Journal of Rehabilitation in Civil Engineering
Volume:6 Issue: 2, Summer Autumn 2018

This paper introduces a novel design concept for the development of efficient, sustainable Rocking-Wall Moment Frames (RWMFs) under seismic conditions. The proposed concepts lead to a novel structural configuration with provisions for Collapse Prevention (CP), Self-Centering (SC), reparability, performance control (PC), damage reduction, and energy based seismic analysis. It introduces the merits of design led analysis (DLA) over the traditional methods of approach, followed by the development of a lateral resisting system that is more efficient than its conventional counterparts. The fundamental idea behind the proposed methodology is that seismic structural response is mainly a function of design and construction, rather than numerical analysis. In design led analysis the rules of mechanics and structural design are induced rather than followed .The new system is a combination of grade beam restrained moment frames and articulated shear walls, tied to each other by means of post tensioned (PT) stabilizers and Gap Opening Link Beams (GOLBs).

In offshore structures, most of failures are caused by the lack of sufficient piles strength. Scour phenomena affects the load transition and the pile strength. The necessity of the consideration of scouring phenomena amplifies when the scour depth becomes remarkable, which can endanger the jacket stability. In this paper, a new method is used to consider the pile scouring using nonlinear pushover analysis with SACS software. A recently-built existing jacket platform namely SPD 19C is selected as a case study. Results show that Reserve Strength Ratio (RSR) of the jacket platform decreases when scour depth increased in the both aged and recently-built cases. RSR decreasing becomes more sensible as scour depth increases. According to API RP2A collapse will be occurred in the range of RSR

Buckling restrained braced frames (BRBFs) for seismic load resistance have been widely used in recent years. One of the key requirements for a buckling restrained brace is to sustain large plastic deformations under severe ground motions. The core of a buckling restrained brace is prone to fatigue fracture under cyclic loading. The earthquake induced fracture type of the core plate in a buckling restrained brace can be categorized as ultra-low cycle fatigue fracture. This paper investigates the ultra-low cycle fatigue fracture life of a type of composite buckling restrained brace previously tested. The newly developed cyclic void growth model was adopted to theoretically predict the fracture and crack initiation in the core. In addition, the Coffin-Manson fatigue damage model was applied to estimate the fracture life of the brace. A FEM model of the BRB developed in ABAQUS was used to evaluate the fatigue life. The analysis results showed that the cyclic void growth model is capable to nearly predict the fracture life of the core in buckling restrained brace.

Nowadays, the better performance of lightweight structures during earthquake has resulted in using lightweight concrete more than ever. However, determining the compressive strength of concrete used in these structures during their service through a none-destructive test is a popular and useful method. One of the main methods of non-destructive testing in the assessment of compressive strength of concrete in the service is ultrasonic pulse velocity test. The aim of this study is predicting the compressive strength of lightweight aggregate concrete by offering a suitable mathematical formulation. Many samples of lightweight aggregate concrete, made by expanded clay, have been produced and tested. After determining the actual compressive strength and indirect ultrasonic pulse velocity for each sample, a relationship was presented to predict the compressive strength through Gene Expression Programming (GEP). The results show the presented equation has high accuracy in estimating the compressive strength of samples and that experimental results are perfectly compatible with the test results.

In the present study, non-linear finite element analyses are carried out on the slender reinforced concrete columns wrapped using CFRP composite with different cross-sectional shapes having the same area. Thickness of the CFRP wraps, concrete compressive strength, corner radius, loading condition, slenderness ratio and column size are the main parameters of this study. According to this, four different eccentricity-to-section-height ratios, four different levels of the CFRP thicknesses in the strengthened specimens, the slenderness ratio of the length to the section-height (l/h) from 6 to 12, three various types of column size, concrete compressive strength values from 20 MPa to 50 MPa and corner radius from 10 to 40 mm are considered. This paper presents a comparison of a numerical simulation using ABAQUS software, with the results of experimental tests by previous researchers to validate finite element models. It is shown that the predicted results by this numerical study are in reasonable agreement with the results of experimental studies. The results of this investigation also represented a considerable enhancement on the performance of strengthened columns with CFRP compared to unstrengthened columns.

This paper aims to study the influence of soil-structure interaction on plastic energy demand spectra directly derived from the energy-balance equations of soil-shallow-foundation structure with respect to an ensemble of far-field strong ground motions obtained from Pacific Earthquake Engineering Research (PEER) database and recorded on alluvium soil. The superstructure is modeled as a single-degree-of-freedom (SDOF) oscillator with Modified Clough stiffness degrading model resting on flexible soil. The soil beneath the superstructure is considered as a homogeneous elastic half space and is modeled through the concept of Cone shallow foundation Models. A parametric study is carried out for 2400 soil-structure systems with various aspect ratios of the building as well as non-dimensional frequency as a representative of the structure-to-soil stiffness ratio having a wide range of fundamental fixed-base period and target ductility demand values under a family of 19 earthquake ground motions. Results show that generally for the structure located on softer soils severe dissipated energy drop will be observed with respect to the corresponding fixed-base system. The only exception is for the case of short period slender buildings in which the hysteretic energy demand of soil-structure systems could be up to 70% larger than that of their fixed-base counterparts. Moreover, dissipated energy spectra are much more sensitive to the variation of target ductility especially for the case of drastic SSI effect.

The wind’s effectiveness was compared in different points of a watershed using a quantity called The Wind Shelter Index.The wind’s effectiveness was compared in different points of a watershed using a quantity called The Wind Shelter Index. It is necessary to choose a distance called the effective distance in the process of this index determination. The criterion already used for this purpose was only usable in snowy places. According to the wind shelter index usability in some phenomena that are not in snowy areas, the use of this index will be applied. This study uses observational data of snow surveys from 258 points in Samsami Basin to introduce a new index called “Virtual Wind Shelter” that can be used to choose the effective distance of the area applicable in snowy and non-snowy places. The results showed that the index introduced in this study has the capability of replacement with the correlation of wind shelter index with snow depth criterion.

Using 100% of recyclable materials in  road construction, protecting the environment, is an influential factor  in the decision-making process for road projects. As one of the most  important elements in nature and an original basis for the formation of  life on earth, Carbon has been used in many different industries for its high surface area and porosity. Because of asphalt binder rheology  characteristics, asphalt layers tend to return to their initial  conditions after traffic flow but some of these deformations return in  elastic form and some not return in plastic form. In this research, the Dynamic Shear Rheometer (DSR) test was used to analyze asphalt Binder  performance Grade. Carbon Black particles processed from agricultural  waste recycling (walnut skin) with specific weight percentages of 3, 5, 7 and 10, were used for asphalt binder rehabilitation. According to the  results, the use of Carbon Black particles derived from the recycling of agricultural waste improves asphalt binder performance Grade from PG64  to PG74 for modified asphalt binder with 7% carbon black and rheological parameters like complex modulus increased 1.7 times and phase angle  decreased approximately 0.85 times.

Today, for the moment frame structures, seismic provisions of the structural engineering design codes depend on the inelastic deformation as well as inelastic capacity of the  connections. A cyclic loading protocol is normally exercised for  measuring such capability. This paper investigates the deformation  capacity of steel moment resisting frame’s connections subjected to different loading protocols. To evaluate the performance of the  connections subjected to various cyclic loads, behavior of three types  of connections is studied. Behavior and capacity of each connection are assessed subjected to different loading protocols; namely ATC, FEMA and  SAC. The results from this research indicate that the ATC and FEMA  loading make greater demands on the connections; while SAC basic loading shows a better agreement with the target values of the loading  protocol. A loading protocol has been developed taking some criteria  into account in order to match the target values presented in SAC study  for steel moment connection’s bam to column sub-assemblies. Then the  connections were subjected once again to the proposed loading protocol  and results compared to those of other loading protocols. The results reveal that the connections subjected to the proposed loading protocol  provide greater deformation and strength capacity. Also, lower  equivalent plastic strain and lower dissipated energy were observed when the connection is subjected to the proposed loading protocol.

A hydraulic jump phenomenon serves a  variety of purposes, for instance, to dissipate the energy of flow to  prevent bed erosion and aerate water or to facilitate the mixing process of chemicals used for the purification of water. In the current study,  three artificial intelligence approaches, namely artificial neural  networks (ANNs), two different adaptive-neuro-fuzzy inference system  with grid partition (ANFIS-GP), and gene expression programming (GEP)  were applied to forecast developed and non-developed hydraulic jump  length. Four different GEP, ANFIS-GP and ANN models comprising various  combinations of Froude number, bed roughness height, upstream and  downstream flow depth based on measured experimental data-set were  developed to forecast hydraulic jump length variations. The  determination coefficient (R2) and root mean square error (RMSE)  statistics were used for evaluating the accuracy of models. Based on the comparisons, it was found that the ANN, ANFIS-GP and GEP models could be employed successfully in forecasting hydraulic jump length. A  comparison was made between these artificial intelligence approaches  which emphasized the superiority of ANNs and ANFIS-GP over the other intelligent models for modeling developed and non-developed hydraulic  jump length, respectively. For non-developed hydraulic jump, the R2 and RMSE values obtained as 0.87 and 2.84 for ANFIS-GP model.

Nowadays, the better performance of lightweight structures during earthquake has resulted in using lightweight concrete more than ever. However, determining the compressive strength of concrete used in these structures during their service through a none-destructive test is a popular and useful method. One of the most original approach of non-destructive testing to obtain of compressive strength of concrete used in structures is ultrasonic pulse velocity test. The purpose of this research is predicting the compressive strength of LWA concrete by proposing an accurate mathematical formulation. Many samples of lightweight aggregate concrete, made by expanded clay, have been produced and tested. After determining the actual compressive strength and indirect ultrasonic pulse velocity for each sample, a relationship was derived to estimate the compressive strength through Gene Expression Programming (GEP). The results show the presented equation shows high accuracy in predicting the compressive strength of LWA and the estimated outcomes have a considerable compatibility with actual samples.