ASIAN JOURNAL OF CIVIL ENGINEERING (BUILDING AND HOUSING)
Year:2016 | Volume:17 | Issue:7|Papers Count:9

Early 1970s, the steel shear walls in buildings were used as resistant systems against lateral loads. However, their weakness on the fast buckling of the web plate forces the designer to use reinforced concrete layer at one or both sides of the steel shear walls. The resultant system, composite steel plate shear walls, are then utilized as efficient systems against lateral loads. In this paper, we investigated the position and dimensions of the rectangular opening on the seismic performance of this complex system. To fulfill this aim, some models with different opening surface and their location were considered and subjected to cyclic loads and then analyzed using a finite element method. The results show that by increasing the size of the center opening surface the seismic characteristics will reduce.

In an attempt to reduce the cost of concrete production, efforts are being made to utilize part of the waste generated during rice production. This research work investigates the effects of partially replacing sand with rice husk on the structural properties of fresh and hardened concrete. Laboratory tests to determine the workability, air content, compressive strength and water absorption properties of the concrete, with varying proportion of rice husk as partial replacement of the fine aggregate, were conducted. The workability of the concrete was improved as its rice husk content increased. The unit weight and compressive strength of the concrete decreased with increasing rice husk content while the concrete specimens absorbed more water and have increased air content with increasing rice husk content. The use of not more than 12.5% rice husk, as replacement of sand, was recommended for producing concrete that will be used for load-bearing applications.

The efficiency of a seismic retrofit using externally bonded fiber-reinforced polymer composites on existing damaged reinforced concrete joints, designed prior to the introduction of modern standard seismic design code provisions in the mid-1970s, are herein presented, based on experimental investigations on beam-column joint subassemblies. The experimental program comprises 8 external beam–column joint connection subassemblages tested in 2 phases, the first phase was the damaging phase and the second was aimed to the repairing the damaged joints. The joints had no beam-column joint transverse reinforcement and special stirrups in beam and column critical lengths. These Non-Seismically designed (NS) joints were damaged with different levels at the first phase of the experiment. In the second phase, the damaged joints were strengthened with externally bonded carbon-fibre-reinforced plastics (C-FRP) sheets. From the observed responses the load carring capacity and stiffness of the pre-damaged strengthened joints were improved in moderate initial damages (less than 1.5% drift ratio). Also, the use of CFRP sheets increased the capacity of energy dissipation of the rehabilitated beam–column specimens in comparison to as-built specimen. It can be deduced that the technique of externally bonded retrofitting (EBR) using C-FRP sheets is efficient in moderately pre-damaged joints, i.e. the damage levels less than 1.5% drift ratio. This level is named as the repaire-ability level by using EBR strengthening method.

Optimum design of structures utilizing metaheuristic algorithms can highly be time consuming when applied to real-world problems. This paper aims to introduce an evolutionary heuristic method for optimization of skeletal structures that requires less computational time while preserving the solution accuracy. Enhanced colliding bodies optimization as a simple and efficient method for structural optimization is integrated with the upper bound strategy to reduce the total number of structural analyses. Truss and frame structures are considered as benchmarks and constraints are imposed according to the provisions of ASD-AISC and LRFD-AISC specifications. The new hybrid metaheuristic algorithm which is called UECBO has a simple structure and is capable of performing suitable optimal design. The proposed method is tested and compared by means of several examples previously reported in literature.

This paper presents a novel scheme for large deformation analysis of space truss structures, including both geometric and material nonlinearities, using a predictor-corrector procedure, titled as fixed incremental displacement (FID) method. The nonlinear equilibrium equations are solved using an incremental-iterative method based on the displacement control scheme, as, by employing a specified displacement, the corresponding load will be obtained. In the present method, the ratio of the size of increment displacement vector to that of total displacement is assumed to be constant at the beginning of each increment. The geometric nonlinearity is considered based on an updated Lagrangian formulation, while the material nonlinearity is accounted for by tracing a complete stress-strain relationship. A computer program based on the algorithm is developed for analysis of space structures with complex behaviors, including snap-through buckling, snap-back, unloading and inelastic postbuckling analysis. This algorithm can accurately trace the equilibrium path of nonlinear problems. To demonstrate the efficiency and accuracy of the method developed here, some well-known trusses are investigated and analyzed using the aforementioned algorithm and the results are compared with those of cylindrical arc-length method.

Roller-compact concrete pavement (RCCP) is known as a good alternative material for common asphalt pavements. They have more durability against environmental conditions. Common asphalts could be more deformable than RCCPs. It had greater capacity for energy dissipation and material toughness in comparison of RCCP. According to previous theories adding some pieces of recycled crumb tires could improve the quality of final product and made RCCPs more deformable and durable. In this paper the behavior of rubberized RCCPs were studied by different conditions. The experimental program was defined in order to study the relation of crumb-tire replacement percentage vs. some hardened concrete parameters like average modulus of elasticity, Poisson’s Ratio, Tensile & Compressive strength, water absorption and durability against the thermal conditions. Results of experiments proved that different behaviors could be recorded by different amounts of rubber replacement percentage.

In this study, a fuzzy logic controller is employed to synchronize the response of two adjacent buildings coupled with a magneto-rheological (MR) damper and also, to reduce the minimum separation gap required, thus avoiding pounding hazard between adjacent buildings. Adopting a coupling strategy allows us to transform two separated structures into one system coupled by a damping device, which results in a synchronised vibrating mode between the coupled structures. A number of structural configurations presenting a high pounding risk are investigated for this study. It has been found that chances of pounding are reduced along with a reduction regarding top floor displacement and maximum drift. The use of fuzzy logic controller results in optimization of the damper force. In addition, it has been also observed that the use of a single damper at the top floor reduces responses and avoids pounding of adjacent buildings.

Industrial storage racks are among the most important structures made from cold-formed steel sections. This paper deals with linear and nonlinear stability analysis of a pallet racking system. The main focus of this study is to ascertain the stability of 2-D frames of a pallet racking system. With this objective, pallet racking system with cold-formed steel section is simulated by 2-D models using shell elements in ABAQUS. Linear and nonlinear stability analyses are carried out on these frames. The results are obtained from FE analysis of frames with 12 types of column sections are presented in this paper.

A cold-formed steel section is more sensitive to local buckling than typical hot rolled sections. It is characterized by light weight, high strength, economical, wide variety, smooth surface and accurate size. The web panels are used as stiffened plates that can receive both high shear and high moment in different sections or in the same section depending on the beam statical system. One of the methods of reducing the web thickness is the use of corrugated sheets as webs. However, they are suggestible to various modes of buckling including local and distortional buckling. The main aim of this thesis is to find the maximum load carrying capacity of the specimen and possible modes of failure under two point loading at the corrugated web in cold formed sections with varying thickness. Steel I section with the corrugated web having two flanges are welded with the web. The length of the specimen is kept constant for 1200mm and the thickness is varied from 0.7mm, 0.9mm, and 1.2mm.The results for a simply supported beam is subjected to a two point loading are examined. Finally, numerical analysis using ANSYS 15.1 results are analysed and justified with experimental results for an explanation.