Reinforced Concrete buildings with 3 to 5 stories are common structures in Iraq. Recently and due to several earthquakes taking place at the borders and/or even inside Iraq, these structures are under the action of long-term cyclic loadings from these earthquakes. A major structural element in these RC structures is the beam-column connection which observes the energy from the earthquake shocks. Consequently, understanding the performance of these joints under reversed cyclic loading produced from repeating earthquake became necessary to understand the real capacity and behavior of these connections. One model is developed using the finite element software ABAQUS to represent a possible type of beam-column joint in any typical structure undergoing reversed-cyclic load from earthquakes. The suggested model offers a simple demonstration of the plastic mechanisms which determines joint behavior under shear loading created from repeating seismic actions. The model is subjected to reversed cyclic loading made from the peak value of actual earthquake applied at different timings after the joint reach yielding in the longitudinal reinforcement. The purpose of the study is to determine the energy and the remaining shear strength that the joint holds after it reaches the yield point after such reversed cycles. Shear capacity and deformations of the columns are calculated after each applied cycle gained from the earthquake and accumulated to know the total deformation after the cycles and to understand the response of that joint after each cycle and at the end. The results of this particular model indicate that it is suitable to be used in demonstrating the response of such type of joint undergoing cyclic loading.

The evaluation of the damage caused by seismic action, to existing bridges has received an important attention in recent years, because it is the first step towards reducing casualties and economic losses. All reinforced concrete bridges in Iraq which have been constructed were designed by outdated building codes that did not account for large seismic activities and were designed with typical transverse reinforcement spacing that far exceed today's standards and are therefore insufficient to resist the laterally applied loads. The evaluation of the damage caused by earthquakes in existing bridges became necessary in Iraq especially after the huge earthquakes in the neighbor countries such as Bam earthquake in Iran on 26 December 2003 with a magnitude Mw= 6.6 and Van Earthquake in Turkey on 23 October 2011 with a magnitude Mw=7.2. Therefore, this finite element analysis will involve modeling a typical scaled version of a reinforced concrete bridge pier that is usually being used in typical bridges in Iraq. The pier will have a vertical load applied at the top to simulate the dead loads of the superstructure and will also be subjected to seismic loading. The main objective of this study is to investigate the damage in the typical reinforced concrete bridge pier under seismic loads of intensity same as that happened in the area around Iraq and see whether it will support such an earthquake or not.

Bridges are critical to most transportation systems, especially in times of crisis; however, as highly visible and accessible structures, they are also potential targets for terrorist attacks. An understanding of the performance of bridges subjected to blast loads is of critical importance to prevent progressive collapse of such structures that could lead to a catastrophic loss of life. The current research focuses on investigating the behaviour of bridge decks under blast loads from various explosions. The bridge in this investigation is the Sheikh Saad Bridge in Wassit Province, Iraq, whose deck is made of simply supported spans with two types of prestressed concrete girders. Both spans were accurately modelled using the finite element software Abaqus/Explicit, and both concrete and steel mechanical material properties were modified to match the properties under high strain rate conditions of the blast analysis. The latest element deletion technique of the built-in Concrete Damaged Plasticity (CDP) model (available since Abaqus 2019) was used to provide a realistic simulation of concrete damage and spalling. The model was separately subjected to various explosive charges placed at different locations above or below the bridge deck in order to determine the influence of size and location of blast on the bridge superstructure, detailed results and the relevant conclusions are thus presented. Overall, the modelling managed to successfully simulate the blast load response and the cracking propagation within the damaged deck components.

A method of using waves instead of modes for analyzing the seismic response of buildings is presented. Instead of using the general procedure of response spectra to quantify the seismic hazard of a building a wave response function is used. An important aspect of this approach is that the wave model can describe building response using only four parameters namely, the stiffness, wave speed, time delay, and normalized distance and are shown to be enough to describe the full building response. The method presented is limited to responses due to ground motions from earthquakes and the building response to be predominately in shear. The wave analysis method proposed can be used for variable structure stiffness with uniform and non-uniform damping cases. Comparison using response spectra for a typical shear building is presented and discussed. The strength of the wave function approach is that it provides more information about the response of the specific shear buildings than the response spectra approach. As one of the findings from the analysis using waves is that the maximum strain in a shear building with variable stiffness and non-zero damping is related to the maximum velocity of the ground motion and not the maximum acceleration.