Composite concrete–steel sections are widely used in flooring and decking systems in buildings and bridges. Concrete decks form cracks at negative moment regions and remain uncracked at the positive ones. Finite-element (FE) analyses of beams composed of concrete–steel sections must take the change in the composite section properties into consideration on the basis of the level of cracks in the concrete deck. Commercial FE software packages use linear elastic analysis for calculating the moment and shear force distributions in beams loaded with gravitational loads, with no consideration of the level of cracking in the concrete slab at the negative moment regions. A FE modelling technique for beams with concrete–steel sections was developed by using FE software packages to estimate the internal loadings necessary for the design process. The results from the proposed FE technique were compared with experimental data on continuous and simply supported beams reported by other researchers. It was found that consideration of the concrete deck longitudinal reinforcement in the modelling of a composite section over negative moment regions is necessary for identifying flexural properties, resulting in better accuracy of the structural analysis outcomes. The proposed modelling technique estimated deflection in the tested beams with only 7% error with respect to the experimentally measured deflection.

This research is part of project conducted to build energy-efficient houses. It is suggested to replace normal weight reinforced concrete slabs and the thermal insulation layer with structural foamed concrete slabs. As strength requirements were previously investigated, the long-term deflections of six foamed concrete slabs with various reinforcement schemes are studied in this paper. First, deflection under own weight was measured for 36 days. Then, a load of 3 kN/m² was applied and the deflection was measured continuously over one year. Afterwards, part of the applied load was removed, and specimens were under own weight and 1.7 kN/m² for another year and then tested for flexural capacity. It is concluded that foamed concrete slabs should not be reinforced with glass fiber grid due to their insufficient flexural strength although these slabs had the least deflections. Reinforcing foamed concrete slabs with steel is suitable for structural use. A modification on effective moment of inertia equation available in literature is proposed to predict deflection that can represent the experimental outcomes. It is also found that the deflection results of foamed concrete slabs satisfy the codes limitations. Moreover, it is concluded that more specimens should be tested under various geometric and reinforcement details.

The progressive collapse resistance of reinforced concrete (RC) frames in which a middle column has been removed has been investigated by many researchers. However, previous experimental and computational studies have focused mainly on the catenary action provided by longitudinal reinforcement in the beams spanning the missing column. This study investigated the contribution of infill walls. Finite-element analysis was used after calibrating a reference model using test results reported by other researchers. Models were developed for a RC frame with and without infill walls. An equivalent strut was used in the infill walls to allow the removed column load to be transferred through the struts instead of developing catenary action in the beams. A simplified model of the progressive collapse resistance of frames with infill walls was then derived to estimate the peak strength provided by the infill wall under the scenario of middle-column removal.

The use of both structural steel and reinforced concrete is common in civil and military infrastructure projects. Anchorage plays a crucial role in these systems, serving as the key element that connects structural components and secures attachments within complex composite structures. This research focuses on evaluating the performance of steel–concrete column connections under the combined effects of lateral loading and fire exposure. Additionally, the study investigates the use of carbon fiber-reinforced polymers (CFRP) for strengthening and repairing these connections. The research methodology combines experimental testing and finite-element modeling to achieve its objectives. First, experimental investigation was carried out to test two groups of steel-reinforced concrete column specimens, each group made of three specimens. The first group specimens were designed based on special moment frame (SMF) detailing, and the other group specimens were designed based on intermediate moment frame (IMF) detailing. These two types of design were selected based on seismic demands, with SMFs offering high ductility and resilience for severe earthquakes and IMFs providing a cost-effective solution for moderate seismic zones, both benefiting from ongoing innovations in connection detailing and design approaches. Then, finite-element analysis was conducted to model the test specimens. High-fidelity finite-element modeling was conducted using ANSYS program, which included three-dimensional coupled thermal-stress analyses for the six tested specimens and incorporated nonlinear temperature-dependent materials characteristics of each component and the interfaces. Both the experimental and numerical results of this study show that fire has a more noticeable effect on displacement compared to the peak capacities of both types of specimens. Fire exposure results in a larger reduction in the initial residual lateral stiffness of the SMF specimens when compared to IMF specimens. While the effect of CFRP wraps on initial residual lateral stiffness was consistent for all specimens, it caused more improvement for the IMF specimen in terms of post-fire ductility when compared to SMF specimens. This exploratory study confirms the need for further research on the effect of fire on the concrete–steel anchorage zones.