Concrete beams reinforced with fiber-reinforced polymer bars (FRP) are becoming widely used. The sustained deflections due to creep and shrinkage for these beams control the design due to the low modulus of elasticity of FRP bars. The current work presents a successful finite elements modeling for tests on FRP reinforced concrete beams along with study for some factors influencing the long-term deflection such as the reinforcement ratio and the type and the level of sustained load. Increasing the FRP reinforcement ratio results in reduction in the total sustained load deflection. Similarly, for the reduction in the sustained load level. Carbon FRP reinforced beams have the least total long-term deflections. FRP design codes such as ACI 440.1 R-06 and CSA-S806-02 provide simple equations for calculating the sustained deflection based on multiplicative factors. Also, the literature gives other equation for creep and shrinkage deflections based on multiplicative coefficients. The three original methods and the same methods with their amendments are verified against experimentally calibrated finite element models. The ACI440.1 R-06 method modified with Bischoff's effective moment of inertia is found to yield the best results. The current paper further modifies this method. The currently modified ACI440.1 R-06 with the effective moment of inertia as proposed by Bischoff is found to produce better accuracy for the calculations of the total sustained load deflections.

Nonlinear finite element analyses were performed on interior slab-column connections to investigate the effects on the punching strength of flat slabs. A total of twenty-seven threedimensional finite element models were constructed to represent large-scale flat plate slabs (2000 Â 2000 Â 155 mm) subjected to concentric and eccentric punching loads. The main parameters in this study were the eccentricity of the load, the opening size, the location of the opening relative to the direction of the transfer moment, and the configuration of the reinforcement adjacent to the opening that is used to compensate the cutting bars. The dimensions and reinforcement of the slab and column were kept constant. Predictions of the numerical models were in good agreement with experimental results published in the literature for slab column connections subjected to concentric loading. The numerical investigation showed that the presence of an opening adjacent to a column in a specimen subject to concentric loads could cause a significant reduction in the ultimate shear capacity which increases with the increase in the size of the opening. Specimens with 250 Â 250-mm size openings indicated a reduction of 35% in their ultimate shear strength capacity while specimens with 250 Â 450-mm size openings indicated a reduction of 45%. Specimens without openings subjected to load eccentricities of 112.5 and 225 mm resulted in a reduction in the load capacity of 18 and 28%, respectively. It was found that providing continuous bars adjacent to the opening to compensate the cutting areas of reinforcement could result in a considerable improvement in the serviceability of the slab represented by an increase the stiffness of the slab-column connection and no significant effect on the punching capacity for the case of concentric loads. Finite element analyses performed are in good agreement with provisions in the building code (e.g., ACI-318) for the case when the opening is located parallel to the direction of the principal moment and provide conservative values when the opening is in the upward side of the bending moment.

The paper presents comparison between the punching shear calculations from six different codes and two equations from the literature. It utilizes 257 punching tests data collected from the literature. The concrete strengths, f'c, range between 12.3 MPa and 68 MPa, the reinforcement ratios range between 0.2% and 5.01%, and the slab depths range between 80 mm and 500 mm. It is found that the smallest error is for CEB-FIP-90 and EC2-2004 while the largest error is for JSCE-2002 and ACI318-19. Also, modifications to one of the equations of the Egyptian reinforced concrete code and two of the equations of ACI318-19 code for calculating the punching strength of flat plates without shear reinforcements are presented. The modified Egyptian and ACI318-19 codes equations for punching strength are compared to the experimental data and good correlations are noticed. The obtained errors are lesser than those of the original codes equations and the average errors are on the conservative side.

Background A series of nonlinear finite element (FE) analyses was performed to evaluate the different design approaches available in the literature for design of reinforced concrete deep beam with large opening. Three finite element models were developed and analyzed using the computer software ATENA. The three FE models of the deep beams were made for details based on three different design approaches: (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978), (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006), and Strut and Tie method (STM) as per ACI 318-14 (ACI318 Committee, Building Code Requirements for Structural Concrete (ACI318-14), 2014). Results from the FE analyses were compared with the three approaches to evaluate the effect of different reinforcement details on the structural behavior of transfer deep beam with large opening. Results The service load deflection is the same for the three models. The stiffnesses of the designs of (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and STM reduce at a load higher than the ultimate design load while the (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) reduces stiffness at a load close to the ultimate design load. The deep beam designed according to (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) model starts cracking at load higher than the beam designed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) method. The deep beam detailed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) and (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) failed due to extensive shear cracks. The specimen detailed according to STM restores its capacity after initial failure. The three models satisfy the deflection limit. Conclusion It is found that the three design approaches give sufficient ultimate load capacity. The amount of reinforcement given by both (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) is the same. The reinforcement used by the STM method is higher than the other two methods. Additional reinforcement is needed to limit the crack widths. (Mansur, M. A., Design of reinforced concrete beams with web openings, (2006)) method gives lesser steel reinforcement requirement and higher failure load compared to the other two methods.