Fiber-reinforced Polymer Jackets Research Articles

Structural behavior of RC one-way slabs strengthened with ferrocement and FRP composites

Existing research lacks focus on the structural behavior of reinforced concrete (RC) one-way slabs reinforced with ferrocement, and there's a notable absence of comparative studies between fiber-reinforced polymers (FRPs) and ferrocement strengthening methods for these slabs. Given the cost-effectiveness and widespread use of ferrocement in structural reinforcement, this study aimed to address these gaps through an experimental program. Three sizes of wire mesh, categorized as Type-I (small), Type-II (medium), and Type-III (large), were employed in this study. Chemical or mechanical anchors were used to attach ferrocement jackets. Moreover, 6, 12, or 18 anchors were used to assess the effect of anchor configuration. The goal was to enhance the structural performance of slabs and compare them with slabs reinforced using FRP jackets. The study focused on preventing debonding of the strengthening layers, employing either mechanical or chemical anchors. All slabs exhibited ductile failure with flexural cracks. The peak load and ultimate deflection were enhanced by up to 49.00% and 109.07%, respectively, by the application of ferrocement jackets, whereas the dissipated energy was increased by up to 174.00 %. Notably, the use of chemical anchors demonstrated a superior ability to delay debonding and enhance ductility compared to mechanical anchors. Slabs reinforced with glass FRP (GFRP) showed delayed debonding relative to carbon FRP (CFRP) reinforced slabs, indicating the superior performance of chemical anchors with GFRP layers. Moreover, the type and size of wire mesh significantly influenced performance, with small and medium-sized mesh configurations enhancing ductility, while large-sized mesh exhibited relatively earlier debonding. The orientation of the wire mesh also played a crucial role, with parallel orientation to the longitudinal axis of slabs yielding better performance.

Failure patterns and mechanical behavior of the cement mortar column partially confined by the FRP jacket

Fiber-reinforced polymer (FRP) composite has been recently adopted to maintain the integrity of infrastructure made of cement mortar, attributed to its high strength-to-weight ratio and easy-to-construct. To obtain an in-depth understanding about the compressive behavior of cement mortar samples with variable FRP center wrapping heights, both the acoustic emission (AE) response and deformation characteristics of which were comprehensively investigated in the present research. The relationship between the confinement provided the exterior FRP jacket and the mechanical characteristic was also explored, followed by the economic analysis on this reinforced technique. Test results indicated that both the deformation ability and the load-bearing capacity gradually increased with the increased center wrapping height of the FRP jacket. When the larger the AE energy generated at the initial compression stage, the more dispersed AE localization. Meanwhile, these main cracks occurred on the surface of reinforced cement mortar generally transformed from the FRP wrapping strip towards other extremities. Correspondingly, the number of tensile cracks of FRP partially wrapped cement mortar decreased with the increased axial deformation. Note that the residual integrity of these reinforced cement mortar with larger FRP-center wrapping height is much superior than its counterparts. The force state of partially reinforced cement mortar with FRP confinement was also discussed in the present research and the results of which were compared with existing theoretical models. Compared to other theoretical models, Teng's model shows the most accuracy in predicting the mechanical behavior of FRP partially reinforced cement mortar.

Stress-strain models for FRP-confined thermally damaged concrete

Fiber-reinforced polymer (FRP) jackets have been increasingly used for the strengthening and confinement of concrete columns. Despite extensive research efforts yielding various concrete confinement models that can be broadly classified as design- and analysis-oriented, an accurate model is lacking for the design of FRP-strengthened thermally damaged concrete columns. This paper presents a comprehensive review of existing experimental studies on FRP-confined thermally damaged concrete columns and collects a large database of the corresponding test results. Then, a theoretical analysis is conducted to evaluate the accuracy and reliability of typical concrete confinement models (originally proposed for undamaged concrete) through extensive comparisons with the corresponding test data. The analytical findings have revealed that none of the existing models can accurately predict the compressive behavior of FRP-confined thermally damaged concrete. Two novel confinement models, design-oriented and analysis-oriented, are proposed for FRP-confined thermally damaged concrete. These novel models have appropriately considered the effects of high-temperature exposure on the confining pressure of FRP jackets and the lateral deformation characteristics of thermally damaged concrete. The proposed models are then validated by comparing the model predictions with the corresponding test results, indicating that these models can accurately predict the compressive stress-strain responses and dilation behavior of FRP-confined thermally damaged concrete.

FRP spiral strip-confined concrete columns: Stress-strain behavior and size effect

It is well-known that the hoop rupture strain of fiber-reinforced polymer (FRP) jacket in an FRP-confined concrete column is commonly much lower than that obtained from coupon tests. To improve the strain efficiency of the FRP jacket, FRP spiral strip wrapping scheme has been proposed. In the present study, totally 24 circular column specimens [including 16 FRP spiral strip-confined concrete (FSSCC) column specimens] of four different sizes, with a diameter ranging from 100 mm to 400 mm, were tested under uniaxial compression. The particle image velocimetry (PIV) technique was adopted to obtain the hoop and axial strains as well as the strain distributions of the test specimens. The test results showed that the FRP hoop rupture strains measured by the PIV technique in the FSSCC columns are close to that from the coupon tests. The size effect in terms of compressive strength and stress-strain behavior is obvious in the test FSSCC columns. An existing stress-strain model for FRP-confined concrete was then modified to predict the test results. Finally, a field application of the FRP spiral strip wrapping technique completed recently was also briefly introduced.

Cyclic axial compressive performance of hybrid double-skin tubular square columns

This paper presents an experimental study on the cyclic axial compressive behavior of FRP-concrete-steel hybrid double-skin tubular columns. The square column specimens were cast with an external Fiber Reinforced Polymer jackets, inner steel tube and concrete in between. The height of the columns was 500 mm and the side dimension was 150 mm. The effects of loading scheme, void ratio and diameter-thickness ratio on axial compression behavior were investigated. A total of eight columns were tested under monotonic and cyclic axial compression. The experimental results show that the effect of loading scheme on axial stress-strain envelope curve and the peak load were not significant, and the ultimate state of the square columns subjected to cyclic axial compression was very similar to that of specimens subjected to monotonic axial compression. Besides, compared with void ratio, the diameter-thickness ratio of the inner steel tube has significant influence on the peak load of the columns when subjected to cyclic axial compression.

Behavior of FRP grid-reinforced ultra-high performance concrete (UHPC) pipes under lateral compression

In this paper, ultra-high performance concrete (UHPC) pipes internally reinforced with fiber-reinforced polymer (FRP) grid (abbreviated as “FRP grid-UHPC pipe”) are proposed. The lateral load carrying performance of FRP grid-UHPC pipes was explored by testing 15 pipe specimens. The test variables included the presence and amount of FRP grid reinforcements, pipe thickness, as well as the presence of carbon FRP (CFRP) jacketing. Results showed that separation failure and flexural fracture were the primary failure modes for the pipes with and without FRP grid reinforcements, respectively. The typical load-vertical displacement curve of a FRP grid-UHPC pipe exhibited a two-stage ascending behavior. Without CFRP jacketing, the two ascending segments were linked by a load reduction, while the transition was smooth with CFRP jacketing. For the variables, it is found that the presence of FRP grid reinforcements could enhance the pipe initial cracking load by approximately 30%, while increasing the FRP grid layers could lead to a much steeper rising in the second ascending segment. Increasing pipe thickness and applying CFRP jacketing could increase the slopes of both initial and second ascending segments. Therefore, increasing pipe thickness (from 30 mm to 45 mm) and applying 1-ply CFRP jacketing could enhance the pipe ring stiffness by 422% and 115% respectively, which was more efficient that increasing the FRP grid layers.

Analytical model to predict axial stress-strain behavior of heat-damaged unreinforced concrete columns wrapped by FRP jacket

Although there are several confinement models to obtain analytically the axial stress-strain response (fc-εc) of concrete columns wrapped with fiber-reinforced-polymer (FRP) jacket at ambient conditions, a reliable design-oriented model to determine the fc-εc of heat-damaged concrete columns post-confined with FRP is still lacking in the literature. This study aims to address this research gap, by proposing a formulation that predicts the favourable effects of FRP confinement on concrete elements previously exposed to high temperatures. This model proposes a closed-form formulation to derive a fc-εc expression, including a set of strength and strain sub-models to calculate the stress/strain information at transition and ultimate points defining the stress-strain response. To develop the model and calibrate its key components by data analysis of statistical treatment techniques, a large test database of FRP confined unheated/heat-damaged concrete of circular/square cross-section consisting of 1914 specimens was collected. The proposed design-oriented model is able to demonstrate the influence of pre-existing thermal damage on the axial fc-εc relationship, whose reliability is revealed comprehensively through predicting data from several experimental heat-damaged concrete specimens confined with FRP systems.

Compressive behaviour of lump-grout material under lateral confinement: Laboratory tests

The lump-grout (LG) material consisted of coarse lumps and pumpable grout has been developed as an alternative infill material to cementitious grout (CG) material in secondary standing support for underground mines. This paper aims to further explore the compressive behaviour of the LG material under variable lateral confinements. A total of 30 LG specimens and 15 CG specimens, either under the active confinement via a Hoek cell or the passive confinement with a fibre-reinforced polymer (FRP) jacket, were prepared and tested. The main test variables included the confining pressure (i.e., 0, 2, 4, 6, 8, 12, 16 MPa) applied by a Hoek cell and the FRP jackets made of variable FRP composites (i.e., CFRP, GFRP and UHMWPE FRP). Test results demonstrated that both the compressive strength and the axial deformation of the LG material were obviously enhanced attributed to effective lateral confinement. The stress path independence assumption was also verified from this research, which provided a feasible access to build the relationship between the active- and passive confinement to the LG material. The in-depth comparison with the CG material, the LG material is much suitable as the infill material for the standing support, in terms of its cost-effectiveness and environmentally friendly.

Evaluation of Hybrid Fiber Multiscale Polymer Composites for Structural Confinement under Cyclic Axial Compressive Loading

Fiber reinforced polymer (FRP) confinement is recognized as the most promising technique for the strengthening and retrofitting of concrete structures. In order to enhance the performance of conventional epoxy-based FRP composites, nano filler modification of the epoxy matrix was implemented in the current study. In particular, the cyclic loading response of standard concrete specimens externally confined by epoxy-based natural and hybrid fiber reinforced polymer systems was investigated. The confinements were realized with sisal fiber reinforced polymer (SFRP) and hybrid sisal basalt fiber reinforced polymer (HSBFRP). Moreover, the effects of multiwalled carbon nanotubes (MWCNT) were also investigated. Three different specimen sets were considered for study: (i) unconfined specimens, (ii) epoxy-based FRP confined specimens and (iii) MWCNT incorporated epoxy-based FRP confined specimens. The specimens were tested in repeated compressive mode in loading-unloading cycles at increasing displacement levels. The test results revealed that FRP wrapping could enhance the mechanical behavior of unconfined columns in terms of strength and ductility. Moreover, it was evident that the mechanical properties of the epoxy matrix were enhanced by MWCNT incorporation. The developed epoxy-based FRP confinement containing MWCNT ensures improvement in axial strength by 71% when compared with unconfined specimens. The epoxy-based FRP confinement, with and without MWCNT, exhibited a high strain redistribution behavior around the concrete core. In comparison to the unconfined specimens, the confinement could increase the sustained axial strain from 0.6 to 1.4% using epoxy-based FRP confinement and to 1.6% with MWCNT incorporated epoxy-based FRP confinement. Further, an empirical model was developed to predict the ultimate axial stress of concrete columns confined externally with FRP jackets. The ultimate compressive strength obtained from the experimental study was compared with the proposed model, and the observed deviation was lower than 1%.

Reliable machine learning for the shear strength of beams strengthened using externally bonded FRP jackets

All over the world, shear strengthening of reinforced concrete elements using external fiber-reinforced polymer jackets could be used to improve building sustainability. However, reports issued by the American Concrete Institute called for heavy scrutiny before actual field implementation. The very limited number of proposed shear equations lacks reliability and accuracy. Thus, further investigation in this area is needed. In addition, machine-learning techniques are being implemented successfully to develop strength models for complex problems including shear, flexure, and torsion. This study aims to provide a reliable machine-learning model for reinforced concrete beams strengthened in shear using externally reinforced fiber polymer sheets. The proposed model was developed and validated against the experimental database and the very limited models in existing literature. The model showed better agreement with the experimentally measured strength compared to the previous models, which accounted for the effect of various parameters including but not limited to: the element geometry, strengthening details, and configurations. The model could guide the further developments of design codes and mechanical models.

Experimental and Numerical Study on Seismic Performance of PEN FRP-Jacketed Circular RC Columns

This paper presents an experimental study on the seismic behavior of polyethylene naphthalate (PEN) fiber–reinforced polymer (FRP)-jacketed circular reinforced-concrete (RC) columns. A total of seven specimens were tested under constant axial load and cyclic lateral load. The key parameters studied were the thickness (one, two, and three layers) and type (PEN FRP and CFRP) of FRP jacket. Test results indicated that the control column failed by buckling of the longitudinal reinforcement and shortage of ductility, while concrete spalling and bar buckling were effectively inhibited by the application of external FRP jacket. It is also observed that PEN FRP-jacketed specimens had more additional strain capacity compared with CFRP-jacketed specimens at the final condition. The additional strain capacity can serve as a safety reserve for structures and make PEN FRP more suitable for strengthening large or noncircular columns. Furthermore, it is found that 1-ply PEN FRP and 1-ply CFRP had a similar strengthening effect and thus the design of PEN FRP-strengthened column can simply refer to the design method of CFRP-strengthened columns in current codes. Different FRP thickness and types had marginal impact on the hysteretic curves of the specimens, which was attributed to the low axial load ratio (0.15) and high slenderness ratio (5.25) adopted in this paper. Finally, based on a cyclic stress–strain model for longitudinal reinforcement, including buckling effect, developed by the authors in a previous study, the test columns were simulated by the Open System for Earthquake Engineering Simulation (OpenSee)s to achieve an in-depth understanding of the experimental findings and associated strengthening mechanisms. Further parametric analyses showed that considering bar buckling played a significant role in accurately predicting the hysteretic response of FRP-jacketed columns.

Compressive behavior of FRP-confined ultra-high performance concrete (UHPC) and ultra-high performance fiber reinforced concrete (UHPFRC)

Due to its superior mechanical properties and durability, ultra-high performance concrete (UHPC) or ultra-high performance fiber reinforced concrete (UHPFRC) has emerged as a promising alternative to conventional materials in both strengthening of deficient structures and building of new structures. Contrast to the ductile tensile behavior of UHPFRC, the compressive behavior of both UHPC and UHPFRC is much more brittle. To tackle such demerit, the use of fiber-reinforced polymer (FRP) to provide confinement is an efficient method. This study aims to investigate the stress–strain behavior of FRP-confined UHPC/UHPFRC through axial compression tests of 40 FRP-confined UHPC/UHPFRC cylinders, with the confinement mechanism being carefully analyzed and explained. The test variables included the type and thickness of FRP jacket, the compressive strength of UHPC/UHPFRC, the volume fraction of steel fibers, and the specimen size. The test results showed that FRP-confined UHPC/UHPFRC exhibited a large deformation capacity and generally a bilinear axial stress–strain curve. Axial stress reductions or fluctuations occurred after the first ascending branch for the UHPC specimens; however, such axial stress reductions or fluctuations became less obvious after steel fibers were added. Finally, existing models for the ultimate condition of FRP-confined UHPC/UHPFRC were evaluated using the test results in the present study.

Tensile behavior and durability prediction of GFRP-steel composite bars under chloride environments

A fiber-reinforced polymer (FRP)-steel composite bars (FSCBs), with an inner steel core and outer FRP jacket, is a novel type of reinforcement designed to inherit good durability and ductility suitable for seawater sea sand concrete structures. The long-term tensile behavior of FSCBs in chloride environments is important. The long-term tensile behavior of glass-type FSCBs with different fiber layer thicknesses under chloride environment attack was investigated in this study. FSCBs with an inner steel bar of fixed diameter (8 mm) and an outer FRP jacket of three thicknesses (2, 4, and 6 mm) were used for research. Seawater-immersion accelerated-aging experiments at three different aging temperatures (23, 40, and 60 °C) and aging times (1, 6 and 12 months) were conducted. The failure modes, equivalent elastic modulus, pseudo strain hardening moduSTlus, and tensile strength retention of the FSCBs under the above mentioned aging temperatures and times were analyzed. The experimental results determined that the chloride environment had no significant effect on the equivalent elastic modulus of the FSCBs. However, the pseudo-strain hardening modulus of the FSCBs decreased with increasing aging time. Moreover, the tensile strength retention of the FSCBs decreased with increasing temperature under the same aging time and FSCBs diameter. A prediction model for the tensile strength retention of FSCBs with different FRP layer thicknesses at different aging temperatures and times was proposed and validated. The results provided a better understanding of the durability of FSCBs in marine hydrothermal environments to establish the criteria and standards of design.

Strengthening RC square columns with UHP-ECC section curvilinearization and FRP confinement: Concept and axial compression tests

In this paper, a novel column strengthening technique incorporating section curvilinearization (SC) using ultra-high performance engineered cementitious composites (UHP-ECC) and fiber-reinforced polymer (FRP) confinement is proposed and validated. Eleven large-scaled FRP-confined square reinforced concrete (RC) columns with SC using UHP-ECC as the additive material were prepared and tested. The main parameters investigated in this paper included the FRP thickness, the rise-to-span ratio, and the strength of the additive concrete. Test results show that the SC technique with FRP jacketing and UHP-ECC as the additive material enhances the load-bearing capacity of the RC columns by 52% with a 17% section increment. By assessing the existing design-oriented stress–strain models of confined concrete in curvilinearized square columns (CSCs) using the test results obtained in this study, it reveals that the current models could underestimate the ultimate strength of the confined concrete in CSCs with a two-layer FRP wrap, and therefore further research on the improvement on the stress–strain model of confined concrete in CSCs becomes necessary.

Finite-Element Analysis of Wall-Like RC Columns Strengthened with FRP and TRM Jackets under Concentric and Eccentric Loadings

The present paper shows the results of nonlinear finite-element analysis (FEA) of fiber-reinforced polymer (FRP) and textile-reinforced mortar (TRM) confined reinforced concrete (RC) wall-like columns under concentric and eccentric axial loads. The FEA column models were validated with an experimental study in the literature. A parametric study was performed on the validated models to examine the effectiveness of FRP versus TRM considering various columns’ cross section aspect ratios, number of layers, and eccentricities. In addition, interaction diagrams were constructed for the control and strengthened columns. Good agreement was achieved between the experimental and validated FEA results. The parametric study results showed that, as compared to TRM, FRP jackets were more effective in terms of axial strength improvement. This effectiveness was less pronounced in columns with higher aspect ratios. Furthermore, the effectiveness of both systems was distinct when three layers were applied with 45% and 39% enhancements in the axial strength as compared to the control model, respectively. Furthermore, the axial strength of all columns reduced with higher eccentricity values. As the eccentricity increased, the axial capacity of the models strengthened with FRP converged with the control ones. In general, the TRM-confined model’s interaction diagram was superior to that of its FRP-confined counterparts.

Fiber-Reinforced Polymer Confined Concrete: Data-Driven Predictions of Compressive Strength Utilizing Machine Learning Techniques

Accurate estimation of the mechanical properties of concrete is important for the development of new materials to lead construction applications. Experimental research, aided by empirical and statistical models, has been commonly employed to establish a connection between concrete properties and the resulting compressive strength. However, these methods can be labor-intensive to develop and may not always produce accurate results when the relationships between concrete properties, mixture composition, and curing conditions are complex. In this paper, an experimental dataset based on uniaxial compression experiments conducted on concrete specimens, confined using fiber-reinforced polymer jackets, is incorporated to predict the compressive strength of confined specimens. Experimental measurements are bound to the mechanical and physical properties of the material and fed into a machine learning platform. Novel data science techniques are exploited at first to prepare the experimental dataset before entering the machine learning procedure. Twelve machine learning algorithms are employed to predict the compressive strength, with tree-based methods yielding the highest accuracy scores, achieving coefficients of determination close to unity. Eventually, it is shown that, by carefully manipulating experimental datasets and selecting the appropriate algorithm, a fast and accurate computational platform is created, which can be generalized to bypass expensive, time-consuming, and susceptible-to-errors experiments, and serve as a solution to practical problems in science and engineering.

Retrofitting of Shear Compression Failure-Critic Short Columns with a New Technique

One of the reasons that cause the collapse of buildings is deficient short columns, which need to be retrofitted to prevent the collapse of the building in a potential earthquake. External reinforced concrete (RC), steel plates, and fiber-reinforced polymer (FRP) jacketing are standard retrofitting methods to retrofit columns to increase their shear capacity. However, in compression shear failure, the effectiveness of steel and FRP jacketing is quite limited due to the premature buckling of the FRP and steel material. On the other hand, RC jacketing is not practical because it requires more labor and covers more architectural places. Thus, the main motivation of this study is to present the effectiveness of a new method to retrofit short columns, including those with dominated shear compression failure. For this purpose, HSPRCC (high-performance steel plate-reinforced cementitious composite) was adapted to retrofit such short columns. This method is a combination of high-performance concrete and perforated steel plates. Short-column specimens representing existing RC buildings were retrofitted using the HSPRCC and tested. Perforated steel plates anchored to the specimen by steel bolts and repair mortar are used as a matrix. The retrofitted specimens were found to exhibit much better performance both in terms of shear strength and deformation capacity. It was also observed that the retrofitting method is effective in contributing to increasing the compression shear capacity.

Performance of Steel Bar Lap Splices at the Base of Seismic Resistant Reinforced Concrete Columns Retrofitted with FRPs—3D Finite Element Analysis

This paper examines analytically the design criteria for the composite retrofit of reinforced concrete (RC) columns with a short lap splice length of steel rebars inside the critical region. The advanced potential of pseudo-dynamic three-dimensional (3D) finite element (FE) modelling is utilized to investigate critical design parameters for the required carbon fiber-reinforced polymer (FRP) jacketing of RC columns with a rectangular cross-section based on the experimental lateral force-to-drift envelope behavior of characteristic cases from the international literature. The satisfactory analytical reproduction of the experimental results allows for the systematic numerical investigation of the developed stress along the lap splice length. The maximum lateral force and the horizontal displacement ductility of the column, as well as the maximum developed tensile axial force on the longitudinal bars, their variation along the lap, the bar yielding, and the plastic hinge length variation, are considered to determine the seismic behavior of the columns. For the first time, cases of smooth bar slip together with delayed bar yielding or without bar yielding are identified that may be recorded through a “ductile” P-d seismic response. Such pseudo-ductile response cases are revisited through suitably revised redesign criteria for adequate FRP jacketing.

A comparative study on the seismic performance of RC beam-column joints retrofitted by ECC, FRP, and concrete jacketing methods

Reinforced concrete (RC) beam-column joints in many old buildings do not have appropriate seismic detailing that allows them to provide sufficient strength and stiffness in strong seismic events. To improve the seismic performance of these deficient beam-column joints, this study proposes a new retrofitting method based on high-strength steel bar mesh and Engineering Cementitious Composite (ECC), a fiber-reinforced cementitious material that shows high tensile ductility and damage tolerance. The proposed method reduces the required size of the retrofitting jacket through the combined use of ECC jackets and high-strength steel bar mesh. The performance of the proposed ECC jacketing method was compared with that of concrete jackets and fiber-reinforced-polymer (FRP) jackets. Experimental program included cyclic testing of four exterior beam-column joints, i.e., one control specimen and three others retrofitted using ECC, concrete, and FRP jacketing. Results showed that (1) reinforced ECC jackets confined the joint core and prevented localized damage in the joint zone via formation of dense and fine cracks, (2) the beam-column joint retrofitted using ECC jackets with high-strength steel mesh exhibited the favorable beam flexural failure, while the other three joints showed joint shear failure, (3) compared to other two retrofitting methods, the reinforced ECC jacket more effectively increased the strength, stiffness retention, energy dissipation capacity, deformation capacity, and collapse drift. In addition to experimental study, suitable strength models were suggested to evaluate the strength and failure patterns of the retrofitted exterior beam-column joints.

Flexural Behavior of Insulated Concrete Sandwich Panels using FRP-Jacketed Steel-Composite Connectors

This study presented the experimental and theoretical results of insulated concrete Sandwich panels with innovative dumbbell-shaped steel fiber-reinforced polymer (FRP) composite bar (SFCB) connectors under flexural load. The influences of FRP thickness and raised thickness of dumbbell ends of connectors, axial compression ratio, the content of vitrified microspheres in the wythes, and loading direction were discussed. The increase in thickness of a glass FRP (GFRP) jacket on the hybrid bar from 2 to 3 mm led to increased initial cracking load, ultimate load, and flexural stiffness of the Sandwich panels by 75, 49, and 16%, respectively. The increase in the thickness of dumbbell ends from 4 to 6 mm led to increased initial cracking load, ultimate load, and flexural stiffness of the Sandwich panels of 18, 46, and 9%, respectively. The incorporation of vitrified microspheres in concrete wythes resulted in a significant increase in the load-carrying capacity of Sandwich panels but decreased ductility. Increased axial compression ratio from 0/1 to 0.2/1 contributed in improving the crack resistance and ultimate loads of Sandwich panels. Further increase of the axial compression ratio to 0.4/1 led to crushing failure of concrete wythe ends. Specimens under negative loads had higher ultimate loads than the counterparts under positive loads. Three-dimensional finite-element (FE) models were developed to simulate Sandwich panel flexural behavior and numerical results compared with the test data. Then, the verified FE model was used to analyze the influence of the arrangement of dumbbell-shaped SFCB connectors. Increased connector spacing from 550 to 650 mm was found to have an insignificant influence on load-deflection responses. Moreover, analytical solutions for deflection of Sandwich panels under combined axial-flexural load were obtained, in which the effect of slipping between the facade and structural wythes and shear deflection were considered. The predicted deflection at the ultimate load agreed well with the test results. This study provided a theoretical basis and design reference for FRP-jacketed steel-composite connectors in applications of Sandwich wall panels with large insulation layer thickness.