Seismic Prone Areas Research Articles

Seismic performance of mid-rise thin concrete wall buildings lightly reinforced with deformed bars or welded wire mesh

The increasing demand of housing in urban areas in Latin America has driven the construction of a significant number of buildings using reinforced concrete (RC) walls with thickness equal or lower than 100 mm, with a single layer of reinforcement provided by a welded-wire mesh (WWM) or by deformed bars (DB). Several concerns related to the lack of ductility, scarce evidence on its behavior during earthquakes, and the lack of clarity of design guidelines in earthquake-resistant codes for this structural system have risen in recent years. This research aims at providing evidence on the seismic risk of thin concrete wall buildings reinforced with two types of reinforcement. A six-story building, constructed in Bogotá, Colombia with walls having 100 mm thickness and detailed with WWM is used as case study. After gathering relevant information from the building structural drawings, a nonlinear model was created in OpenSees using the shear-flexure interaction multiple vertical line element (SFI-MVLEM). To evaluate the effect of steel ductility, a second benchmark model of the studied building was created using deformed bars (DB) as reinforcement. Incremental dynamic analyses were conducted on the models using the far field ground motion suite provided by the FEMA P-695 and a set ground motions for subduction zones, which served as input for the development of fragility functions for the building. The results show that the fracture of reinforcing steel is a frequent failure mode of the building reinforced with WWM, whereas the failure of the building reinforced with DB was controlled by the drift limit of the walls. The findings also show that probabilities of failure for the ground motions scaled to the maximum credible earthquake are 41% and 25% for the building reinforced with WWM and DB, respectively. These large probabilities suggest that the use of thin RC walls for mid-rise buildings should be limited in seismic prone areas, especially those detailed with WWM.

Behaviour of Precast Column Foundation Connection under Reverse Cyclic Loading

Precast column foundation connection is one of the critical connections under reverse cyclic loading, and the present study focuses on this connection. Three types of connections were considered, such as (i) base plate connection, (ii) pocket connection, and (iii) grouted sleeve connection. All the above connections were designed, and experimental investigation was carried out on 1 : 2 scaled models by subjecting the column to lateral reverse cyclic loading. Displacement-controlled loading pattern has been adopted for the testing of the specimens. The structural response of the connection was studied for their (i) load-displacement hysteresis behaviour, (ii) stiffness degradation, (iii) energy dissipation, and (iv) ductility. The results were then compared with that of the monolithic connection. The precast connection was more ductile, and the energy dissipated by the pocket connection was high compared to the base plate and grouted sleeve connection. The ductility and the load-carrying of grouted sleeve connection were small compared to other connections. The results of the study showed the precast column foundation can be used in seismic prone areas.

Preface of destructive m

This study aims to denote the possible casualties and damages due to the M<5 earthquake. We used the desk study of literatures to explore earthquake disaster reports. The published significant and destructive earthquakes catalogue by BMKG Indonesia along 2015-2019 noted that six events out of them in Java island due to by below magnitude 5 (M<5) earthquakes. Those are sourced in the land and shallow depth focus on the active faults region. Those earthquakes also cause human losses, that is three events out of them induce casualties, and kill two (2) people. Preliminary analysis concludes that the short distance to earthquake source and local site condition was responsible for this unexpected building damages. We suggest this events to be the lesson learned for disaster risk managers to consider the low magnitude earthquake also able to generate the high hazard on the certain seismic prone areas.

Effects of Bracing System on Multistoryed Steel Building

In recent years, in regions of the highly seismic prone area, steel construction has changed from moment resistant frames to concentrically braced frames. To withstand earthquake forces, bracing part of the structural pattern by providing extra stiffness plays a crucial role in structural action. Concentric bracing in building frames is one of the most common horizontal load resistance patterns. For this reason, seven distinct models were created by changing the bracing pattern in the steel frame and analyzed for wind and seismic forces A 20-story steel frame structure is explored in this presented work. From this research, it can be inferred that the bracing factor will have a very significant impact on structural behavior under seismic loading. The most desirable bracing framework is the Backward bracing pattern. Horizontal displacement at the top floor is decreased by approximately 50 percent for Backward braced in frame structure compared to without bracing pattern.

Liquefaction hazards mapping along Rеd Sеa coast, Jеddah city, Kingdom of Saudi Arabia

This study mainly aims to evaluate as well as to develop maps of the liquefaction potential for Jeddah City in the Kingdom of Saudi Arabia. Data is obtained and used from 214 boreholes associated with standard penetration tests (SPT). Through taking into account comparable seismic hazardous situations to amax = 0.1 g, the liquefaction potential index (LPI) is measured. In order to compile the liquefaction hazard map, LPI values are correlated, showing the quantitative aspects of the liquefiable layers and the area of likelihood of induced disturbance. This data was analyzed within the framework of the Geographical Information Systems (GIS) application. The results show that, with the exception of the sites in the Abhur and Al-Hamra districts where the liquefaction potential is moderate to high, the main part of the city of Jeddah belongs to a very low liquefaction potential area. The developed liquefaction hazard maps will serve as helpful guides for land planning and management in Jeddah city. In addition to that, they serve as an example of the evaluation of the liquefaction hazard that can also be found in other developed cities in the seismic-prone areas of southern and eastern Saudi Arabia.

Upgraded formulations for the onset of local mechanisms in multi-storey masonry buildings using limit analysis

Unreinforced stone masonry (URSM) buildings without a box-like behaviour are very vulnerable to out-of-plane failure modes in seismic prone areas. These may involve partial or total collapses of walls with severe civil protection implications in terms of hazard to people, structures, and road network in the surroundings.In this paper, an advanced macro-block model accounting for frictional resistances is used to calculate the onset load factors for two classes of local mechanisms in multi-storey URSM buildings: the rocking-sliding and the flexure mechanisms. Based on the application of the kinematic approach of limit analysis, the presented formulations are an upgrade of the load factors identified within the FaMIVE (Failure Mechanism Identification and Vulnerability Evaluation) procedure existing in the literature and developed by the last author. These take into account a revisited evaluation of the in-plane frictional forces for the rocking-sliding mechanisms and the torsion-shear-flexure interactions for the horizontal flexure mechanisms. Moreover, the position of the hinge along the height of the building is identified more accurately, since it can be found at the story level or between two storeys, depending on the accounted mechanism. Other innovative issues concern upgrades of the former formulations for the vertical and horizontal flexure mechanisms.The final perspective of the presented abacus of local mechanisms in multi-storey URSM buildings is the next implementation of the proposed formulations in the FaMIVE procedure, after a sensitivity analysis of the main physical and geometrical parameters affecting the “hierarchy” among the all possible mechanisms. The identification of the most probable mechanisms, through a comprehensive but at the same time relatively rapid assessment, can be very useful for civil protection purposes.

On numerical investigation of stability of roadbeds reinforced by gabion structures

The stability of roadbed in seismic prone areas is vital for the sustainable economic development of regions. The gabion structures are one of the methods of road strengthening. Gabion structures are used to avoid damage to the roadbed under loads of natural ground slope due to earthquake or other reasons. This approach is one of the most economical and efficient solutions for the stabilization of natural ground slopes, and it is efficient as a drainage system. Field tests give precise results about the efficiency of gabion types for different sites. However, in some cases, it is expensive and numerical calculation can be used for the estimation of the applicability of gabions. The stability of roadbed by using finite element approaches was investigated here. Stability was considered as results of calculations by two cases with gabions and without ones were compared. The dynamic and seismic impact was taken into account according to local normative documents.

The influence of exposed to corrosion length of rebars on fatigue life of RC elements

Deterioration of reinforced concrete is a main factor on estimation of structures' service lifetime. As it is well known, both corrosion of steel reinforcement and earthquake events, have detrimental effects on structural integrity of RC elements. In this study, the fatigue life of corroded reinforcement is investigated. Bare and embedded (in concrete) specimens of rebars are tested in low cycle fatigue conditions after accelerated corrosion experiments using impressed current technique. Corrosion damage, in terms of mass loss, and the mechanical tests of fatigue are taken account in function of the exposed to corrosion length of reinforcement. The outcomes attained from the experimental study indicate higher mass loss values of specimens with short exposed to corrosion length than the corresponding mass loss values of specimens with long exposed to corrosion length at the same tested corrosion time; subsequently resulting in their reduced fatigue lifetime. Extrapolating the abovementioned results on RC elements in marine environment located in seismic prone areas, issues are raised concerning the assessment of structural integrity and the parameters which are taken into account on monitoring of high importance structures.

Modified pseudo-dynamic analysis of rigid gravity retaining wall with cohesion-less backfill and uniform surcharge

An increase in failure of geotechnical structures is a significant concern in seismic-prone areas. The purpose of the study is to propose a closed-form solution for the seismic active pressure acting on a retaining wall with backfill subjected to uniform surcharge considering the propagation of both shear and primary waves. The proposed study considers the damping ratio by assuming soil as Kelvin-Voigt material. The proposed methodology satisfies boundary conditions at the surface of the backfill due to surcharge. The deduced acceleration profile is considered for the estimation of inertial forces due to critical wedge and surcharge. The study reveals that the maximum seismic active pressure coefficient occurs when the normalized input frequency is equal to π/2. It is observed that the surcharge magnitude does not affect both horizontal and vertical acceleration profiles. The parametric study presents the influence of various static and dynamic properties of the backfill soil on the distribution of seismic pressure acting on the wall. The coefficient of earth pressure obtained from the proposed method is in good agreement with the existing pseudo-static methods. It is concluded that the effect of shear wave propagation on earth pressure is relatively dominant as compared to that of primary wave propagation.

Micro and Macro Structural Investigations on Welded Joints of Composite Truss Steel Concrete Beams

The results of an experimental test campaign including micro and macro investigations on welded joints typically used in Composite Truss Steel‐Concrete beams are presented. The research was carried out with the aim of assessing the relevance of welding effects on the mechanical performance of different typologies of steel grades that can be used to realize the internal truss steel system, connected to the bottom steel plate used with the double structural and formwork function. Two different steel typologies were adopted for the steel truss: the “traditional” structural micro‐alloyed steel, normally used for composite steel‐concrete elements, and the typical reinforcing steel with TempCore® structure, achieved through the application of two‐phase thermomechanical treatment of quenching and tempering. The interest in the possibility of adopting reinforcing steel for the internal truss arises from its potential economic benefit, finding its justification in the intermediate condition in which this structural typology lies, between composite steel‐concrete and ordinary reinforced concrete buildings. Welding has a strong impact on such reinforcing steel material, resulting in relevant drops of ductility and brittle failure usually taking place in correspondence of the heat‐affected zone. So, it is advisable to refrain from using such steel grade, especially in constructions in seismic‐prone areas, where ductility is a major influencing and design factor.

Residual displacements for non-degrading bilinear oscillators under seismic actions

This work aims to provide a relationship to assess the residual displacements for one-storey buildings standing in seismic-prone areas. The maximum residual displacement that a structure can possibly sustain is clearly identified by means of its structural characteristics alone. It is demonstrated that the upper bound is independent of the peak displacement. The proposed procedure can help in controlling the structural residual deformations, which is an issue that is gaining momentum into the seismic community: a large body of research has been dealing with post-seismic damage. However, no general rule or theoretical mechanic model with general validity are reported in the literature. The solely valuable approach, though widely accepted, for predicting seismic-induced residual displacements is a statistical one. In order to frame the given relationship into the established probabilistic framework, an extensive numerical campaign has been carried out by means of nonlinear time-history analyses. Artificial spectrum-compatible accelerograms are used as proxies to account for seismic events. As a final result, residual displacement response spectra are proposed.

The Strengthening of Masonry Walls in Seismic-Prone Areas with the CAM System: Experimental and Numerical Results

In this paper, experimental and numerical results of a research project about the structural behavior of strengthened masonry are presented and discussed. The aim of the research is to study the in-plane shear behavior of an old masonry wall with an opening in the arch form, reinforced with a pioneering system of 3D pre-tensioned stainless steel ties. The masonry wall was in-plane loaded until first cracking appeared, then it was reinforced and re-loaded until failure. The experimental results have highlighted the benefits of the reinforcing method adopted, especially to provide an increasing in terms of both strength and ductility. Numerical modeling of the masonry wall behavior was accomplished by using non-linear finite-element methods generally adopted for reinforced concrete elements.

Optimum life-cycle maintenance strategies of deteriorating highway bridges subject to seismic hazard by a hybrid Markov decision process model

Highway bridges are a class of important infrastructure components in transportation networks. Highway bridges will inevitably deteriorate over time due to various external impacts, such as traffic loads and corrosion. In seismic-prone areas, seismic hazard is another critical factor that threatens the normal operation of ageing highway bridges. To ensure adequate safety of ageing highway bridges under potential earthquake shocks, it is imperative to perform proper maintenances during their service life. This paper aims at optimizing the life-cycle maintenance strategies for highway bridges under the combinatorial threats of progressive deterioration and sudden earthquakes. Driven by the distinct characteristics of the two threats, we have proposed a novel hybrid Markov decision process model that integrates a discrete-time Markov decision process model for dealing with progressive deterioration and a continuous-time Markov decision process model for dealing with sudden earthquakes into a unified framework. The proposed model is further reduced into the form of a discrete-time Markov decision process model with an equivalent state transition matrix and an equivalent discount factor, which can be easily solved by dynamic programming. A ternary state space that collectively describes corrosion initiation, corrosion damage cumulation, and seismic damage cumulation is defined. A gamma process and a Poisson process are adopted to model bridge corrosion and earthquake occurrences, respectively. To demonstrate the application of the proposed framework, a numerical example is conducted, in which the optimizations with respect to the maintenance strategy, inspection interval, and design performance level of a hypothetical highway bridge are carried out successively.

Three-dimensional stress analysis and design of cross-laminated timber panels using full-layerwise-theory-based finite element method

Cross-laminated timber (CLT) panels have an increasing market share and extensive application in civil engineering, as full size walls or light floor structures. Due to their low environmental impact, excellent thermal characteristics and high mechanical performance, they are being extensively applied instead of conventional mineral-based building materials. Thick and orthogonal structure of CLT provides the considerable stiffness with the low weight and makes such panels particularly suitable in seismic-prone areas. The ease of assembly allows prefabrication and reduces construction time and cost.Current models for calculating the stress-deformation state of a CLT loaded out-of-plane mainly emerged from the long tradition of using very simple one-dimensional (beam-like) elements in timber structures. The paper tends to overcome some limitations of the current models by using the full-layerwise plate theory (FLWT) of Reddy, serving as a basis for the implementation of layered finite elements. The proposed model accounts for the complex 3D stress state in CLT loaded out-of-plane and implies an original procedure for stress calculation. It is implemented using the original object-oriented MATLAB framework, while the graphical user interface for pre- and post-processing is developed using GiD.The presented approach is validated using the available numerical and experimental data in the literature, and compared against the commonly used methods for the design of CLT. Finally, the 3D stress-deformation state in the CLT slab of complex shape (commonly used in building structures) is obtained using the FLWT-based finite elements. The results are validated against the numerical data from the commercial software, and then used for checking of the ultimate and serviceability limit states for CLT slab according to Eurocode 5. Excellent agreement of the obtained results confirmed the potential of the proposed model to become a promising tool for engineering design of CLT slabs of arbitrary geometry.

Ductile and dry exterior joints using CFRP bolts for moment-resisting frames

This study proposes a new dry joint type for moment-resisting frames by using carbon fibre reinforced polymer (CFRP) bolts and plates. This is one of very rare studies focusing on the potential of using CFRP bolts to connect the precast beam-column joints. CFRP bolts have been recognized for their good performances, which could effectively resolve a very costly issue of corrosion in the common dry joints using steel bolts, plates, and tendons. Cyclic loading was applied to test four specimens until 85% of the post-peak load. The results indicated that the proposed dry joints showed better performances compared to the reference monolithic joint in the load-carrying capacity, energy dissipation, and stiffness, which increased by 27–61%, 45–75%, and 27–55%, respectively. Particularly, drift ratio of all the proposed joints exceeded 3%, which is higher than the requirements for ductile joints in various standards. The ductility of the proposed joints was also more preferable than the reference monolithic joint (i.e. 2.2 vs 2.4). These exciting results suggest that these new dry joints can be plausibly applied to prefabricated constructions in non-seismic and seismic-prone areas. In addition, the proposed dry joints offer numerous advantages, compared to the traditional monolithic joints, in terms of construction time and construction-quality control.

A simple and safe brick masonry infill construction for high seismic-prone area

West Sumatera Province has been known as one of the high seismic-prone areas in Indonesia. In this area, peoples commonly use the brick masonry as infill in the Reinforced Concrete (RC) frame structures. Field investigation after the earthquake informed that there were many bricks masonry infill collapsed caused by the earthquake motion. In this study, a simple and safe brick masonry infill construction in the RC frame structure is proposed for applying in the high seismic-prone area such as West Sumatera. The proposed construction method was defined based on the experimental works of the three 1/4 reduced-scale singe-bay and single-story RC frame specimens. The specimens include one specimen of RC frame infilled with brick masonry, one specimen of RC frame infilled with strengthened brick masonry by using chicken wire mesh, and one specimen of RC frame infilled with brick masonry infill and anchored to the columns with plain steel rebars. The wire mesh was sewn on both sides of the diagonal area of the brick masonry infill. All the specimens have subjected to lateral static reversed loading. The structural test results have shown that the strengthening using the chicken wire mesh increase the lateral strength of the RC frame about 22.%, while the use of the plain rebars anchor decreases the lateral strength about 1.8% and both methods can delay the failure of the brick masonry infill.

Susceptibility to Seismic Amplification and Earthquake Probability Estimation Using Recurrent Neural Network (RNN) Model in Odisha, India

The eastern region of India, including the coastal state of Odisha, is a moderately seismic-prone area under seismic zones II and III. However, no major studies have been conducted on earthquake probability (EPA) and hazard assessment (EHA) in Odisha. This paper had two main objectives: (1) to assess the susceptibility of seismic wave amplification (SSA) and (2) to estimate EPA in Odisha. In total, 12 indicators were employed to assess the SSA and EPA. Firstly, using the historical earthquake catalog, the peak ground acceleration (PGA) and intensity variation was observed for the Indian subcontinent. We identified high amplitude and frequency locations for estimated PGA and the periodograms were plotted. Secondly, several indicators such as slope, elevation, curvature, and amplification values of rocks were used to generate SSA using predefined weights of layers. Thirdly, 10 indicators were implemented in a developed recurrent neural network (RNN) model to create an earthquake probability map (EPM). According to the results, recent to quaternary unconsolidated sedimentary rocks and alluvial deposits have great potential to amplify earthquake intensity and consequently lead to acute ground motion. High intensity was observed in coastal and central parts of the state. Complicated morphometric structures along with high intensity variation could be other parameters that influence deposits in the Mahanadi River and its delta with high potential. The RNN model was employed to create a probability map (EPM) for the state. Results show that the Mahanadi basin has dominant structural control on earthquakes that could be found in the western parts of the state. Major faults were pointed towards a direction of WNW–ESE, NE–SW, and NNW–SSE, which may lead to isoseismic patterns. Results also show that the western part is highly probable for events while the eastern coastal part is highly susceptible to seismic amplification. The RNN model achieved an accuracy of 0.94, precision (0.94), recall (0.97), F1 score (0.96), critical success index (CSI) (0.92), and a Fowlkes–Mallows index (FM) (0.95).

A Genetic Algorithm adaptive homogeneous approach for evaluating settlement-induced cracks in masonry walls

This paper presents a Genetic Algorithm adaptive homogeneous approach aiming at representing the crack patterns induced by ground settlements on masonry walls. This type of damage is a critical issue since it affects all masonry buildings, including those that are not located in seismic-prone areas. The GA-adaptive homogeneous approach here proposed is meant as a tool that overcomes the usual high computational costs requested by the traditional heterogeneous and homogeneous approaches. Here, the considered masonry wall is discretized into a low number of 2D polygonal elements; its displacement field is then determined through a linear programming problem. The actual position of cracks induced by the applied settlement is identified by modifying the initial mesh through an iterative mesh adaptation procedure performed with a Genetic Algorithm (GA); the iterations are carried on until the absolute minimum of the work performed by the reaction forces is attained. In this way, the computational effort needed for identifying the actual crack patterns is dramatically decreased due to the very few unknowns of the problem. The reliability of the GA-adaptive homogeneous approach here proposed is validated against selected benchmarks that come from experimental and numerical results, and is also compared with the traditional heterogeneous and homogeneous approaches. In all the three benchmarks, the GA-adaptive approach offers a satisfying computational efficiency and identifies the actual crack patterns with good accuracy, despite the low number of elements employed in the discretization of the masonry wall. This may pave the way for a broader use of this approach in the analysis of complex masonry structures affected by settlement-induced damages.

Preliminary Investigation of Seismicity in Parts of North Central Nigeria, Using High Resolution Aeromagnetic Data

Qualitative analysis of Aeromagnetic data of parts of north central Nigeria had been carried out with the aim to delineate seismic prone areas. The study area is bounded with latitude 9. 00o to 10. 00oN and longitude 7.00o to 9.00oE with an estimated total area of 24,200 km2. Vertical derivatives and upward continuation filters were used to enhances long wavelength anomalies which could give preliminary information about the magnetic structures present in the study area. The total magnetic intensity map shows both positive and negative anomalies with susceptibility ranging from 33487.7 nT to 33800.9 nT. The high magnetic susceptibilities dominated in the basement region around the north-eastern and north-western parts of the study area which corresponds to Naraguta, Jemma and Kafanchan area. Based on the geology of the area this is attributed to granite, schist and migmatite rocks. The low magnetic values are made of sediment deposition also dominates the south-western part of the study area, corresponding to Abuja and Gitata. The area with magnetic susceptibility values ranging between 33506.6 nT and 33653.8 nT indicates alluvium deposite around Bishini and Kachia area. Lineament from First Vertical Derivative trend in the northeast-southwest and east-west directions, which is an extension from Romanche Fracture Zone. Majority of this lineament trends in the same directions as the Romanche Fault Line which continues at 25 km and 30 km into n inferred closure within the study area which is trending along north-west direction. This, closure occurs probably because of the existence of the paleo fracture zone (Romanche Fracture Zone) within the study area. At 40 km and at 80 km a regional trend in the NE-SW direction in (porphyritic) basement rocks. At the northeast and southeastern part of the area which is made up of basement complex that corresponds to areas around Gitata, Kafanchaan and Jemma are prone to tectonic activities while the southwestern part of the area around Abuja is seismic free. It is suggested that those lineaments identified, most especially at the southeastern part could be the reason for the shaking of the subsurface which result into earth tremors.

Shear strength model for steel reinforced concrete composite members: Short columns and deep beams

Steel reinforced concrete (SRC) composite members, in which a steel shape is encased in a reinforced concrete section, are widely used in high-rise buildings in seismic-prone areas, and the accurate shear strength prediction of SRC shear-critical members is still under investigation by researchers and code-writers. The current code-based design method is acceptable for determining the shear strength of SRC members because of the feasibility and simplification compared with other complicated calculation models. Nevertheless, the code-based design method is usually established on the basis of the strength superposition method, indicating that the overall shear strength of a SRC member is obtained as the sum of the shear strength of the steel shape and that of the reinforced concrete. Although the strength superposition method is simple and feasible, the shear strengths of these two parts usually cannot reach the corresponding peak point at the same time, which may lead to an unsafe result. This research presents a theoretical model for predicting the shear strengths of SRC deep beams and SRC short columns. In this model, the concept of strength superposition is applied, and the shear strength of the steel shape and that of the reinforced concrete part are calculated using comprehensive models and related according to the shear deformation. Finally, the proposed model is compared with other calculation methods from codes Eurocode 4, AISC 360, JGJ 138 and YB 9082 using the available test data consisting of 63 SRC short columns and 57 SRC deep beams, and it can be concluded that the proposed model is capable of calculating the shear strengths of SRC short columns and SRC deep beams with sufficient accuracy and safety.