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As a matter of fact, structural drift is a random variable that is associated with several bases of the uncertainties related to the loading excitation and structural resistance. Hence, it seems essential to utilize the probabilistic philosophy to provide a design criterion of control the structural drift. The current study was conducted to propose a probabilistic approach to control the structural drift subjected to seismic loading. The main contribution of this manuscript is to propose a new sophisticated design criterion to control the structural drift using the reliability analysis. As-a-state-of-the-art, a new limit state function is established to be utilized for reliability analysis of the considered extreme event. To do so, several different steel frames are analyzed and investigated using the existing design criterion of the ASCE07 code. Also, the analysis of the critical excitations is conducted to deliberate the required target reliability indices for the considered limit state function. Accordingly, the reliability index spectrum is illustrated which revealed that the drift of the structures is related to the fundamental structural period. Eventually, based on the consistency of the reliability index consideration a stylish formula is proposed to control the drift reliability index corresponding to the target reliability indices constraints in the range of 2 to 4 (2 ≤ β ≤ 4). In addition to the main advantage of the proposed design criterion which is to provide a consistent range of the reliability level for different structures. Indeed, the analysis of the critical excitation shows that the reliability index spectrum varies by the fundamental frequency of the structure. Hence, in this research, a new structural drift criterion was proposed to sophisticatedly present the design criterion based on the fundamental structural period. Also, the proposed design criterion contains the deflection amplification factor to conclude the comprehensive inter-story drift control. [ABSTRACT FROM AUTHOR]

The purpose of this study is to examine the influence of additives on estimating the useful service life of self-compacting concrete (SCC). For that, durability tests were performed on 43 SCC mix designs to estimating the service life of SCC based on the FIB model. The investigated supplementary materials included xanthan gum at concentrations of 0.2% and 0.25% by weight of cement, microsilica at concentrations of 5%, 7% and 10% by weight of cement, and nanosilica at concentrations of 2%, 3% and 4% by weight of cement. All 43 designs met the reliability index of the model, thereby obtaining the estimated service life for each design. The findings revealed that in chloride-rich environments, the control sample exhibited greater penetration depth compared to the concretes incorporating xanthan gum, microsilica and nanosilica additives. This observation suggests that the inclusion of xanthan gum extends the service life of SCC due to the formation of a denser and more cohesive structure in the hydration products of xanthan gum-modified concrete. Additionally, the investigations conducted indicate that the presence of nano and micro additives effectively reduces voids, while xanthan gum plays a significant role in minimising cracking and enhancing the thickening properties of the concrete. [ABSTRACT FROM AUTHOR]

Abstract Medial Tibial Stress Syndrome MTSS is frequently diagnosed as a severe clinical issue which occurs due to the cycle loadings (fatigue failure). Since the mechanical properties of the bones are random variables, therefore, there is a need for a probabilistic approach to rationally assess the reliability level of the fatigue failure of the tibia. The main contribution of this paper is to introduce a novel limit state function to determine the fatigue damage state and the reliability index of MTSS based on the different loading and aging conditions. In this study, the tibias of the several people at the different ages are subjected to the fatigue loadings. The load carrying capacities of the considered specimen are determined based on the reliability analysis. Indeed, several 3D finite element analyses are performed to find out the damage states of the tibias. Accordingly, the reliability-based stress analysis is accomplished to localize the most vulnerable zone of the bone. As it was expected, the higher loading cycles associated with the elder bones is related to the lowest fatigue reliability level. Finally, the target reliability level of MTSS is proposed to deliberate the safe level of the loading condition on the tibia in terms of the walking distance. [ABSTRACT FROM AUTHOR]

The target reliability is a design constraint that assures the required safety level for structures. Derivation of the target reliability is a complicated and challenging task. To determine the target reliability, two main approaches can be considered. The first approach is based on engineering judgment with respect to past observations of structural failure, while the second method is based on optimization theory. In the past, structural design codes implicitly assumed the target reliability with regard to past experiences, however, the objective of the optimization approach is to compute the target reliability using minimization of the cost-failure function. This contribution attempts to establish an optimization procedure to determine the target reliability for structures with consideration of the construction cost, failure cost, maintenance cost, structural life-time, discount rate, time-dependency of the load and resistance, and structural importance factor. Accordingly, the relationship between, target reliability, structural cost, structural importance factor, and structural life-time are depicted using the contour concept. Eventually, the target reliability for steel girder bridges is determined concerning the ultimate limit state. [ABSTRACT FROM AUTHOR]

Stipulating a space headway is a pivotal concern in traffic engineering. Although consideration of a larger headway leads to safer traffic movement, consideration for a smaller headway can serve more traffic volume, which is significant from an economic standpoint. Implementation of a smaller headway, however, could lead to the tailgating phenomenon (short distances between two vehicles), which is perceived as troublesome and dangerous. Evaluating the space headway provides a reasonable approach to understanding the operational benefit for safety and traffic concerns. Using probabilistic analysis to account for uncertainty can be one of the best applicable methods because the headway data are not deterministic and are treated as random variables. More specifically, by emphasizing the reliability analysis, it is feasible to determine the appropriate space headway. The objective of this paper is to present a state-of-the-art approach for the evaluation of the statistical parameters of the headway by utilizing the reliability analysis. Several data sets among entire states were obtained from the Federal Highway Administration (FHWA) in 2012 and utilized in an analysis of a more pragmatic approach. [ABSTRACT FROM AUTHOR]

• In this study, a new method is proposed to calculate the target reliability index of the bridge's piers associated with the extreme limit state function concerning seismic design criteria. • As a-state-of the-art, the reliability index of bridge pier is stipulated using a new generation of the limit state function corresponding to the interaction. • The objective function of the target reliability is updated to explicitly compromise the uncertainties of the seismic using the probabilistic seismic hazard analysis. • The contour concept is provided to determine the target reliability analysis of the concrete bridge pier subjected to the earthquake extreme events. Target reliability is an essential design constrain for probabilistic-based design approaches. The target reliability analysis requires a double optimization process concerning the trade-off between safety and cost. In this study, a new method is proposed to calculate the target reliability index of the bridge's piers associated with the extreme limit state function concerning seismic design criteria. First, as a-state-of the-art, the reliability index of bridge pier is stipulated using a new generation of the limit state function corresponding to the interaction failure mode. In doing so, a sophisticated reliability assessment is introduced to compute the reliability level of the pier subjected to the flexural and axial failure modes using a probabilistic interaction surface. In an attempt to capture more sustainable target reliability, an optimization approach is emphasized to minimize the structural cost function at a different structural lifetime. In addition, the objective function of the target reliability is updated to explicitly compromise the uncertainties of the seismic using the probabilistic seismic hazard analysis while the structural resistance probability model is driven using the Monte Carlo simulation. It should be noted that the structural maintenance and structural failure cost are modeled using the relationship between the initial cost and economic inflation rate corresponding to the expected lifetime. Subsequently, the contour concept is provided to determine the target reliability analysis of the concrete bridge pier subjected to the earthquake extreme events. [ABSTRACT FROM AUTHOR]

• A reliability-intensity surface is proposed to represent the post-earthquake reliability indices of a bridge. • The post-earthquake reliability index of a bridge is linked to the resulting traffic flow capacity. • A reliability-based indicator is proposed to assess the expected post-earthquake traffic flow capacity of a bridge. • The proposed indicator can complement qualitative post-earthquake bridge inspection and evaluation. Bridges are one of the most critical but vulnerable components in a transportation network during an earthquake event. Due to structural damage, the post-earthquake safety of bridges can be reduced significantly, and in order to maintain their safety, the allowable traffic flows of bridges are often controlled or regulated. Since the post-earthquake traffic flow capacities of bridges play an integral role in assessing the flow capacity of a transportation network and subsequently evaluating the resulting disruptions to supply chain systems as well as the movement of people and vehicles, it is imperative to understand the expected post-earthquake functionalities of bridges as part of the transportation network. This paper proposes a reliability-based indicator for assessing the expected post-earthquake traffic flow capacity of a highway bridge. In this paper, the structural safety of a bridge before and after an earthquake event is expressed by its reliability index. In order to simplify the process of computing the post-earthquake reliability indices of a bridge associated with a wide range of earthquake intensities, a bridge-specific reliability-intensity surface is introduced to represent the reliability indices given a set of earthquake intensities and the associated uncertainties. Then, the post-earthquake reliability index of a bridge is linked to the resulting traffic flow capacity by adjusting the nominal values of the live load based on the post-earthquake remaining traffic flow capacity. Using the reliability-intensity surface and the relationship between reliability index and traffic flow capacity, the allowable traffic flow capacity of a bridge subjected to a given earthquake intensity is computed, and by considering a range of earthquake intensities to which a bridge is potentially exposed, the proposed indicator represents the average allowable traffic flow that can be carried by a bridge in the event of an earthquake. [ABSTRACT FROM AUTHOR]

Liquid storage tanks play a significant role in storing hazardous liquids in process industries. Hence, their proper seismic performance is considerably important to prevent the catastrophic consequences of tank failure. This study focuses on seismic safety assessment of oil storage tanks. To this end, four unanchored tanks of various height-to-diameter ratios (H/D) were considered and their elastic and inelastic buckling failures were studied, as well as their uplifting behaviour. To this end, incremental dynamic analysis was employed in an Abaqus platform using the lateral seismic excitations. Different patterns of random geometric imperfections of various amplitudes were considered in the tank models. The Budiansky–Roth procedure was followed to calculate the buckling capacities of tank shells. The results of this study revealed that the imperfection has a small but notable effect on buckling capacity of tank shells, but its effect on tank uplift is negligible. [ABSTRACT FROM AUTHOR]

• Most of pushover methods are used for estimating the seismic demands of buildings. • Multi-mode Adaptive Displacement-based Pushover (MADP) analysis procedure is proposed. • MADP is developed for estimating the seismic demands of RC moment-resisting frames. • Case study of RC frames under different ground motion intensities is conducted. • Results of MADP are in good agreement with those of nonlinear response history analysis. The main contribution of this paper is to develop a new multi-mode adaptive pushover analysis procedure for estimating the seismic demands of RC moment-resisting frames. The proposed procedure enhances the seismic demands of conventional pushover analysis methods by combining the advantages of 'multi-modal' and 'adaptive' pushover procedures. The presented method, which has been named the multi-mode adaptive displacement-based pushover (MADP) analysis procedure, estimates the seismic demands of buildings by using several multi-stage modal pushover analyses. Each multi-stage pushover analysis begins with the lateral load pattern proportional to the elastic mode-shape. The pushover analysis is then continued with a new lateral load pattern, constructed based on the story displacements obtained from the previous stage. The lateral force distribution is changed whenever a new plastic hinge is formed in the inelastic structural model. The 'first-mode' inelastic mode-shape of the structure is also used by the MADP method to accurately estimate the value of the target-displacement. The final structural responses are determined by combining the seismic demands obtained by the multi-stage modal pushover analyses using an appropriate modal combination rule. The accuracy and efficiency of the MADP procedure is verified using the analysis of four special RC moment-resisting frames with 4-, 8-, 12-, and 20-stories. The structural responses are estimated for two different seismic hazards (intensities). A comparison is then carried out between the estimates from the MADP method with those given by the exact nonlinear response history analysis (RHA). The results from two advanced pushover analysis procedures including the modal pushover analysis (MPA) and consecutive modal pushover (CMP) methods are also presented for the purpose of comparison. The results show that the MADP method is able to satisfactorily estimate the critical seismic demands such as interstory drift ratio and the plastic rotation of the hinges for the example buildings, and to provide an advanced nonlinear static procedure for the seismic performance assessment of RC moment-resisting frames. [ABSTRACT FROM AUTHOR]

Nowadays, the application of the engineered cementitious composites(ECC) is expected to highly develop. Due to the lack of access to oiled- polyvinyl alcohol (PVA) fibers in many parts of the world, the implementation of the ECC has contained many difficulties. In this study, to increase the mechanical properties of ECC with the use of un-oiled PVA fibers, the polymers of styrene butadiene rubber (SBR), and ethylene vinyl acetate (EVA) were taken into account to resolve the abovementioned issue. Herein, also in order to enhance the tensile and flexural properties of ECC, the cement was replaced by polymers. Accordingly, a total of 7 mix designs were planned to conduct the proposed tests. The compressive strength, uniaxial tensile strength, and three-point bending tests were performed on the ECC at their 28-day age with consideration of the freeze and thaw cycle. The results of this research illustrated that the use of polymers can enhance the tensile and flexural properties of the ECC with un-oiled PVA fibers. The tensile strain in this study increased by more than 3% after the application of the polymers. Furthermore, the compressive strength increased by more than 47 MPa, and the deflection at the mid-span reached more than 9 mm in the bending test. However, the results showed that the use of polymers was effective on the freeze and thaw cycle and almost preserved the mechanical properties of the ECC. SBR latex has higher compatibility with the ECC in comparison with EVA powder. [ABSTRACT FROM AUTHOR]