Incremental Dynamic Analysis Technique Research Articles

Developed drift damage index-based failure criterion for framed-wall structure system

Recently, significant progress has been observed in high-rise buildings, positively affecting the economy and society. Since the damage and failure of these structures could cause tremendous disasters for society and humanity, investigating the damage performance of the building and assessing this damage is urgently needed. The numerical methods combined with the damage mechanics theory have shown to be a crucial tool to simulate and capture the damage of these structures. Therefore, this study introduces an effective simulation procedure and performs the non-linear dynamic analysis of a framed-wall structure with different heights under various seismic events and intensities using the incremental dynamic analysis technique. The tensile damage is well captured through the adopted damage model, and it is illustrated that the damage initiation and propagation are varied at different seismic events, which significantly affects the structure response. Moreover, an extensive study on the damage assessment has been provided to evaluate the damage degree of the structure using the Park-Ang damage index. The key point of this study is to recognize an efficient criterion to determine the structure’s state under different dynamic loads. Accordingly, a new formula has been proposed to quantify the damage to the framed-wall structures efficiently with low computational efforts, which will be of great importance in the case of assessing the damage for the city-scale model rapidly. This study demonstrated that the proposed formula could accurately assess the damage induced in the framed-wall structures where the results agree with the calculated values through the Park-Ang damage index. Finally, the results of the collapse state have been emphasized through the collapse analysis, which proves the efficiency and reliability of the proposed formula.

Myths and realities of endurance time analysis: Discussion/Comments Regarding “Seismic assessment of deep water bridges in reservoir considering hydrodynamic effects using endurance time analysis” by Yutao Pang, Li Cai, Wei He, and Li Wu; Ocean Engineering, 2020, 198:106846

This discussion is based on the paper by Pang et al. (2020) (hereafter identified as “the original authors” and “the original paper” or “the reference paper”). The original authors employed the endurance time analysis (ETA) and incremental dynamic analysis (IDA) techniques to investigate the probabilistic response of a deep water bridge in a reservoir. They derived multiple fragility curves using both techniques. Derivation of ETA-based fragility functions in the original paper is not fully consistent with the nature of seismic fragility curves. The underpinning concept of fragility curves is tied with ground motion record-to-record (RTR) variability, while the conventional ETA does not offer such an ability. We discussed several underlying assumptions in the ETA method, as well as different sources of ground motion RTR variability (from IDA technique) which may affect the logarithmic dispersion in a fragility curve (and it is unseen in conventional ETA method).

A simplified method for probabilistic seismic risk evaluation of nuclear containment structure

Damage performance and annual frequency of exceedance are the focus of probabilistic safety assessment for nuclear power plant structures. However, conventional displacement-based global damage index and classical method for calculating the annual frequency of exceedance of the nuclear containment structure suffers from some limitations and deficiencies. Based on seismic energy balance concept, an innovative energy-based global damage index is proposed in this study. Based on truncated incremental dynamic analysis (TIDA) technique, a simplified method for calculating the annual frequency of exceedance of the nuclear containment structure is developed. To verify the effectiveness of the proposed global damage index and the proposed simplified method for calculating the annual frequency of exceedance, the proposed energy-based global damage index is compared to roof displacement based damage index. The annual frequency of exceedance calculated by the simplified method is compared to a more accurate but computationally demanding approach (full incremental dynamic analysis technique based approach). Finally, statistics of the annual frequency of exceedance are estimated by the parametric bootstrap method. Results indicated that energy-based global damage index proposed in this study can well reflect the global deformation characteristics of the nuclear containment structure. The variability of the proposed global damage index is smaller than that of roof displacement based global damage index, which indicates the superiority of the proposed global damage index. In general, the proposed simplified method for calculating the annual frequency of exceedance can provide good estimation of the annual frequency of exceedance of the nuclear containment structure corresponding to different damage levels. With regard to the statistics of the annual frequency of exceedance, the mean value of the annual frequency of exceedance is not sensitive to the number of bootstrap samples, while the coefficient of variation of the annual frequency of exceedance is sensitive to the number of bootstrap samples. When the number of bootstrap samples is larger than 300, the statistics of the annual frequency of exceedance tend to be stable.

Damage performance based seismic capacity and fragility analysis of existing concrete containment structure subjected to near fault ground motions

Containment structures fill the critical role of providing the final barrier against release of radioactive materials. Near fault earthquake pose great threaten to the function of existing containment structure. There is a growing necessity of performing a detailed seismic capacity and fragility analysis of existing containment structure. This paper presents seismic capacity and fragility analysis of existing containment structure subjected to near fault ground motions from damage performance based perspective. To capture uncertainties associated with the ground motions, incremental dynamic analysis technique is conducted, and three damage levels are proposed based on tensile damage factor provided in concrete damaged plasticity (CDP) model. Fragility curves of containment structure under minor damage, moderate damage and severe damage is obtained with MATLAB optimization program. Results of this study reveal that tensile damage of containment structure within 8 m of the bottom of the containment is most vulnerable locations in containment structure. The bottom location of the containment structure is dominant by bending cracks, and the lower location of the containment structure (except the bottom location) is governed by diagonal shear cracks. With the increase of ground motion intensity, shear behavior of the containment structure becomes more obvious.The HCLPF seismic capacity of this containment structure under minor damage, moderate damage and severe damage is 0.452 g, 0.631 g and 0.790 g, respectively.

Seismic demand on steel reinforcing bars in reinforced concrete frame structures

Modern design standards for reinforced concrete (r.c.) buildings allow the achievement of ductile structures, able to globally dissipate seismic energy through the development of plastic deformations located in the dissipative regions (i.e. plastic hinges). The hysteretic capacity of r.c. structures is related to the ability of reinforcing steel bars to sustain many cycles of high plastic deformations without the exhibition significant decrease of strength and stiffness; this condition, typically due to cyclic/seismic action, shall be widely investigated in order to obtain a full and detailed knowledge of the structural behaviour of modern r.c. buildings. In the present paper, elaborated inside the European research project “Rusteel”, the evaluation of the seismic ductile demand on steel reinforcing bars due to real earthquake events was carried out. Representative r.c. case study buildings were designed following the actual European and Italian prescriptions and analyzed using the Incremental Dynamic Analysis technique for the assessment of the behaviour under real seismic events. The elaboration of a simplified mechanical model for the steel reinforcing bars, calibrated on the basis of experimental monotonic and cyclic tests, allowed the evaluation of the effective level of deformation and energy dissipation required by earthquakes and the assessment of the ability of the actual European production to satisfy the effective seismic ductile requirements.

Incremental dynamic analysis of steel frames equipped with NiTi shape memory alloy braces

SUMMARYThis paper determines the seismic performance of four‐storey concentrically braced frames equipped with either steel buckling‐restrained braces or buckling‐restrained superelastic shape memory alloy (SMA) braces through incremental dynamic analysis. The incremental dynamic analysis technique is used to examine the behaviour of four‐storey braced frames with four different bracing configurations (including diagonal, split‐X, chevron‐V and inverted‐V) under 20 different ground motion records. The study reveals a satisfactory performance at the design intensity level for both types of braced frames. The results show that the SMA braces lead to a uniform distribution of inelastic response over the height of the buildings, as well as mitigating seismic response in terms of maximum inter‐storey drift and residual roof displacement. By comparing the responses of SMA and buckling‐restrained braced frames under higher intensities of earthquake loading, it is found that the SMA braces can be more beneficial especially under severe ground motion excitations. Copyright © 2014 John Wiley & Sons, Ltd.

Seismic Vulnerability Assessment of Multistory Timber Braced Frame Traditional Masonry Structures

Research carried out on the seismic investigation of timber braced frame (TBF) masonry structures of traditional construction practice is presented, essential for seismic performance evaluation of such construction type using engineering approaches. An innovative simplified equivalent frame method (EFM) based on macro modelling approach is presented for nonlinear dynamic seismic analysis of TBF masonry structures. The modelling include EFM idealization of wall using stiff elastic beam-column element assigned with moment-rotation (M-θ) nonlinear lumped plasticity hinges. Earlier, the approach i.e. the EFM idealization and M-θ constitutive law, is calibrated with the experimental results obtained through quasi-static cyclic test on full scale walls. The technique is further extended herein for seismic dynamic analysis of multistory structures. Generalization of the technique for modelling walls of various geometry and loading is performed. It included nonlinear static pushover analysis of various case study walls, by means of SAP2000 calibrated earlier with experimental results, for the derivation of lateral force-deformability behavior towards the development of generalized M-θ constitutive law for TBF masonry walls. Three representative structures, from one to three storeys, are analyzed using a suite of ten natural accelerograms and incremental dynamic analysis technique. Structure fragility and resilience functions are derived using a fully probabilistic and dynamic approach. The structures analyzed in the present study represent TBF masonry wall structures, called as Dhajji-Dewari structures, common in Northern areas of Pakistan.

Seismic vulnerability of the Himalayan half-dressed rubble stone masonry structures, experimental and analytical studies

Abstract. Half-Dressed rubble stone (DS) masonry structures as found in the Himalayan region are investigated using experimental and analytical studies. The experimental study included a shake table test on a one-third scaled structural model, a representative of DS masonry structure employed for public critical facilities, e.g. school buildings, offices, health care units, etc. The aim of the experimental study was to understand the damage mechanism of the model, develop damage scale towards deformation-based assessment and retrieve the lateral force-deformation response of the model besides its elastic dynamic properties, i.e. fundamental vibration period and elastic damping. The analytical study included fragility analysis of building prototypes using a fully probabilistic nonlinear dynamic method. The prototypes are designed as SDOF systems assigned with lateral, force-deformation constitutive law (obtained experimentally). Uncertainties in the constitutive law, i.e. lateral stiffness, strength and deformation limits, are considered through random Monte Carlo simulation. Fifty prototype buildings are analyzed using a suite of ten natural accelerograms and an incremental dynamic analysis technique. Fragility and vulnerability functions are derived for the damageability assessment of structures, economic loss and casualty estimation during an earthquake given the ground shaking intensity, essential within the context of risk assessment of existing stock aiming towards risk mitigation and disaster risk reduction.

Incremental dynamic analysis of concrete moment resisting frames reinforced with shape memory composite bars

Fiber reinforced polymer (FRP) reinforcing bars have been used in concrete structures as an alternative to conventional steel reinforcement, in order to overcome corrosion problems. However, due to the linear behavior of the commonly used reinforcing fibers, they are not considered in structures which require ductility and damping characteristics. The use of superelastic shape memory alloy (SMA) fibers with their nonlinear elastic behavior as reinforcement in the composite could potentially provide a solution for this problem. Small diameter SMA wires are coupled with polymer matrix to produce SMA–FRP composite, which is sought in this research as reinforcing bars. SMA–FRP bars are sought in this study to enhance the seismic performance of reinforced concrete (RC) moment resisting frames (MRFs) in terms of reducing their residual inter-story drifts while still maintaining the elastic characteristics associated with conventional FRP. Three story one bay and six story two bay RC MRF prototype structures are designed with steel, SMA–FRP and glass–FRP reinforcement. The incremental dynamic analysis technique is used to investigate the behaviors of the two frames with the three different reinforcement types under a suite of ground motion records. It is found that the frames with SMA–FRP composite reinforcement exhibit higher performance levels including lower residual inter-story drifts, high energy dissipation and thus lower damage, which are important for structures in highly seismic zones.