Internal Steel Research Articles

Experimental hysteretic behavior of CFST column-foundation connections with novel detailing in embedded region

This paper presents a novel CFST column-foundation connection detail to improve stress transfer and damage control. To achieve this aim, seven specimens were created in the lab in three different configurations: exposed connection (base plate), embedded connection without reinforcement, and embedded connection with reinforcement. These specimens were subjected to cyclic lateral load and constant axial load tests. The effect of using internal reinforcement (including reinforcing anchor bar and internal tube) and external reinforcement (including shear studs, external diaphragm, and through diaphragm) in the embedded region on the reduction of the embedded depth was assessed. Performance indices of the tested connections, including the stiffness, lateral loading capacity, energy-dissipation capacity, ductility, and strain distribution of steel tubes, were analyzed based on hysteresis and pushover graphs. The test data demonstrated that all the specimens experienced flexural failure, and consequently, the local buckling of the steel tube was observed in all experiments with the exception of the specimen that had an exposed connection. The specimens with reinforcement in the embedded region had acceptable behavior with ductility coefficients higher than 4.8. The seismic response of the connection with the novel detail showed that the performance indices of the connection with reinforcing anchor rebars and reinforcing internal steel tube in the embedded region were considerably higher than those of the connection without reinforcement in the embedded region and the one in the exposed form. Moreover, the depth at which the connection is embedded was reduced by up to 0.7 times the diameter of the column due to the utilization of reinforcement in the embedded region.

Performance of steel tube reinforced concrete-filled weathering steel tubular members under lateral impact loading

Weathering steel tube is superior to mild steel tube in corrosion resistance, but it is less used in engineering projects due to its high price. To balance the performance and cost, mild inner steel tube reinforced concrete-filled weathering steel tube (STRCFWST) members are proposed in this study, and the lateral impact loading test is carried out. The impact responses of concrete-filled weathering steel tube (CFWST) members and STRCFWST members are studied and compared experimentally. It is indicated that the presence of the inner steel tube can remarkably enhance the impact resistance of STRCFWST members. The outer steel tube has a stronger influence over the impact resistance as compared to the inner steel tube. A constitutive model for the weathering steel is developed based on the material test results. The impact performances of STRCFWST, CFWST and conventional CFST members are compared and discussed using numerical simulation. Finally, parameter analysis of the impact performance of STRCFWST members is carried out by taking into account the actual stress state of bridge bents. The results show the proposed model can predict the mechanical behaviors of weathering steel, making it suitable for numerical modeling. The CFWST member suffers fracture failure a little earlier than the CFST member. A large diameter-thickness ratio is recommended for inner steel tubes on the premise of guaranteeing construction conditions. The optical area ratio of internal and external steel depends on the prices of weathering steel and mild steel, and the diameter ratio of inner and outer steel tube.

In-Depth Steel Crack Analysis Using Photoacoustic Imaging (PAI) with Machine Learning-Based Image Processing Techniques and Evaluating PAI-Based Internal Steel Crack Feasibility

Steel plays an indispensable role in our daily lives, permeating various products ranging from essential commodities and recreational gears to information technology devices and general household items. The meticulous evaluation of steel defects holds paramount importance to ensure the secure and dependable operation of the end products. Photoacoustic imaging (PAI) emerges as a promising modality for structural inspection in the realm of health monitoring applications. This study incorporates PAI experimentation to generate an image dataset and employs machine learning techniques to estimate the length and width of surface cracks. Furthermore, the research delves into the feasibility assessment of employing PAI to investigate internal cracks within a steel sample through a numerical simulation-based study. The study’s findings underscore the efficacy of the PAI in achieving precise surface crack detection, with an acceptable root mean square error (RMSE) of 0.63 ± 0.03. The simulation results undergo statistical analysis techniques, including the analysis of variance (ANOVA) test, to discern disparities between pristine samples and those featuring internal cracks at different locations. The results discern statistically significant distinctions in the simulated acoustic responses for samples with internal cracks of varying sizes at identical/different locations (p < 0.001). These results validate the capability of the proposed technique to differentiate between internal crack sizes and positions, establishing it as a viable method for internal crack detection in steel.

Salt scaling resistance of pre-cracked ultra-high performance concrete with the coupling of salt freeze-thaw and wet-dry cycles

Wet-dry cycles and cracking are unavoidable problems of concrete structures and reduce durability by enhancing the penetration of harmful ions and water, which may have a synergistic adverse influence with severe surface damage caused by salt freeze-thaw cycles. This study aims to investigate the salt scaling resistance of ultra-high performance concrete (UHPC) under multiple harsh environments including wet-dry cycles and pre-cracking. The relationship between workability, absorption behavior, and scaling resistance with fiber content increases is assessed. Mass loss, chloride binding behavior, pore structure, and pore morphology are analyzed to describe the influences of pre-cracking and wet-dry cycles. The results reveal that the workability of fresh concrete and the distribution of steel fibers are the key factors in determining the salt scaling resistance of UHPC. Pre-cracking and wet-dry cycles inhibit the rapid scaling damage of UHPC by accelerating chloride accumulation, which reduces the icing pressure of pore liquid and refining the micropores (<200 nm) capable of remaining non-frozen at low temperatures through the chemical binding of chloride. However, the combined effect of pre-cracking and wet-dry cycles can lead to the corrosion of internal steel fibers and more scaling damage, and the crack width should not be greater than 0.1 mm.

Cyclic behavior and numerical study of PRC coupling beam with steel truss floor slab

The coupling beam with small span-to-depth ratio is prone to brittle shear failure under the action of earthquake, so it can not play its role as the first line of defense against earthquake. Therefore, this paper proposes a method for calculating the shear bearing capacity of PRC-connected beams with reinforced truss floor plates. A more rational calculation model should be adopted based on its mechanical mechanism. In this study, ABAQUS finite element software is utilized to explore the parameters of PRC-connected beams with steel truss plates, including the span-to-height ratio, reinforcement ratio of the internal steel plate, diameter of upper and lower chord bars, and diameter of abdominal bars. The analysis shows that the span-to-height ratio, steel plate ratio and concrete compressive strength have a significant effect on the seismic behavior of PRC coupling beams with steel truss floor slab. Based on the softened tension-compression bar model combined with the multi-strip model, the theoretical calculation method of the shear capacity of PRC connected beams with steel truss bearing plates is derived. The results of comparison test and simulation verify the accuracy of the calculation results, and provide a design basis for the engineering application of PRC connected beams with steel truss floor plates.

Axial compression behavior of prefabricated T-section thin concrete encased steel short columns

A T-section thin concrete encased steel (T-TCES) column is proposed for the residual buildings, avoiding the convex corners in rooms. The required concrete cover thickness for concrete encased steel members specified in the existing codes is quite large, which is the key problem and to be solved in the proposed column by reducing the concrete covers, facilitating the transportation and installation. To evaluate the mechanical performances of the proposed columns, especially the local stability of the internal T-section steel with the obviously reduced concrete covers, tests of nine short column specimens were conducted under axial monotonic loading. Also, the finite element (FE) analysis was conducted and validated. The effect of the proportion of steel sectional area, concrete strength, stirrup spacing and the concrete encasement thickness outside the flange on the failure modes, load-displacement responses, load-strain responses and characteristic loads were obtained. According to the test and FE analysis results, the peak load can be improve by increasing concrete strength or the proportion of steel sectional area or decreasing the stirrup spacing. The T-TCES columns with low-grade concrete or small stirrup spacing or high proportion of steel sectional area have a better composite action between the internal steel and concrete. Increasing the thickness of the concrete encasement outside the flange can prevent the T-TCES column from cracking. The concrete encasement and reinforcement bars can restrain the internal steel buckling, and improve the steel strength of the composite column compared with the steel column. The calculation methods for the peak and design resistances of the T-TCES column were proposed and proved to show satisfactory accuracy. The simplified model of the load-displacement responses and the calculation methods of the axial stiffness are proposed and validated against the test results.

Eccentric compression behavior of circular concrete‐filled steel tubes reinforced with internal latticed steel angles

AbstractThe eccentric compression behavior of the CFSTs reinforced with inner latticed steel angles was experimentally investigated, and test results, such as the load–displacement curves, load‐strain curves, distributions of lateral deflection, and ultimate load, were obtained and analyzed. Test results showed the influence of the latticed steel angles on the ultimate load was not obvious when the steel consumption was relatively small, and the lateral deformation was not obvious when the compression load was smaller than 80% of the ultimate load. The corresponding finite element (FE) model was established and validated by the test results, and parametric analysis was also conducted subsequent to validation. The analysis results showed the contribution of latticed steel angles to the ultimate load would be diminished as the eccentric distance increases. Moreover, the design equations for the ultimate load were proposed based on the FE results, and the calculation results indicated the proposed design equations can predict the ultimate load conservatively and safely.

Assessment of structural performance of super large cross-section subsea RC shield tunnels: Emphasis on the combined effects of highly hydrostatic pressure and corrosion-induced deterioration

For the subsea reinforced concrete (RC) shield tunnels in China, the use of super large tunnel section and the presence of high hydrostatic pressure from seawater have been becoming increasingly common in practical engineering. However, owing to the combined effects of complex structural systems, extreme external loads and aggressive environments, it is a great challenge to sustain a reliable structural performance of these subsea shield tunnels within the prescribed service life. In this study, a novel approach for evaluating the structural safety of a deteriorated large-section subsea RC shield tunnel is presented with an emphasis on the spatial correlation and variation of corrosion damages and the impact of high hydrostatic pressure. Gumbel distributed random fields are established to simulate the spatial variability of steel corrosion in the segmental linings. A random field-based numerical model for the deteriorated RC segmental linings is developed in conjunction with the modeling of nonuniform steel corrosion and local-regional material degradation. In an illustrative example, the effects of the corrosion degree of internal and external steel reinforcements and the level of applied hydrostatic pressure on the structural safety of a large-section subsea RC shield tunnel are investigated.

Optimization of the Monitoring of Coal Spontaneous Combustion Degree Using a Distributed Fiber Optic Temperature Measurement System: Field Application and Evaluation

Coal spontaneous combustion (CSC) in gob not only leads to wasted resources and casualties, but also produces a lot of waste gas that pollutes the underground environment. Mastering the degree of CSC helps ensure that timely and effective control measures are taken. The real-time and accurate monitoring of temperature, as the primary indicator of the extent of CSC, is difficult due to the harsh and hidden environment of gob, resulting in a reduced ability to anticipate and prevent CSC. In this work, a complete distributed optical fiber temperature sensing system (DTSS) set with strong anti-damage ability was developed. The optical cable is protected by internal parallel steel cables and external protective pipes, which greatly improve the system’s reliability and integrity when used in gob. During its application in the Wangyun Coal Mine, an abnormal temperature rise in gob was discovered in time, and the effect of inhibitor spraying was monitored and evaluated. The degree of CSC in the gob was accurately identified, which shows that the work of coal mining can be targeted. This work is expected to improve early warning capability to prevent the risk of CSC in gob, and has promising applications.

Effects of Concrete Strength and CFRP Cloth Ratio on the Shear Performance of CFRP Cloth Strengthened RC Beams

A three-dimensional meso-scale numerical model, which considers (1) the concrete meso-structures, (2) the bond slip between concrete internal structures and steel bars, and (3) the stripping behavior of carbon fiber reinforced polymer (CFRP) cloth from the surface of the concrete component, is established to investigate the effects of concrete strength and the CFRP cloth ratio on the shear performance of reinforced concrete (RC) beams. On the basis of verifying the rationality of the shear failure model and the feasibility of the CFRP reinforcement simulation method, 30 orthogonally designed numerical models of six kinds of concrete strength and five kinds of CFRP cloth ratios were designed and established. Based on the numerical simulation results, this paper analyzes the damage evolution of the CFRP–concrete interface, the variation trend of CFRP strain along the height direction of beam, the failure mode, and the load-displacement curve. Results show the following: (1) With the increase of concrete strength grade and CFRP cloth ratio, the shear strength of RC beams strengthened with increases in CFRP cloth ratio, the influence range of concrete strength grade is 24–50%, and the influence range of the CFRP cloth ratio is 10–25%; (2) The improvement range decreases, and the improvement range of the concrete strength grade decreases, and the reduction range is about 20%; (3) Based on the simulation results, influences of concrete strength and CFRP cloth ratio on the shear strength of CFRP cloth-strengthened RC beams are quantitatively considered.

Strength of Hybrid Steel-BFRP Reinforced Concrete Beams with Openings in the D-Region Strengthened Internally and Externally

The opened beams always confused the designers due to the guidelines missing. In this research, six hybrid beams reinforced with mixed steel and basalt fiber-reinforced polymer (BFRP) bars and having constant cross-sections of 150 mm × 300 mm and a clear span of 1800 mm were cast and tested under a four-point loading setup. Generally, five beams had symmetrical rectangular openings with dimensions of 150 mm × 250 mm located at a distance of 250 mm (equivalent to the beam effective depth) from the beam support, while an additional solid beam served as a control. The studied parameters included the effect of using internal reinforcement (steel or BFRP bars) provided adjacent to the opening sides or by incorporating an external BFRP sheet around the opening corners. Also, double enhancement with internal steel reinforcement bars together with external strengthening BFRP sheet was investigated. The relevant results showed that the opened beam without enhancement lost 75% of the maximum load compared with the solid beam. Placing internal steel or BFRP bars around the openings increased the maximum load by 62% and 60%, respectively, compared to the non-enhanced opened beams. Using an external BFRP sheet to strengthen the opening corners of the beam enhanced the maximum load by 76% compared with the non-enhanced opened beam. Consequently, by combining both the internal steel reinforcement and external BFRP sheet around the openings, the maximum load increased by 137% compared with the non-enhanced opened beam. Ultimately, a numerical analysis of the three-dimensional finite element model was performed to confirm the experimental findings, and the relevant results showed compatibility correlations with the experimental ones. Also, the effect of various parameters such as BFRP reinforcement ratio and number of BFRP sheet layers around the openings was investigated by adapting the validated numerical model.

Investigation of the in-plane mechanical behavior of timber and steel–timber composite arches

This research investigates the structural characteristics of steel-timber composite (STC) structures through a comprehensive investigation involving five-point bending tests conducted on both the timber arch and the STC arch. The proposed STC arch configuration employs glulam panels bonded to the steel arch using adhesive, effectively restraining the internal steel components and mitigating the risk of buckling. By analyzing the test results, mechanical behaviors of the specimens were observed, including failure modes, load–displacement curves, and load–strain responses. Notably, the ultimate load-bearing capacity of the STC arch exhibited an approximate 28.44% increase compared to that of the timber arch, while maintaining a steel ratio of 10%. The steel ratio, defined as the proportion between the cross-sectional area of the H-shaped steel and the total cross-sectional area, was a critical factor to evaluate both the improvement effect and economic benefits. Additionally, employing finite element models, the influence of steel strength, timber strength, and steel ratio on the ultimate load-bearing capacity was demonstrated. Furthermore, the proposed analytical methodologies can be effectively employed to evaluate the mechanical performance of the STC arch, offering a valuable framework for assessment.

Impact Analysis of a Commercial Airplane Over a Nuclear Spent Fuel Dry Storage Cask

The evaluation of the structural integrity of a vertical cask that is used for spent nuclear fuel dry storage is reported. The cask diameter and height are 3.566 m (140 in.) and 5.28 m (207.75 in.), respectively. The analysis focuses on such a cask being impacted by a commercial airplane. The dry storage container standards, which are under evaluation and approval by the U.S. Nuclear Regulatory Commission, are considered. The storage container inner basket is made of a stainless steel plate cylinder. It is located within an outer shell. The last one is manufactured with concrete and has internal and external steel liners. The commercial airplane considered in this analysis has a length of 40.39 m (132 ft, 6 in.). Its wingspan and height are 35.23 m (115 ft, 7 in.) and 11.98 m (39 ft, 4 in.), respectively. Its take-off weight is 81 090 kg (178 773 lb). An explicit analysis with the finite element method is carried out. The impact angles were 0, 30, 45, and 60 deg with respect to the horizontal. The mesh of the domain has 1 104 229 hexahedral elements and 1 516 156 nodes. Initially, all the structures are considered without restrictions and free of stresses. The vertical container for dry storage is at rest on a rigid concrete base. The aircraft velocity is 234 m/s or 842 km/h (523 mph). The impact event is simulated in an interval of 0.03 s. The maximum principal stress fields show that there are points at the lid of the container that are above the elastic limit and the ultimate strength. Under these conditions, brittle failure is expected.

Experimental and Analytical Study on the Axial Behavior of Circular High-Strength Concrete Columns with Hybrid Carbon Fibers and Steel Confinement System

This paper describes a work that examines a new solution to the problem that arises from the relatively high amount of transverse reinforcement required in HSC columns. It presents an alternative to common transverse steel reinforcement, a dual system comprising steel ties and a carbon-fiber mesh (CFM) applied internally together with steel ties. The behavior of the proposed system was examined in this work in a series of twelve laboratory tests of circular stub column specimens. The experiments performed in this work focused on the columns’ load and displacement capacities. The tests were planned with the aid of an analytical model that was originally developed for a hybrid system of external fiber-reinforced polymer (FRP) sheets and internal steel, and was adapted for the current system. An analysis of the results shows that for a given amount of conventional transverse steel, the application of the carbon-fiber meshes adds efficiency to the rebar confinement system, in terms of both the load bearing capacity and the ductility, and for specimens with the hybrid confinement system, the higher the carbon fiber amount the larger the ductility improvement. Furthermore, fair to good agreement was observed between the model and the measured stress–strain curves, especially those of the peak stresses. Based on the above findings and the added benefit of fire resistance, the hybrid method appears to be promising for confining HSC columns.

Behaviour of small-scale glulam timber connections with slotted-in steel plates and dowel-type fasteners reinforced with self-tapping screws

Braced frames are a common lateral force-resisting system in mass timber structures. In timber braced frames, timber-steel dowel connections are relied upon to provide ductility and energy dissipation capacity under earthquake loads. However, the ductility and energy dissipation capacity of these connections can be limited by the onset of a brittle failure mechanism (e.g., row-shear or group tear-out) prior to significant dowel yielding. This paper presents an experimental campaign investigating the structural performance of timber-steel dowelled connections reinforced with self-tapping screws. Twelve connections were tested; with 8 tested under monotonic loading and 4 tested under a cyclic loading regime. The tested connections included two different fastener diameters of 11 mm and 16 mm, with one or two internal steel plates, both with and without reinforcing screws designed to prevent brittle shear failure. The results demonstrate that the reinforcing screws are most effective for improving the ductility and energy dissipation for connections with similar design values of dowel yield and row shear capacities. In addition, the increases in ductility and energy dissipation with reinforcement were greatest for connections with high slenderness (defined as the ratio of dowel diameter to timber thickness) dowels. There was little improvement in the ductility of connections whose design capacity was dominated by row shear, although there was improvement in the energy dissipation of the connections. Overall, results of this study demonstrate the potential for using self-tapping screws to reinforce steel dowel connections and improve the seismic performance of mass timber braced frames.

Study on the Stress Performance of an Incompletely Prefabricated Profile Steel Reactive Powder Concrete Column in High-Rise Modular Buildings

In this study, 11 PSRPC column specimens were designed and fabricated in order to investigate the stressing performance of incompletely prefabricated steel reactive powder concrete (PSRPC) columns and were subjected to static loading tests. The effects of the strength grade and steel content of reactive powder concrete (RPC) on the axial compression performance of PSRPC columns and the effects of the steel content and eccentricity on the eccentricity performance of PSRPC columns were investigated. The test results show that the external prefabricated RPC, the internal steel section and the internal cast-in-place RPC of the PSRPC column work well together. The damage morphology of the specimens and the load–displacement and strain relationships were analysed, and the damage mechanism and the main factors influencing the compressive load capacity of the PSRPC columns were investigated. The test results are compared with the calculation results of the Chinese code (JGJ 138-2016) and the European and American codes (AISC-LRFD), and the applicability of the existing codes is discussed. Based on the hoop restraint action and limit state design method, formulae for calculating the axial and partial compression load capacity of PSRPC columns were established. The calculated values were in good agreement with the test values, and the calculation errors were within 10%.

Mechanical behavior of GFRP-recycled concrete-steel multitube concrete columns under axial compression

This paper proposed a novel GFRP-recycled concrete-steel multitube concrete column (RA-MTCC), which consisted of an external circular GFRP tube, a group of small internal steel tubes in a circular array, and recycled aggregate concrete filling for all the space inside of these tubes. The mechanical behavior of eleven specimens were investigated under uniaxial compressive test considering parameters of the GFRP tube thickness, the configurations of internal steel tubes, the strength and the replacement ratio of recycled coarse aggregates (RCAs). Test results indicated that: (1) the replacement ratio of RCAs had no significant impact on the failure mode and ultimate load bearing capacity but noticeable adverse effect on the stiffness of RA-MTCCs; (2) the small internal steel tube could significantly increase the ultimate load bearing capacity and stiffness of RA-MTCCs, with a maximum enhancement of 82% and 114%, respectively; (3) specimens with GFRP outside exhibited excellent ductility behavior due to the effective confinement provided by GFRP jacket and steel tubes. An analytical model considering the replacement ratio of RCAs was proposed and verified with the present test results. The predicted results showed that the proposed model could accurately predict the full range stress–strain response of RA-MTCCs. Finally, based on the proposed analytical model, a simplified calculation formula for the ultimate bearing capacity of RA-MTCC was proposed.

Parametric investigation of continuous beams strengthened with near surface mounted FRP bars

This study evaluates the near surface mounted fiber-reinforced polymer (FRP) reinforcement technique for strengthening continuous reinforced concrete beams. A three-dimensional finite element model was developed and validated with a recent experimental study. The model incorporates robust features, including concrete nonlinear behavior, debonding and slipping of FRP bars, and various failures. It was able to capture the ultimate load (Pu) with maximum deviation of 7%, beam’s load–deflection curves, load–strain responses in rebar and concrete, and various failure modes. A parametric study was conducted and showed that failure mode changes from concrete shear to FRP bar debonding at concrete compressive strength fc’of 20–30 MPa, with a 26–52% increase in Pu relative to the un-strengthened beam. Varying the hogging/sagging FRP reinforcement ratio (ρh/ρs) from zero to 2.0 results in a 39% increase in Pu and a change of failure mode. A value of 1.5 is recommended for ρh/ρs. Also, the synergistic effects of NSM FRP and internal steel reinforcements were studied. An FRP bar length in the hogging and sagging zones of 80% the beam span was found to be sufficient to mitigate debonding and thus is recommended. Pu did not vary significantly with the span ratio for two-span continuous beams. A design expression for the debonding strain in FRP bars based on the American Concrete Institute design guide was assessed and a further refined model is developed.

Behavior of TOBs bolted curved T-stubs to steel tube with internal stiffener

Internal stiffeners can effectively enhance the structural performance of Thread-fixed One-side Bolts (TOBs) bolted steel beam to circular tubular column connection by increasing the out-of-plane flexural capacity of the column wall and the anchorage length of the TOBs. Five TOBs bolted T-stubs to circular steel tube specimens with three different forms of internal stiffeners, substituting the tension zone of beam to column joint, were designed and tested in this paper to determine a reasonable form for the internal stiffener. Test results showed that the strengthened specimen could prevent undesirable plastic deformation of tube wall and hole threads shear failure. The Type-II stiffener consisting of an internal steel tube with a longitudinal rib performed the optimum strengthening effect. Finite Element analysis is conducted to analyze phenomena that could not be directly observed during the test. It is found that the hole threads in the stiffener wall provide considerable anchorage force, which may be larger than that provided by the hole threads in the steel tube in the late loading stage. Parametric studies are also conducted on the wall thickness, rib thickness, and installation gap of the Type-II stiffener. The results show that the stiffener wall thickness is the main factor affecting the strengthening effect and the installation gap should be controlled within 2 mm to ensure the strengthening effect. Finally, design approaches are presented to predict the carrying capacity of the strengthened connection, and the validation against the test and FE results shows reliability and stability.

Experimental investigation on the behavior of fly-ash based geopolymer reinforced concrete beams strengthened with CFRP

Recently, the demand for strengthening and rehabilitation of existing RC structures has increased due to the corrosion of internal steel reinforcement, variations in temperature, and increasing loading. As a result, several experimental studies have been performed to investigate the structural behaviour of strengthening RC beams with CFRP sheets, but few for GPC beams; therefore, this investigation focuses on the behaviour of strengthening GPC beams with CFRP sheets. In this experimental work, a set of ten specimen beams with the same cross section of 100 × 250 mm and 850 mm length with a 750 mm clear span were cast in two groups of five beams each. First group (flexural group) to study the flexural behavior, and the second one for the shear behaviour (shear group). In each group, the first beam was carried out as an RC control beam and the second as a GPC control beam without strengthening, while the other three beams were cast as GPC beams and strengthened with various schemes of CFRP sheets. All specimens were tested up to failure under two-sided static loading (four-point bending). The first cracking, yielding, and ultimate failure loads, the deflection values at midspan, the longitudinal bar strain, and the concrete strain were recorded for all tested specimens. The experimental results indicated that the Flextural Strengthening of GPC with CFRP sheet increased the First Cracking, yield and ultimate load capacity by 25.33%, 15.3% and 15% respectively, as well as, deflection was decreased by 16% on average while ductility and toughness have improved by 10% and 12% on average compared to R.C Beam.On the other side, the Shear Strengthening of GPC with CFRP strips increased the First Cracking, yield and ultimate load by 43%, 70% and 68% respectively, as well as, shear ductility has improved by 8% on average compared to R.C Beam. Overall, the different schemes of externally bound CFRP sheets have improved the flexural and shear behaviour of GPC beams.