To build a safe and reliable world for all, buildings and structures must be designedwith the capability of withstanding explosions. When an explosion occurs, it inducesa sudden high-impact dynamic air-blast loading on its surroundings. Studiesand real-life cases have shown that such loading causes a brittle, shear failure inreinforced concrete (RC) elements. To prevent this, one must understand how factorssuch as concrete material properties, boundary conditions, and characteristicsof the load affect the failure mode. It is still not fully comprehended how to predictthe crack propagation and avoid shear failure of such elements.As a continuation of previously conducted studies on blast-loaded RC elements,the aim of this thesis is to contribute to the understanding of what conditionsinduce flexural or shear failure in reinforced concrete. The analysis is conducted byimproving a previously developed numerical model (Frank and Fristedt 2021) toaccurately represent an RC beam under dynamic impact loading in terms of crackpropagation pattern, vertical displacement, and support reaction force. To ensureaccuracy for this purpose, the model is calibrated and validated against data fromprevious shock tube testing (Magnusson and Hallgren 2000). Following this, inthe late spring of 2024, the Swedish Defence Research Agency (FOI) will conductfurther shock tube testing and study new setup variations. The main studies inthis thesis are therefore carried out by applying the calibrated model to this newexperimental setup and studying the effects of varied impulse intensity, load rate,and boundary conditions. The effects are mainly analyzed in terms of verticaldisplacement and total support reaction force.The results show a tendency for RC beams with fixed boundary conditions toexperience more web-shear failure than with simply supported conditions. A greatersupport restriction of rotational movement causes a greater support reaction forceand less maximum displacement. This makes the fixed RC beams prone to a moredirect shear failure. Similarly, beams with the same load magnitude but a higherreinforcement ratio fail in web-shear, while RC beams with a lower reinforcementratio fail in flexure-shear. Further, it is found that an increased load rate induceshigher support reaction force and vertical displacement at a faster rate. Comparedto the beams subjected to a lower load rate, the critical shear crack appears closerto the support with a higher inclination. An increased impulse magnitude, however,does not influence the support reaction or crack propagation.