effects of the steel section structure and concrete strength on the axial compressive performance of the pentagonal section SRC columns were investigated. The test results showed that the pentagonal section SRC columns exhibited great axial compressive performance, the SRC columns with distributed rectangular steel tubes connected by steel plates exhibited higher bearing capacity and ductility compared to those with separated rectangular steel tubes, and higher concrete strength resulted in higher bearing capacity but lower ductility. Considering the confinement mechanism of the steel section and stirrups to concrete, the concrete in the SRC columns was divided into three regions: unconfined concrete (UCC), partially confined concrete (PCC), and highly confined concrete (HCC). An analytical model was developed for predicting the axial load-displacement response of pentagonal section SRC columns based on the constitutive relationships for concrete in different regions. Furthermore, a finite-element (FE) model was developed and a parametric analysis was conducted using the verified FE model.

Progressive Failure Analysis of Composite/Aluminum Riveted Joints Subjected to Pull-Through Loading

Out-of-plane mechanical properties of the riveted joints restrict the performance of the wing box assembly of airplane. It is necessary to investigate the pull-through performance of the composite/metal riveted joints in order to guide the riveting design and ensure the safety of the wing box assembly. The progressive failure mechanism of composite/aluminum riveted joint subjected to pull-through loading was investigated by experiments and finite element method. A progressive damage model based on the Hashin-type criteria and zero-thickness cohesive zone method was developed by VUMAT subroutine, which was validated by both open-hole tensile test and three-point bending test. Predicted load-displacement response, failure modes and damage propagation were analysed and compared with the results of the pull-through tests. There are 4 obvious characteristic stages on the load-displacement curve of the pull-through test and that of the finite element model: first load take-up stage, damage stage, second load take-up stage and failure stage. Relative error of stiffness, first load peak and second load peak between finite element method and experiments were 8.1%, − 3.3% and 10.6%, respectively. It was found that the specimen was mainly broken by rivet-penetration fracture and delamination of plies of the composite laminate. And the material within the scope of the rivet head is more dangerous with more serious tensile damages than other regions, especially for 90° plies. This study proposes a numerical method for damage prediction and reveals the progressive failure mechanism of the hybrid material riveted joints subjected to the pull-through loading.

Experimental testing of platform-type and balloon-type cross-laminated timber (CLT) shear walls with supplemental energy dissipators

CLT technology is gaining notable popularity in both residential and non-residential applications throughout the world, providing a prospective solution to the height limitation of timber buildings. Recently, a growing number of studies have been focusing on energy dissipation strategies for CLT structures since the energy dissipation capacity of CLT structures might sometimes be challenged in seismic design. This paper presents an experimental investigation into the lateral performance of platform-type and balloon-type CLT shear walls with supplemental energy dissipators. Such supplemental energy dissipators are located between coupled CLT wall panels, intending to deform and dissipate energy through the rocking mechanism of CLT shear walls. Two kinds of energy dissipators were adopted, respectively, called O-shaped Flexural Plate (OFP) dissipator and Plate with Openings (PO) dissipator. Quasi-static tests were conducted on four one-third-scale two-story CLT shear wall specimens considering platform and balloon construction methods and these two types of supplemental energy dissipators. The experimental observations, load-displacement responses, energy dissipation capacities, stiffness degradation, and combined single-coupled wall behaviors of the specimens were obtained and compared. The test results showed that the OFP dissipator was quite efficient in dissipating energy, while the PO dissipator exhibited limited energy dissipation capability because it was prone to low cycle fatigue fracture. The supplemental energy dissipators dissipated more energy in balloon-type CLT shear walls compared to those in platform-type CLT shear walls due to the influence of construction methods on the demand of supplemental energy dissipators. In platform-type CLT shear walls, the coupled wall behavior of the walls in the second story was more evident than that of the walls in the first story.

In-plane and out-of-plane shear characteristics of reinforced mortarless concrete block masonry

Mortarless masonry systems can be reinforced and grouted to increase their in-plane and out-of-plane resistance for applications such as in the basement and retaining walls or load bearing walls in buildings. However, limited knowledge is available on the interface and out-of-plane shear strength and corresponding displacement characteristics of reinforced mortarless masonry walls. There are no proper design provisions available for designing mortarless masonry in the Australian Masonry Standards (AS3700). In order to comprehend the interface and out-of-plane shear behaviour of reinforced mortarless masonry, an experimental campaign was conducted in two stages. In the first stage, twelve reinforced mortarless triplets were constructed with two different types of interlocking blocks and reinforcement ratios (main vertical reinforcement perpendicular to bed joint interfaces) and tested under interface shear loading. In the second stage, twenty-four reinforced mortarless panels were built and tested under out-of-plane shear loading with the same types of interlocking blocks, reinforcement ratios and shear span ratios. The experimental results are provided in terms of failure patterns and load-displacement responses retrieved from the tested triplets and panels. The failure patterns of the triplets (under interface shear) and panels (under out-of-plane shear) are governed by the characteristics of dry joints between the blocks. The change in interlocking block types did not greatly influence the behaviour of reinforced mortarless masonry, however, change in the reinforcement and shear span ratios had significantly affected the load-displacement behaviour of triplets and panels. The experimental data established in this study was used to verify the applicability of existing design provisions for conventional reinforced masonry to the reinforced mortarless masonry. It was observed that the provisions outlined in Australian standard (AS3700) are most conservative in predicting the interface and out-of-plane shear strengths of reinforced mortarless masonry triplets and panels, in comparison to the provisions in Canadian (CSA S304-14) and American (TMS 402/602-16) standards.

LEGO-Inspired and Digitally-Fabricated steel reinforcement cage for Ultra-High performance concrete (UHPC) beams

Reinforced concrete is one of the most used structural configurations in the world, but the production of reinforcement cage is a labor-intensive, time-consuming and strenuous task. This study develops a new LEGO-inspired reinforcement cage system that is digitally fabricated through waterjet cutting, which can be assembled in three steps. The experimental program tests two ultra-high performance concrete (UHPC) beams reinforced by this LEGO-cage system, one with smooth surface and one with deformed ribs. Results show that including deformed ribs slightly increase the post-cracking stiffness of the beams while both beams exhibit a post-yielding plateau and a displacement ductility ratio over 8. An existing UHPC flexural model predicts the flexural strength (both yield and maximum strength) of the LEGO-cage-reinforced beams with errors below 4%. A two-dimensional finite element model, which is originally developed for rebar-reinforced UHPC, is found to well predict the load–displacement responses of LEGO-reinforced UHPC beams. A cost analysis reveals that adopting this new cage system can reduce the production cost and manual labor time by over 17% and 86%, respectively.

Experimental and numerical investigations of block shear failure in gusset plates welded to double angle members

Double angle braces are used extensively in structures to resist lateral loads such as wind, earthquake, and blast loads. A possible failure mode in the gusset plate when all-around weld is used for the angles is the block shear failure. To date, only limited test data on welded gusset plates failing in this mode have been reported in the literature, and all of them only considered concentrically loaded gusset plates. This paper investigates the block shear failure in welded gusset plates experimentally and numerically when connected to double angle members with possible in-plane load eccentricity effects. The test results, including failure loads, fracture sequences, and load-displacement responses are reported in detail. Results showed that tensile fracture was initiated adjacent to the angle heel weld and then propagated along the tension plane. Due to existing in-plane load eccentricity, shear planes did not rupture simultaneously and the shear plane adjacent to the heel weld failed earlier. Following the testing, a numerical investigation using nonlinear finite element analyses with ductile damage capability was performed on the tested specimens. Subsequently, a parametric study was carried out to generate further numerical data over a wide range of gusset and angle dimensions, welding configurations, and connection lengths. Accordingly, the existing design equations for block shear strength as given by AISC specification were evaluated. It was shown that AISC provides excessively conservative and scattered failure loads because of ignoring stress triaxiality and using shear yield instead of shear rupture in its strength equations. In addition, equations specified for welded gusset plates by previous studies were considered and shown to be unsafe for general use. To address these shortcomings, an improved block shear strength equation is proposed in this paper and shown to predict the gusset strength in block shear with improved accuracy.

Investigation of quasi-static indentation on sandwich structure with GFRP face sheets and PLA bio-inspired core: Numerical and experimental study

Composite materials incorporated in naval, aerospace, and automobile structures are exposed to unforeseen damages, which seriously damage their mechanical performance. In particular, the existence of hardly visual impairment on the in-service composite structures is a critical issue that highlights the severity of structural safety in an aircraft. The ability of these materials to sustain multiple impacts requires an understanding of the impact energy absorption to improve the material’s damage tolerance. The present study investigates the energy absorption, load response, failure modes, and damage mechanics under the quasi-static indentation of a sandwich structure. The structure comprises bio-inspired Poly-lactic Acid (PLA) core and Glass Fibre Reinforced Polymer (GFRP) laminates, used in real naval and aeronautical structures, under repeated low-velocity impact with reduced energies and quasi-static indentation. In addition, a lightweight sandwich structure’s damage performance is greatly influenced by its core geometry. Therefore, choosing an appropriate core structure is critical. A Numerical model is developed for the composite structure under quasi-static indentation loads, considering suitable material properties and damage models for the core and face sheets. These results are then compared with the experimental investigation. The load–displacement response and the energy absorption characteristics of the sandwich structure showed good agreement for the experimental and numerical analysis results.

Guided identification of nonlinear reduced-order models via the incorporation of von Kármán beam theory

A reduction in the number of Degrees Of Freedom (DOFs) of a nonlinear structural model can significantly decrease the computational time of dynamic analyses, especially in problems where long analyses are required. A Reduced-Order Model (ROM) of a structural system is commonly generated using some combination of dimensionality reduction, such as substitution of a modal basis or static condensation of membrane DOFs. Perhaps the most common and widespread framework for developing low-order models of continuous systems is the Ritz method in conjunction with a smooth modal basis. The Ritz method requires access to the closed form governing differential equations, and it is difficult to implement for problems with complex boundary conditions. In recent decades, an alternative framework that instead constructs a low-order model from an existing Finite Element Model (FEM) has been developed. Such models are typically known as NonLinear Reduced-Order Models (NLROMs). Such NLROMs can be used to handle complex boundary conditions so long as the FEM can do the same, and they allow the analyst to start from an existing finite element package as opposed to directly working with the governing differential equations. The form of the NLROM restoring force function is assumed by the analyst prior to identifying the model, and the parameters of the function are identified to achieve a high-quality fit to the FEM load–displacement data. This research aims to examine the connection between classically derived models using the Ritz method and NLROMs in order to predict the coefficients of NLROMs and to develop simplifying assumptions about their structure. Specifically, the Condensed Von Kármán (CVK) beam equation is used as a basis for the study of nonlinear beam structures. The Ritz method is applied to the CVK beam equation, and the matrix form of the equilibrium equation is determined. The equivalence between the CVK coefficients and the NLROM coefficients is shown, and a simplified, tangent stiffness-based identification procedure is proposed to determine the coefficients of the CVK-based model. An arc-length continuation algorithm is used to predict the static load–displacement response of the models studied and to assess the accuracy of the ROMs. In the case of initially straight, post-buckled beams, the proposed identification procedure is shown to generate a model that generally outperforms a corresponding NLROM identified using a more traditional displacement-based procedure.

An In-Situ Low Temperature-Mechanical Coupling Test System for Battery Materials

The mechanical properties of battery materials under actual service conditions are crucial for the safety and durability of batteries, but specialized systems which are able to carry out in-situ low temperature-mechanical coupling testing of battery materials are lacking. In the present work, a low temperature-mechanical coupling test system for battery materials is developed to investigate the mechanical properties of battery materials under low-temperature conditions. A semi-enclosed stable low-temperature loading unit is built by using high-power Peltier coolers and a double circulating water cooling system, which facilitates the observation of the changes in morphology and temperature of battery materials at different low temperatures. Based on the proposed double circulating water cooling system, a target temperature of -40 °C with maximum fluctuation lower than ±0.40 °C was realized within a rapid refrigeration time of 112 seconds. Through in-situ tensile tests of typical lithium-ion battery separators at temperatures in a range from -40 °C to 20 °C, the load-displacement response and the brittleness trend of the separators with the decrease of temperature are confirmed, which verify the low-temperature loading capacity and testing function of the proposed system. Compared with the separators at 20 °C, the strain to fracture and fracture energy under -40 °C decreased by 29.3% and 15.2%, respectively.

Structural behavior of axially loaded high strength concrete columns reinforced longitudinally with glass fiber reinforced polymer bars

This study investigated the behaviour of axially loaded high strength concrete columns reinforced longitudinally with glass fibre reinforced polymer bars. Total six Reinforced Concrete (RC) columns and six Glass Fibre Reinforced Polymer (GFRP) reinforced concrete columns made with High Strength Concrete (HSC) with the addition of 1.20% of Alkali Resistant Glass Fibre (ARGF). The columns were cast with 1000 mm height and cross-sectional area is 150 mm x 150 mm and were tested under axial loading. The main objective of this study including to increase axial load carrying capacity and stiffness and reduce the ductility, mode of failure, and axial load-displacement response of columns. The RC columns are compared to the GFRP RC columns, and the GFRP RC columns are only carried 90% of the axial load compared to the RC columns. The Finite Element Model (FEM) was used to analyses all columns, and FEM helps predict the axial load.

Finite Element Analysis of Crack Propagation in Adhesive Joints with Notched Adherends

The adherends notching technique has been the subject of a few recent studies and consists of tailoring the geometry of the adjoined layers to mitigate the bondline peak stresses and enhance the joint strength. In the present study, we explored the effect of the adherends notching technique on crack propagation using finite element (FE) simulations based on the cohesive zone model (CZM) of fracture. Double cantilever beam (DCB) adhesive joints subjected to quasistatic loading were considered as a model material system. An array of equally spaced notches was placed on the faying sides of the adherends, oriented perpendicularly to the direction of crack growth. A parametric investigation was carried out to ascertain the role of the notches and the input cohesive properties on various performance metrics, e.g., load-displacement response and dissipated energy. The proposed notching strategy promotes an unstable crack pinning/depinning process, which effectively delays crack growth and increases the effective work of fracture. Additionally, we found that the overall behaviour is tunable by changing geometric (i.e., notch spacing and depth) and bondline material properties.

Shear strengthening performance of GFRP reinforced lightweight SCC beams: Experimental and analytical study

Light weight construction using Glass Fibre-Reinforced Polymer (GFRP) bars and structural light weight concrete (LWC) have increased recently and offers a wide spectrum of advantages over traditional normal weight concrete (NWC) structures. However, the shear strengthening and rehabilitation performance of LWC beams reinforced with GFRP bars is very limited and currently there are no guidelines related to it. Therefore, this study presents the results of an experimental investigation on the shear strengthening behaviour of lightweight self-consolidating concrete (LWSCC) beams reinforced with GFRP bars. The test parameters studied in the experimental program were the longitudinal reinforcement ratio and strip configuration or orientation. A total of twelve shear deficient GFRP reinforced beams were prepared with a shear span to depth ratio of 3.12 and subjected to static four-point bending. Five beams in each series were externally strengthened with different configurations of Carbon Fibre-Reinforced Polymer (CFRP) strips and one beam served as a control specimen to compare the performance of the strengthened specimens. Crack patterns, load–displacement response curves, and strain in the external CFRP strips were recorded until the failure ultimate load. The results of the experimental study indicated that the external CFRP strips improved the nominal shear capacity of GFRP reinforced LWSCC beams, and the contribution of external CFRP strips was sensitive to the reinforcement ratio. The nominal shear capacity of the strengthened specimens increased from 33.3 to 168% compared to the control specimen. U-wraps with horizontal strips in the compression and tension zone were the most effective configuration, showing the highest increase in shear strength compared to other strengthened specimens. Moreover, the shear capacity was theoretically predicted using different Fiber-Reinforced Polymer (FRP) design standards and guidelines which were compared with the experimental results. All the FRP design standards have overestimated the shear capacity of LWSCC beams, and a modified equation with a set of recommendations was proposed based on the experimental study. In addition, a reduction factor of 0.75 is recommended for conservative design.

Failure characteristics of reinforced concrete circular slabs subsequently subjected to fire exposure and static load: An experimental study

AbstractThis study investigated the effect of fire on the ultimate load‐bearing capacity of reinforced concrete (RC) slabs. The structural response of RC circular specimens subjected to static load conditions after exposure to a hydrocarbon fire on one side of the specimen was examined. Two fire exposure times were considered (60 and 120 min) in addition to reference non‐exposed specimens. The static response was evaluated in the damaged specimens in residual conditions after natural cooling from the elevated temperatures. The temperature distribution across the thickness of the slabs and their load–displacement response was measured. The decrease in the stiffness of the slabs due to the thermal exposure was studied by means of direct ultrasonic pulse velocity (UPV) measurements made before and after the fire tests. The decrease in global stiffness was partially accounted for by UPV measurements. The experimental results showed two peaks in the load‐deflection response of the slabs. The first peak was related to an arching mechanism introduced by the specific set‐up used. The second peak, corresponding to the ultimate load, occurred due to tensile membrane action at large deflections. While the former was strongly affected by the fire exposure, with the load being halved after the 120‐min exposure, the latter was not greatly affected by either the presence of fire or the exposure time. Simplified mechanical models were used to explain the behavior of the RC slabs during the tests.

Axial mechanical behavior of innovative inter-module connection for modular steel constructions

Modular steel construction (MSC) is a construction mode where volumetric modules are prefabricated in a factory and assembled on-site to form permanent buildings. Inter-module connections are critical to the integrity and robustness of modular steel constructions (MSCs). In this paper, the mechanical behavior of a typical corner inter-module connection under axial tensile and compressive loads was investigated. A tensile test of the inter-module connection was carried out to investigate their axial tensile behavior. The refined numerical model was established, calibrated against the test results and then used to simulate the axial tensile and compressive mechanical behaviors of the inter-module connection. The effects of key design parameters on the axial load-displacement responses of the connection, including the bolt gasket thickness, the bolt diameter and the preload were investigated. The inter-module connection was shown to exhibit excellent load-carrying capacity under axial compression and adequate performance under tension. In terms of tensile resistances, the bolt gasket thickness and the bolt diameter were shown to be the critical parameters, while the section size of the modular columns dominated the compressive load-carrying capacity. Through geometrical parameters correlation analysis, a simplified piecewise polynomial axial load-displacement model with different stiffnesses in tension and compression was employed for predicting the axial load-displacement relationship. The proposed model was shown to be capable of accurately capturing the axial resistance characteristics of the connection while maintaining simplicity, and is therefore recommended for use to represent the axial behavior of the inter-module connection in global frame modelling.

Numerical simulations of displacement piles in a tropical soil

The behavior of pile foundations under axial loading is directly influenced by the effects that its installation process induces in the surrounding soil. Consequently, the consideration of these effects is essential for the correct numerical modeling of these geotechnical structures. In the present study, numerical simulations of driven cast-in-situ piles under axial loading have been carried out using finite element analysis. Three 3.5 m long piles with diameters ranging from 114.3 to 219.1 mm were analyzed. The pile installation effects have been considered indirectly by employing two distinct approaches, both based on the concepts of cylindrical cavity expansion. The behavior of the tropical soil profile is described with the Hardening Soil constitutive model. The load-displacement response and load distribution along the pile obtained with the numerical simulations have been analyzed and compared with in-situ load tests results. In the failure conditions, both approaches accurately predicted the bearing capacity of the piles, with an average error of only 2% compared to the measured values. The results in terms of load distribution over depth were also satisfactory. The difference between measured and numerical ultimate base resistance values ranged from 0% to 30%. The good agreement between the numerical and experimental results indicates that the proposed numerical approaches have been effective in simulating the piles installation process and reinforces the importance of considering the installation effects in the numerical modeling of these geotechnical structures. Both approaches can also be used to predict the bearing capacity of displacement piles.

Effect of Using ECC Layer on the Flexural Performance of RC Beams Previously Strengthened with EB CFRP Laminates

This paper studies the efficiency of applying an engineered cementitious composite (ECC) layer to the tensile surface of (RC) beams that were previously strengthened using externally bonded (EB) carbon fiber-reinforced polymer (CFRP) laminates. One control and ten strengthened RC beams were produced and tested utilizing a four-point loading regime. For strengthened beams, two beams were kept strengthened using only CFRP, and additional ECC layers were added to the rest of the strengthened beams. The CFRP width and overlap length and position were among the test factors. Experimental results revealed that strengthening RC beams with CFRP laminates enhanced both the stiffness and flexural capacity of beams. Additional enhancements were obtained through the application of the additional ECC layers. The existence of the ECC layer alongside the CFRP laminate improved the flexural capacity by 102% and 125% when using CFRP widths of 50 mm and 100 mm, respectively, and the stiffness was improved by an average value of 318%. Three-dimensional (3D) finite element models (FEMs) were developed using ABAQUS software and verified against the experimental results to model the response of the tested beams. The verified model was used to conduct a parametric study to consider the effect of the ECC layer thickness and the reinforcement ratio on the strengthened beam behavior. The numerical results revealed that the effect of the reinforcement ratio was more significant than the ECC layer thickness in enhancing the load-displacement response, especially after the cracking stage.