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An attempt has been made to explore the general trends in the seismic response of planasymmetric structures when subjected to near-fault and far-fault ground motions. Systems with structural wall elements in both orthogonal directions considering actual and common nonlinear behavior under bi-directional excitation were studied. Idealized single-storey models with uni-axial eccentricity were employed. The main findings are: The rotational response trend considering actual behavior method would be different from common behavior method assumption, when the system subjected to near-fault motions. In the former case, the minimum rotational response could be achieved, when stiffness and strength centers are located on opposite side of the mass center. In the latter case, stiffness eccentricity determines the minimum and maximum rotational response. General trends in the rotational demand for far-fault motions, considering two type behavior assumptions, are similar to the last case. Moreover, in near-fault motions, when stiffness and strength centers are located on opposite side of the mass center, stiff side displacement demand would be greater than that soft side which is contrary to the conventional guidelines. While, in farfault motions similar to near-fault motions which stiffness and strength centers are located on one side of the mass center, displacement demand would be according to conventional guidelines.

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 Puducherry is a coastal region in India where the growth of Ulva fasciata (Delile) is very abundant on all marine structures. Though the detrimental effect of this macro algae Ulva fasciata is a secondary one, its effect has to ascertain. To know its effect, the basic mechanism by which Ulva fasciata deteriorates concrete structures, M20 grade concrete cubes were casted and kept in the coastal area where there is abundant growth of Ulva fasciata and also laboratory simulation has been carried out. To ascertain the detrimental effect by the macro algae on concrete surface, samples were collected from the concrete cubes kept in the coastal area and also from the laboratory simulated one. The collected samples were analyzed by SEM, EDX and XRD to establish the degree of deterioration done by marine algae on concrete surface. The SEM and EDX results showed that there is a remarkable change in the base materials viz., Ca and Si content and XRD results revealed the absence of Calcium Hydroxide. Both the results confirmed the biodeterioration of concrete by the marine green algae.

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Endurance Time (ET) method is a response history based analysis procedure that can be used for estimating the seismic response

of structures at different excitation levels in each response history. This seismic analysis method utilizes specific intensifying

acceleration functions to analyze seismic behaviors. One of the potential applications of the ET method is in the seismic

assessment of shell structures. In this study, a procedure for linear seismic analysis of shell structures is proposed and

applications of this method is investigated for several cases of shell structures. These structures are analyzed under three ET

acceleration functions in one direction and the results are compared to time history analysis considering seven actual earthquake

records. Moreover, the results of the ET method are compared to response spectrum analysis method. The outcomes of the study

reveal that the ET method predicts the linear seismic performance of shell structures with acceptable precision and significant

reduction in analysis time. Furthermore, it is conluded that scattering of results of three ET analysis is very low and one analysis

can be used instead of three. Finally, the comparison between THA and RSM results verify that response spectuarm method is a

conservative method which occasionally encounters problems to evaluate bending stresses of shell structures

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It has been pointed out the static lateral response procedure for a base-isolated structure proposed in International Building Code (IBC) somewhat overestimates the seismic story force. That is why in the current paper, vertical distribution of base shear over the height of isolated structures considering higher mode effects under near field earthquakes is investigated. Nonlinear behavior of isolation systems cause variation of frequencies transmitted to the superstructure and consequently higher modes effects should be considered. In this study base shear distribution obtained from nonlinear dynamic analysis is compared with that achieved from IBC for assessment of the international building code. This investigation has been conducted in two parts, in order to have an appropriate base shear distribution formula for isolated structures under near field earthquakes. In the first part using three first mode shapes of isolated structure and introducing coefficient corresponding to each mode, extracted from nonlinear dynamic analysis under near field earthquakes, a new formula has been derived. In the second part, the mode shape coefficients have been obtained theoretically and consequently a new base shear distribution over the height of isolated structures including the isolation system properties under near field ground motions was proposed.

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New advances in geomatics and communications technologies are enabling the development of Automated Auscultation System for structure monitoring. In particular, Differential GPS (DGPS) technique allows real-time monitoring of structures with millimetre accuracy after an appropriate mathematical treatment. The results of real-time DGPS monitoring of a pilot dam over 15 months are presented and compared with the results of pendulums and angular collimation. DGPS monitoring was established to control two points at the top of the dam with reference to an external and stable station. Communications were critical, evolving from initial GPRS connections to more reliable ASDL line in the last months. Real-time DGPS positions were filtered to reach millimetric accuracy through Kalman filter. Two configurations of the filter were tested, one more adapted to predictable and uniform velocity deformations (low frequency) and another more suitable for sudden and large movements (high frequency). Root mean square errors were calculated taking pendulums as a reference. Results show that both DGPS and angular collimation allow monitoring with millimetric accuracy. In the last period, where communications with processing server were stable, a global accuracy of 1.44 and 1.86 mm was reached for real-time DGPS monitoring. RINEX post-processing yielded millimetric results, validating real-time observations. We can affirm that the DGPS system is very useful for dam auscultation and safety as it detects adequately absolute deformations, being a complement to existing methods which should be considered in new safety plans.

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For the analysis of structures, the first step consists of configuration processing followed by data generation. This step is the most time consuming part of the analysis for large-scale structures. In this paper new graph products called triangular and circular graph products are developed for the formation of the space structures. The graph products are extensively used in graph theory and combinatorial optimization, however, the triangular and circular products defined in this paper are more suitable for the formation of practical space structural models which can not be generated easily by the previous products. The new products are employed for the configuration processing of space structures that are of triangular or a combination of triangular and rectangular shapes, and also in circular shapes as domes and some other space structural models. Cut out products are other new types of graph products which are defined to eliminate all of the connected elements to the considered node to configure the model or grid with some vacant panels inside of the model. The application of the presented graph products can be extended to the formation of finite element models.

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In this paper, a new enhanced version of the Particle Swarm Optimization (PSO) is presented. An important modification is made by adding probabilistic functions into PSO, and it is named Probabilistic Particle Swarm Optimization (PPSO). Since the variation of the velocity of particles in PSO constitutes its search engine, it should provide two phases of optimization process which are: exploration and exploitation. However, this aim is unachievable due to the lack of balanced particles’ velocity formula in the PSO. The main feature presented in the study is the introduction of a probabilistic scheme for updating the velocity of each particle. The Probabilistic Particle Swarm Optimization (PPSO) formulation thus developed allows us to find the best sequence of the exploration and exploitation phases entailed by the optimization search process. The validity of the present approach is demonstrated by solving three classical sizing optimization problems of spatial truss structures.

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The increase in the computational capabilities in the last decade has allowed numerical models to be widely used in the analysis, leading to a higher complexity in structural engineering. This is why simple models are nowadays essential because they provide easy and accessible understanding of fundamental aspects of the structural response. Accordingly, this article aims at showing the utility and effectiveness of a simple method (i.e. the Load Path Method) in the interpretation of the behaviour of masonry buildings subjected to foundation settlements due to landslide. Models useful for understanding brick-mortar interface behaviour as well as the global one are reported. The global proposed approach is also validated by using Bi-directional Evolutionary Structural Optimization method. Moreover, drawing inspiration from a case study, the article shows that the proposed approach is useful for the diagnosis of crack patterns of masonry structures subjected to landslide movements.

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An analytical nonlinear stress-strain model and a microscopic damage index for confined and unconfined concretes together with a macroscopic damage index for reinforced concrete (RC) structures under cyclic loading are proposed. In order to eliminate the problem of scale effect, an adjustable finite element computer program was generated to simulate RC structures subjected to cyclic loading. By comparing the simulated and experimental results of tests on the full-scale structural members and concrete cylindrical samples, the proposed stress-strain model for confined and unconfined concretes under cyclic loading was accordingly modified and then validated. The proposed model has a strong mathematical structure and can readily be adapted to achieve a higher degree of precision by modifying the relevant coefficients based on more precise tests. To apply the proposed damage indices at the microscopic and macroscopic levels, respectively, stress-strain data of finite elements (confined and unconfined concrete elements) and moment-curvature data of critical section are employed. The proposed microscopic damage index can easily be calculated by using the proposed simple analytic nonlinear stress-strain model for confined and unconfined concretes. The proposed macroscopic damage index is based on the evaluation of nonlinear local degradation of materials and taking into account the pseudo-plastic hinge produced in the critical section of the structural element. One of the advantages of the macroscopic damage index is that the moment-curvature data of the critical section is sufficient in itself and there is no need to obtain the force-displacement data of the structural member.

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The interactive effects of adjacent buildings on their seismic performance are not frequently considered in seismic design. The adjacent buildings, however, are interrelated through the soil during seismic ground motions. The seismic energy is redistributed in the neighboring buildings through multiple structure-soil-structure interactions (SSSI). For example, in an area congested with many nearby tall and/or heavy buildings, accounting for the proximity effects of the adjacent buildings is very important. To solve the problem of SSSI successfully, researchers indicate two main research areas where need the most attention: 1) accounting for soil nonlinearity in an efficient way, and 2) spatial analysis of full 3D soil-structure models. In the present study, three-dimensional finite element models of tall buildings on different flexible foundation soils are used to evaluate the extent of cross interaction of adjacent buildings. Soil nonlinearity under cyclic loading is accounted for by Equivalent Linear Method (ELM) as to conduct large parametric studies in the field of seismic soil-structure interaction, the application of ELM is preferred over other alternatives (such as application of complicated constitutive soil models) due to the efficiency and reliability of its results. 15 and 30 story steel structures with pile foundations on two sandy and clayey sites are designed according to modern codes and then subjected to several actual earthquake records scaled to represent the seismicity of the building sites. Results show the cross interaction of adjacent buildings on flexible soils, depending on their proximity, increases dynamic displacements of buildings and reduces their base shears. 

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The paper presents a parametric numerical study on the horizontal load-bearing capacitiy of timber framed wall elements coated with single fibre plaster boards (FPB) that can be used in the construction of single- or multi-storey prefabricated buildings. The research deals with both the full elements (without any opening) and with elements containing an opening. The key behaviour indicators like the racking stiffness and strength were determined and presented as ratios dependent on the opening area. A comparative study has proved that none of the methods from the literature that were previously developed for different types of wall elements can be accurately applied to the FPB-sheated panels. It has also been shown that the methods currently available in the European design codes underestimate the capacity of wall elements with openings. Based on the results some diagrams are proposed that enable quick and efficient determination of the essential properties of wall elements with arbitrary areas of openings and may thus represent a useful tool for the structural design process.

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Observations and investigations have proved that using traditional fire curves such as stand-ard fire curves and natural fire curves should be limited to small/medium compartments. In addition, when using the traditional fire curves, a uniform temperature is assumed throughout the compartment. However, for large open compartments, assuming uniform temperature is not compatible with real fires. To overcome this limitation, a non-uniform fire method named as travelling fire is employed as an alternative. A study is performed here on a seismic-damaged large plan 3-story reinforced concrete structure designed to meet the life safety level of performance when exposed to a travelling fire. To draw a comparison, the structural fire analysis is also performed using the traditional methods. The results show a notable difference – while the fire resistance based on the travelling fire is around 91 minutes, it is around 140 minutes when based on a uniform temperature. This shows that the structure studied is more susceptible to failure when subjected to the non-uniform fire than the uniform fire.

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Engineering design usually requires considering multiple variances in a design and integrating them appropriately in order to achieve the most desirable alternative. This consideration takes particular importance in the constructional projects of civil engineering. However, frequently, the structural designer’s considerations in civil engineering teams contrast the stylish and creative novelties of architectures. Then, we should take up new methodologies to yield appropriate alternatives which meet artistic aspects of design and simultaneously satisfy the structural designer’s demands. Consequently, the process of design should incorporate the multi-fold aspects of engineer’s requirements and their personal preference. So, in this study, we preset a systematic approach, so-called desirability based design, to perform a directed multi-objective optimal design considering various aspects of a design, based on soft-computing methods. Fuzzy logic integrated with genetic algorithm is employed to build a decision-making fuzzy system based on expert knowledge. It will be employed to conduct the designing process. Illustrative examples show practicality and efficiency of the presented methodology in structural design of several space structures.

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In this study, the effects of high temperatures on the mechanical and microstructural properties of high strength concretes (HSCs) made with metakaolin (MK) are investigated. For this purpose, the concrete mixtures made with MK were produced with water-binder ratio of 0.2. The mechanical properties of these concretes at 25, 250, 500 and 750 oC temperatures were determined. Besides, the effect of high temperature on the microstructural changes of cementitious matrix, interfaces between aggregate particles-cementitious materials and aggregates of these concretes were inspected by X-ray diffraction, scanning electron microscope and plane polarized transmitted light (PPTL) analyses. The results indicate that the ultrasound pulse velocity, compressive strength, flexural strength and splitting tensile strength values of these concretes decrease especially depending on the increase of the high temperature after 250 oC. The heated concrete specimens were also examined at both macro and micro scales to determine the discoloration, alteration and cracks of HSC at different temperatures. PPTL analyses show that increasing temperature cause impairing of interfaces between aggregate particles and cementitious materials. The results also show that the partial replacement of MK with cement has the best performance on the mechanical properties of HSC.

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This paper describes both global and local versions of an energetic analytical model to quantify the damage caused to reinforced concrete (RC) structures under monotonic, cyclic or fatigue loading. The proposed model closely represents the damage to structures and yields a damage index (DI) for the RC members. The model is cumulative and is based on the energy absorbed. The energy under the monotonic envelope curve at the failure of the member is taken as a reference capacity. The data required to apply the model in any given situation or member can be obtained either by numerical simulation or from experimental tests. An analytical computer program was developed to simulate numerically the response of RC members taking into account the nonlinear behavior of the materials and structures involved. The proposed model was verified by comparison with practical tests undertaken by other researchers on over 20 RC columns. The comparison demonstrates that the model provides a realistic estimation of the damage of the RC structural members. The comparison between values of the proposed DI calculated based on experimental test data and numerical simulation results for a cyclic loading case shows that to calculate DI, it is not necessary to perform expensive experimental tests and that using a nonlinear structural analytical simulation is sufficient. The results are also compared to a damage model proposed by Meyer (1988).

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This study presents methods for numerical modelling and the static computer analysis of steel decks fixed on scaffoldings. The main problem raised here is the method of creating models of a single deck and determination of the accuracy of every model for various design situations: the analysis of state stress in components of decks, the strength analysis of scaffolding where decks can be loaded by untypical the arrangement of materials and the strength analysis of full scaffoldings. The analysis of a state stress in components of a deck requires a detailed model. The analyses of scaffoldings with load by materials have to be performed with using more simple models of platforms. The static-strength analysis of full scaffoldings with many frame elements can be performed if the simplest models of decks are used. In this paper the sets of truss elements replace the stiffness of scaffolding decks.