## 1 Introduction  
The use of fiber reinforced polymer (FRP) to strengthen concrete structural members has greatly increased in recent decades [1; 2]. Various advanced composite fabrics are utilized for this reinforcing technique instead of jacketing by the steel plate because the FRP possesses the features of high strength, lightweight, corrosion resistance, and easy handling. All of these advantages make fabric composites an attractive material for the application of repairing and strengthening the concrete members. Therefore, extensive research has been conducted to study the performance of concrete members strengthened with FRP composites. Research results have demonstrated that the FRP composites can considerably enhance the flexural and shear strength of reinforced concrete beams [3], as well as the ductility of reinforced concrete columns [4]. The FRP composites bonding technique has proven to be more cost-effective and easier in construction than other means.  
Two-way reinforced concrete slabs in flat plate floor systems may fail in shear when the slabs are subjected to concentrated loads. Such punching shear failure occurs suddenly with almost no warning, involving a truncated cone around the column or the loaded area [5; 6]. Generally, the load to cause punching shear failure of a flat slab is less than that for the flexural failure. Therefore, the punching shear strength should be increased to exclude the punching shear failure. Some experimental studies have been conducted to increase the load-carrying capacity of slabs by being strengthened with FRP composite. [PERSON] and [PERSON] [7] tested reinforced concrete slab-column connections strengthened with glass fiber reinforced polymer (GFRP) laminates. Their test results demonstrated that GFRP effectively increased the punching shear capacity of the slab-column connections, especially for the slabs with low compressive strength of concrete and reinforcement ratio. They found that ACI code significantly underestimated the test results. [PERSON] et al. [8] tested two-way flat slabs strengthened by FRP fans where FRP fans were anchored at their ends like a fan. They observed that the strengthening could increase the shear capacity of the slab and might change the failure mode from shear to shear-flexural or flexural. [PERSON] et al. [9] studied the application of non-prestressed and prestressed carbon fiber reinforced polymer (CFRP) plates on concrete column-slab connections. Four strips of CFRP plates were bonded on the tension surface of the slabs. They found that prestressed CFRP plates enhanced the serviceability such as the deflection and cracking. [PERSON] et al. [10] used CFRP sheets to strengthen reinforced concrete slabs. Strips of CFRP sheets in two perpendicular directions were bonded to the bottom of the slabs. Their tests concluded that the use of CFRP sheets improved the punching shear strength of slabs.  
Recently, studies of slab systems have been extended to the topics related to environmental impact and sustainability, such as the sensitivity analysis of the life cycle assessment [11] and the development of metamodels based on deep-learning methods [12].  
This study presents the experimental and analytical investigations for the use of carbon FRP laminates to strengthen the slab-column connections. The effect of CFRP laminates bonded to the slabs is explored in terms of the mode of failure, load-deflection characteristics, punching shear strength, and stiffness.