Mohammad Haji

Semnan University · Department of Structural Engineering

In recent years, recycled aggregate concrete (RAC) has been used as a suitable solution to solve the problems related to the disposal of construction waste and contribute to sustainable environmental development. However, RAC has defects such as low modulus of elasticity and low compressive bearing capacity, which limits the use of RAC only in non-...

Self-compacting concrete (SCC) is a highly flowable concrete that can fill complex formwork without the need for vibration. However, its high consistency can lead to various forms of instability, such as separation, bleeding, blockage, and settling. These instabilities can adversely affect the fresh and hardened properties of the concrete. Therefor...

The lack of adequate space for sewage sludge disposal has become a significant challenge in many countries. Landfilling and using sewage sludge as fertilizer in agricultural lands are the main methods for disposal. However, these methods can result in soil and groundwater contamination as well as heavy metal and microbial pollution in soil. An alte...

Due to the adverse effects of local corrosion of bars on the behavior of reinforced concrete structures, this problem has been investigated by many experimental studies. Reducing the cross-sectional area of steel bars due to corrosion diminishes the bearing capacity. On the other hand, weakening the interaction characteristics between bar and concr...

Shrinkage is the volume change of concrete without influence of external forces. Drying shrinkage, which occurs after the concrete hardening, is one of the most important causes of the cracking in concrete members. In addition to adverse effects on the appearance of concrete, cracks may reduce the strength and durability by increasing the permeabil...

Eccentrically braced frames are one of the most popular systems in buildings because they provide both high stiffness and ductility to the structure. Other systems such as moment frames and concentrically braced frames do not usually provide desirable stiffness and ductility, respectively. Steel shear walls are also popular systems in steel buildin...

The effects of high-strength steel (HSS) on the damage indices (DIs) of four special moment frames and three beam– column connection (BCC) specimens under cyclical loading were experimentally studied. The specimens with HSS rebars (with yield strengths of 500 MPa and 580 MPa) were designed and constructed based on the special seismic provisions of...

The reduction of the moisture content of concrete during the drying process reduces the concrete’s volume and causes it to shrink. In general, concrete shrinkage is a phenomenon that causes concrete volume to dwindle and can lead to durability problems. There are different types of this phenomenon, among them chemical shrinkage, autogenous shrinkag...

Fi­bre Re­in­forced Poly­mer (FRP) bars have great po­ten­tial for the strength­en­ing of the ex­ist­ing build­ings. They also can be used as a suit­able re­place­ment for steel bars. There­fore, the struc­tural be­hav­ior and pre­dict­ing the strength of the con­structed el­e­ments by this type of ma­te­r­ial is an im­por­tant is­sue. How­ever, th...

In this study, a fuzzy-logic based model for predicting the ultimate strength of FRP-confined circular RC columns is presented. The Adaptive Neuro-Fuzzy Inference System (ANFIS) model was generated using valid experimental data with seven input variables. Input parameters were considered in such a way that all the parameters affecting the compressi...

There are several methods for predicting experimental results such as empirical methods, elasticity and plasticity theory. Among these methods, the use of soft computing has been expanded due to good capabilities and high accuracy in predicting the target. Soft computing contains computational techniques and algorithms to provide useful solutions t...

Bridges are considered as part of the infrastructure of each country, which dedicate themselves a large part of the cost of a road construction and have a high degree of vulnerability to natural disasters such as earthquakes, especially bridge columns that carry loads from deck to foundations, so precise and safe design of bridges, especially colum...

The most important phenomenon that threatens the stability and health of structures in different parts of the world is the occurrence of an earthquake with varying intensity and magnitude. The most dangerous type of failure in structures is shear failure, which could occur in short columns. Consequently, such columns, with the potential of failure...

The columns are important structural members, which are mainly exposed to axial forces with or without bending moments, which their failure leads to destruction of the structure. Safety design and safety of the columns have always been the subject of the researchers. Short columns absorb more earthquake force due to the more ductility compared to s...

Short column phenomenon was one of effective cause in the structures with different floor at past earthquakes that floors of stories in this structures created in two or several heights. In the structures with difference in story level, major problems is due to discontinuity of floor diaphragm that causes significant changes in period, stiffness an...

High performance fiber-reinforced cement composite (HPFRCC) exhibits several desirable characteristics, such as strain-hardening, multiple fine cracks, energy dissipation and crack damage tolerance. These attractive properties have allowed the industry and researchers to apply HPFRCC mixtures successfully to various concrete structures. This paper...