Sharif Digital Repository

Reinforced concrete is one of the most important structural materials used in the construction industry worldwide. Nevertheless, certain physical and chemical factors in the service environment can contribute to its deterioration and failure. One of the most significant factors is the reinforcing steel bar (rebar) corrosion. In order to minimize the rebars corrosion, different kinds of coatings were investigated and evaluated by scientists. In this investigation comparative studies were performed on two different kinds of coated rebars (zinc-rich epoxy and polyamide epoxy coated rebars) and uncoated rebar. In order to evaluate these reinforced concretes, the adhesion, durability, thickness... 

The cathodic protection system was employed for protection of the reinforced concrete of the foundations using the mixed metal oxide anodes embedded in concrete for current distribution. . In this system, after required measurements for zone design calculation of the surfaces current density, IR drop and the circuit’s resistance has been measured. After specifying the appropriate locations for the reference Electrodes (Ag/AgCl) in order for cathodic protection monitoring these three electrodes are installed in three protection zones. After design and supply of all the materials, the installation was started. The protection criterion of steel in concrete was studied and all the measured... 

Many of the major structure over coastal waters in the Kish Island due to the aggressive condition are showing signs of reinforcement corrosion. Recent advances in the development of anodes make it practical to use zinc galvanic cathodic protection to protect this structure in this area. Five anode systems were tested on several samples as, (1) zinc metal spray applied by arc-spraying on the concrete, (2) a zinc foil with conductive adhesive backing, (3) a system of zinc mesh and grout jacket, (4) a system of zinc mesh and compression panels, and (5) a bulk zinc. These anodes are set up to comparison the effects of potential and current over the zinc galvanic cathodic protection during 4... 

The rehabilitation of old structures holds a lot of importance, as many structures with a life span of over 30 years are prone to severe damage and even collapse. To overcome this problem, the use of FRP sheets to strengthen structures is suggested. RC-arches have been used in many structures such as bridges and require specific consideration in terms of strengthening. So far, the influence of the number of FRP layers and location, the height of arch and percentage of reinforcement on strengthened arch behavior have not been investigated. In this research, reinforced concrete arch members strengthened with GFRP and CFRP were investigated. A total of 28 Specimens, including four... 

Despite extensive studies on the behavior of reinforced concrete slabs, especially those reinforced with steel rebars, no comprehensive studies have been conducted on the behavior of concrete slabs reinforced with FRP rebars. Therefore, there are some ambiguities regarding the tensile and compressive behavior of these rebars in the load-bearing capacity of reinforced concrete slabs (depending on their amount in the slab and their combination with steel rebars). Hence, in this study, in order to ensure the accuracy of numerical simulations, the numerical 3D simulation of a one-way concrete slab reinforced with tensile FRP rebars was performed using the finite element Abaqus software.... 

The benefits of fiber reinforced concrete (FRC) have been thoroughly investigated. Much of this work has focused on polypropylene FRC notched beams. Data on the bending behavior of beams with side notch is scarce. A pilot investigation on the compressive behavior of macro-synthetic FRC and on the splitting tensile strength of FRC was carried out. Twenty beam specimens with two different strength of 35 and 60 MPa was tested. The beams dimensions were 15*15*55 centimeter and they were notched at the bottom at mid and side span. Two different notch depth of 5 and 7.5 centimeter was implemented. At the end it was found out addition of fiber decreases compressive strength of 35 Mega Pascal... 

A brief overview of the proposed research, its aims, engineering relevance and applications; as well as expected achievements compared to the present state of the art:The plastic hinge length and ultimate drift calculations of frames are required in the performance based design of reinforce concrete structure. FRP-confinement increases the column’s shear resistance and ductility. FRP-confinement prevents concrete cover from spalling and increases the inelastic deformability of concrete in the potential plastic hinge region. GU et al. 2012 [24] studied the existing experimental results of confinement effects on the plastic hinge length. Mortezaei and Ronagh, 2012 [25], studied the plastic... 

Global collapse in earthquake engineering refers to the inability of a structural system to sustain gravity loads when subjected to seismic excitation. Dynamic instability phenomena in exist buildings have a key position and for this reason strict criteria in structural seismic assessing codes presented for avoiding this phenomena. At this study, dynamic instability of five designed concrete buildings with moment frame system, mixed up 3, 6, 9, 12 and 15 story building, are investigated. P-delta effects, deterioration in strength and stiffness and cyclic deterioration in structural components considered in this investigation. For modeling nonlinear behavior of elements, experimental results... 

Many reinforced concrete frame buildings with masonry partitions have been built all around the world. Observations from past earthquakes show that the partitions can endanger the life of buildings occupants and lead to significant damage and loss. Failure of the partitions can be caused by dynamic vibrations and in-plane and out-of-plane loads/displacements. The interaction between in-plane and out-of-plan behaviors and location of partitions, nonlinearity and higher modes of the structures could affect the out-of- plane seismic demands on partitions. Therefore, there is a need for a comprehensive assessment in order to limit the loss in buildings with masonry partitions. This research... 

Since the main weight of structures comes from the weight of floor systems, it is desirable to use tin and light floor system in order to reduce gravity and seismic force induced in the structure. However architectural aspects limit the application of short spans in the structural system. The objective of this work was to analyze the adequacy of a design method widely used in the modeling of waffle slabs interaction with steel columns as its supports in steel frames, and to verify if it represents the slab behavior satisfactorily. A real scale waffle slab was laid on a steel column and submitted to service loads. Subsequently it was analyzed with FE method for measuring specific stress,... 

Building weight reducing idea and implementation of Lightweight Structures were always attractive for structural engineering experts, scholars and researchers around the world and its proven effects on improving behavior and reducing the forces acting on the structure, has urged researchers to create new designs. Concrete slabs are of a significant portion of the overall weight of the structure. Nowadays, waffle slabs are a demand for structural designers, as a consequence of architectural design evolution and new building management concepts, in spite of its laborious numerical modeling. The objective of this work was to analyze the adequacy of a design method widely used in the modeling of... 

Concentric steel braces and brace-type dampers are often applied to the upgrading of reinforced concrete frames subjected to lateral loads. These braces may develop High axial tension forces, and transferring them appropriately to the existing beam– Column joints is a key challenge. This paper investigates a solution for connecting the end-plate of the steel brace with the frame, using shear-key plates fixed to the concrete with anchor bolts, and a low friction material inserted between the end-plates and the shear-key plates. The presence of the low friction material impedes the development of tension forces in the anchor bolts and ensures that they are basically subjected to shear forces.... 

Although considerable researches have been conducted on strengthening RC structures using FRP method during past years, a few researches have been reported on RC arch or curved structures strengthened by FRP. In this study, behavior of RC arches strengthened by FRP strips is investigated. The behavior of strengthened RC arches under gravitational load is analyzed using finite elements method. The arches are modeled by appropriate software in order to evaluate the behavior. The structural behavior of arches is more complicated. So, the estimation of the effect of strengthening using FRP technique on such structures is hard in comparison with traditional RC beams. In this study, the effect of... 

Reinforced concrete (RC) column in building often needs strengthening either due to defects in the column themselves, having to support higher loads than those foreseen in the initial design of the structure or as the result of ageing or accidental damage such as earthquake force. The use of FRP wrapping, steel caging or reinforce concrete jacketing for this purpose is now a common practice in many countries throughout the world. Even though a considerable number of researches have been conducted on retrofitting methods during past years, but very limited researches have been done to compare these methods. This research has investigated the effect of jacketing from different views. The... 

Even though a considerable amount of research has been conducted on composite wall system during past years, very limited research has been reported on shear walls strengthened by steel plates. In 2008, the composite shear wall, which consisted of reinforced concrete wall, retrofitted by steel plates, attached to both sides of RC walls using mechanical connectors in form of shear studs, bolts or lateral ties tested under axial load and lateral force. In this research, seismic behavior of RC shear walls strengthened by diagonal strips of steel plates is going to be studied. The result will be compared with RC shear wall which fully covered by steel plates.The behavior of RC shear wall will be... 

Even though a considerable amount of research has been conducted on composite wall system during past years, very limited research has been reported on shear walls strengthened by steel plates. In 2008, the composite shear wall, which consisted of reinforced concrete wall, retrofitted by steel plates, attached to both sides of RC walls using mechanical connectors in form of shear studs, bolts or lateral ties tested under axial load and lateral force. In this research, seismic behavior of RC shear walls strengthened by vertical strips of steel plates is going to be studied. The result will be compared with RC shear wall which fully covered by steel plates. The behavior of RC shear wall will... 

Composite Reinforced Concrete-Steel (RCS) frames which have reinforced concrete columns and steel beams attracted a lot of attention in recent years. They take advantage from the benefits of both reinforced concrete and steel frames thorough using the optimum combination of concrete and steel structural elements. In this research six structures including three 3-story, and three 6-story buildings are designed in a region with very high seismicity risk. These structures include composite RCS moment frames, special steel moment frames, and reinforced concrete special moment frames. RCS moment frames which are designed they not only have reinforced concrete columns similar to reinforced... 

In building construction, a rigid vertical diaphragm is capable of transferring lateral forces from exterior walls, roofs and floors to the ground foundation in a direction parallel to its planes.[1] Refractory elements against lateral forces contain moment frames, shear walls or a combination of them. In this research, shear walls are discussed. Nowadays, in cities having old contexture, some of the buildings should be destructed. Thus, modern buildings should be built. Due to the limitation of adequate space and lack of symmetrical plan, buildings must be built in asymmetrical form. To design the structures with asymmetrical plan, it is necessary to study buildings with presence of... 

The strengthening of reinforced concrete structures with externally bonded fibre reinforced polymer (FRP) laminates has shown excellent performance, so this technology is rapidly replacing externally bonded steel plates, steel or concrete jackets, and many traditional techniques available. In this study strengthening of reinforced concrete beams by GFRP to reduce creep deflection is investigated by mathematical method using available relations. Five RC beams with different dimensions, with and without strengthening with GFRP laminate, were investigated for their creep deflection. The creep coefficient of beams selected from experimental result that were mentioned in RILEM DATA BANK. In this... 

The structural behavior of deep beams is different with usual beams as a result of the low span-to-height ratio. Shear failure load is less for deep beams. Implementation of externally bonded reinforcement such as fiber reinforced polymers (FRP) is a unique method for shear strengthening of deep beams. In this study, the effects of FRP layers on the web of the reinforced concrete deep beam have been investigated by a nonlinear finite element program. Five beams four of which were strengthened with FRP laminates were numerically modeled and the results were compared with experimental results. The effect of some governing parameters such as compressive strength of concrete, orientation of...