ANALYSIS OF MASONRY BUILDINGS EXPOSED TO EARTHQUAKE WITHIN IRAQI ZONES

Abstract

ABSTRACT

Masonry is considered as the oldest construction material still being used in nowadays construction. However, masonry building shows great sensitivity to the impact of earthquakes. Since most of the typical residential houses buildings in Iraq were designed using outdated building codes that did not account for horizontal seismic loads where only vertical loads were considered, it became necessary to introduce earthquake loads in the designs of these buildings. Due to the increase in seismic impact on Iraq in recent times, so it is important to study the behavior of the masonry building under the influence of earthquakes in order to assess the seismic performance and identify the weakness of this type of construction. This study focuses on assessing the seismic performance of residential buildings scattered throughout Iraq, which is subjected to seismic action. In this research a three-dimensional finite element model using ABAQUS 6-13 program was developed to represent, simulation and analysis of residential masonry buildings generally constructed in Iraq cities. The verification is carried out with two experimental models. The first verification done to select the best technique for modeling the masonry wall is by representing it in three techniques(micro modeling, simplified micro modeling, and macro modeling) where the macro modeling has proved its efficiency to modeling large models. The second verification is done with masonry room under the dynamic load was adopting macro modeling which has also close convergence for the simulation results to the II experimental data. In this study, a single room and three typical houses are simulated with the total dimension (5 x 20 m,10 x 10 m,10 x 18 m ) for one and two stories depends on the nonlinear behavior of the material and the nonlinear dynamic procedure (time history) in the analysis. The compressive strength of the masonry wall and nonlinear properties of the materials that are used in this study were obtained by testing samples in the laboratory which are used as an input data in the ABAQUS 6-13 program. Through the results of the prism tests of the masonry wall models, an equation is concluded to find the compressive strength of the masonry wall consisted of Iraqi building materials by using Artificial Neural Network (AAN). The design spectral responses acceleration parameters of the earthquake are adopted as 0.5g according to Iraqi zone. Two different acceleration is implemented, separately. El Centro earthquake happened in Southern California in1940 with a magnitude of Mw=5.4(peak ground acceleration PGA=3.50 m/ ) and Ali Al- Garbi earthquake happened in Maysan Province south of Iraq in 2012 with a magnitude Mw=4.9 (peak ground acceleration PGA=1.04 m/ ) are used as the input ground motion in this study. The involved result parameters are the maximum displacement, drift, and base shear which are compared with the requirements of seismic demand by the preliminary draft of Iraqi code and ASCE Standard ASCE/SEI 7-10. The results show that the models prove efficiency and stability against the effect of earthquakes, especially when the load is applied in1 the1Z (1long direction1) 1more thans1 the load applied in1 the1X (1short direction1) for all models. On the other hand, when the EL Centro earthquake load is applied on the models, the maximum displacement increased by 6-12%, drift increased by 22-29% and base shear increased by 29-32.96% more than when the Ali Al-Garbi earthquake load is applied on the models.