Seismic Resistance Of Buildings Research Articles

Prediction of Structural Response Based on Ground Acceleration Using Artificial Neural Networks

This study utilizes Artificial Neural Network (ANN) to predict structural responses of multi-storey reinforced concrete building based on ground acceleration. The strong ground acceleration might cause catasthropic collapse of multi-storey building which leads to casualties and property damages. Therefore, it is imperative to properly design the multi-storey building against seismic hazard. Seismic-resistant building design process requires structural analysis to be performed to obtain the necessary building responses. Modal response spectrum analysis is performed to simulate ground acceleration and produce structural response data for further use in the ANN. The ANN architecture comprises of 3 layers: an input layer, a hidden layer, and an output layer. Ground acceleration parameters from 34 provinces in Indonesia, soil condition, and building geometry are selected as input parameters, whereas structural responses consisting of acceleration, velocity and displacement (story drift) are selected as output parameters for the ANN. As many as 6345 data sets are used to train the ANN. From the overall data sets, 4590 data sets (72%) are used for training process, 877 data sets (14%) for the validation process, and 878 data sets (14%) for testing. The trained ANN is capable for predicting structural responses based on ground acceleration at (96%) rate of prediction and the calculated Mean-Squared Errors (MSE) as low as 1.2.10−4. The high accuracy of structural response prediction can greatly assist the engineer to identify the building condition rapidly and plan the building maintenance routinely.

Buildings Stability Revaluation in Seismically Active Regions

In 2015 the maps of seismic zoning on the territory of Russia were detailed according to new general standards (ОSR-2015). Compared to the previous data, the number of seismically dangerous areas has the tendency to increase. Most buildings in those areas of the country were designed and constructed as less earthquake resistant. The physical and mechanical characteristics of the soil in the buildings foundation are being changed under the influence of different ecological, engineering, geological, and man-made factors. The latest research discovers the high level of soil influence on seismic resistance of buildings. Further detailed examination of earthquake resistance of buildings in the northern territories of Russia has been planned according to the changes and influences mentioned above in order to lower the earthquake risks.

ИССЛЕДОВАНИЕ УСТОЙЧИВОСТИ ЗДАНИЙ И СООРУЖЕНИЙ К СЕЙСМИЧЕСКИМ КОЛЕБАНИЯМ В ГОРОДЕ АЛМАТЫ

In this paper, we estimate the stability of buildings and structures for seismic fluctuations in theAlmaty city, because frequent earthquakes threaten to life and health of population. In conditions ofconstant expansion and construction, we always must always worth considering the seismic resistanceof buildings, because threaten to life of population during earthquakes is the basis for the beginning oferection of structures. To remain unharmed among in the seismic zone. The aim is to study the conditionof buildings in Almaty on characteristics of seismic safety. Objectives of the study: - study of common types of buildings in Almaty;- carrying out calculations of the stability of buildings;We used the method of analysis of the common types of buildings and structures of the city, measuringtheir resistance to seismic vibrations. This article shows the calculation of the stability levels ofbuildings in different parts of the city to seismic fluctuations. Data are given on the levels of design seismicresistance of most of the structures, possible indicators of their stability are calculated. As the resultsshowed, the stability of buildings and structures of the city directly depends on their location on the citymap, which is due to the reduction of seismic activity in the direction from the lower part to the upperone. According to the conclusion, it is necessary to increase the number of design organizations responsiblefor the quality of construction, as well as to use a different structure and approach to the erection ofbuildings in different parts of the city.

Seismic performance of steel MRF building with nonlinear viscous dampers

This paper presents an experimental study of the seismic response of a 0.6-scale three-story seismicresistant building structure consisting of a moment resisting frame (MRF) with reduced beam sections (RBS), and a frame with nonlinear viscous dampers and associated bracing (called the DBF). The emphasis is on assessing the seismic performance for the design basis earthquake (DBE) and maximum considered earthquake (MCE). Three MRF designs were studied, with the MRF designed for 100%, 75%, and 60%, respectively, of the required base shear design strength determined according to ASCE 7-10. The DBF with nonlinear viscous dampers was designed to control the lateral drift demands. Earthquake simulations using ensembles of DBE and MCE ground motions were conducted using the real-time hybrid simulation method. The results show the drift demand and damage that occurs in the MRF under seismic loading. Overall, the results show that a high level of seismic performance can be achieved under DBE and MCE ground motions, even for a building structure designed for as little as 60% of the base shear design strength required by ASCE 7-10 for a structure without dampers.

Determination of the seismic performance factors for post‐tensioned rocking timber wall systems

SummaryPost‐tensioned technologies for concrete seismic resistant buildings were first developed in the 1990s during the PREcast Seismic Structural Systems program. Among different solutions, the hybrid system proved to be the most resilient solution providing a combination of re‐centering and energy dissipative contributions respectively by using post‐tensioned tendons and mild steel reinforcement. The system, while providing significant strength and energy dissipation, reduces structural element damage and limits post‐earthquake residual displacements. More recently, the technology was extended to laminated veneer lumber (LVL) structural members, and extensive experimental and numerical work was carried out and allowed the development of reliable analytical and numerical models as well as design guidelines. On the basis of the experimental and numerical outcomes, this paper presents the evaluation of the seismic performance factors for post‐tensioned rocking LVL walls using the FEMA P‐695 procedure. Several archetype buildings were designed considering different parameters such as the building and story height, the type of seismic resistant system, the magnitude of gravity loads and the seismic design category. Lumped plasticity models were developed for each index archetype to simulate the behavioral aspects and collapse mechanisms. Non‐linear quasi‐static analyses were carried out to evaluate the system over‐strength factor; moreover, non‐linear time history analyses were performed using the incremental dynamic analysis concept to assess the collapse of each building. From the results of quasi‐static and dynamic analyses the response modification factor, R, system over‐strength factor, Ω0, and deflection amplification factor, Cd, values of, respectively, 7, 3.5 and 7.5 are recommended. Copyright © 2016 John Wiley & Sons, Ltd.

Modelling and simulation of earthquake resistant 3D woven textile structural concrete composites

Concrete is a composite material composed of water, sand, coarse granular material called aggregate and cement that fills the space among the aggregate particles and glues them together. Conventional building structures are made up of steel skeleton with concrete impregnation. These are very heavy weight structures with steel vulnerable to corrosion. The conventional concrete structures tend to undergo large deformations in the event of a strong earthquake. Mechanical simulation of various textile structural concretes is carried out successfully for their ductility behaviour. 3D woven reinforced concretes display superior ductile character showing ray of hope to develop seismic resistant building. Simulation of three 3D woven fabrics and their composites was carried to predict ductility and strengths of fabric reinforced concrete structures. Maximum deformation was observed for beam reinforced with orthogonal interlock fabric under the same load and minimum deformation was observed for plain concrete. Maximum equivalent stress was observed to be highest for plain concrete followed by beam reinforced with angle interlock fabric followed by orthogonal fabric and warp interlock fabric under similar loading conditions. From the results it was clear that 3D fabric reinforced structures are more ductile than the traditional steel reinforced structures. Hence 3D fabric reinforced concrete structures are much better in strength and ductility as compared to conventional construction materials. Among the three 3D fabric, orthogonal fabric reinforced composites are most ductile and are also less stiff. They can deform more than the other two fabric composites. Hence, orthogonal fabric reinforced composites can undergo higher deformations without collapsing. These composites can be more elastic under earthquake shaking.

Extended end-plate to concrete-filled rectangular column joint using long bolts

This paper presents a research on a solution of extended end-plate joints, used to connect I-shaped beams to filled-concrete rectangular hollow section columns. In the joint, long bolts throughout the column are used to connect the beam end-plates. The main idea is to avoid intermediate connecting elements (e.g. a reverse U channel) or special bolts (e.g. blind bolts/flowdrill connectors) that are usually adopted in the beam to rectangular hollow section column joints using end-plates. Moreover, it expects that the rigidity and resistance of the proposed joint are improved in comparison with the traditional solution (using reverse U channel or special bolts), so the joints could be adopted in seismic resistant moment frames.First, a test program within a RFCS European project titled HSS-SERF “High Strength Steel in Seismic Resistant Building Frames”, 2009–2013, was defined. Within the test program, specimens subjected to significant bending moments (and shear) or to shear only were tested. Then, analytical developments based on the component method approach and aimed at predicting the joint response have been carried out; their validity have been demonstrated through comparisons with the test results.

Floor diaphragms and a truss method for their analysis

Floor diaphragms form a critical component of seismic resistant buildings, but unfortunately, in the main their analysis and design in New Zealand leaves much to be desired. No worse example exists than the CTV Building in Christchurch. Despite the critical importance of diaphragms, there is a paucity of code provisions and design guidance relating to them.
 Using generic examples, the author describes a number of common diaphragm design deficiencies. These include diaphragms where valid load paths do not exist; diaphragms where the floors are not properly connected to the lateral load resisting elements, diaphragms that lack adequate flexural capacity and where re-entrant corners are not properly accounted for, and transfer diaphragms into which the reactions from the walls above cannot be properly introduced or transmitted.
 Three main types of seismic diaphragm action are discussed – ‘inertial,’ ‘transfer’ and ‘compatibility.’ These are, respectively, the direct inertial load on a floor that must be carried back to the lateral load resisting elements, the transfer forces that occur when major changes in floor area and lateral load resisting structure occur between storeys, and the compatibility forces that must exist to force compatible displacements between incompatible elements, such as shear walls or braced frames and moment frames, or as a result of redistribution.
 The author presents a simple Truss Method that allows complex diaphragms to be analysed for multiple load cases, providing accurate force distributions without the multiple models that conventional strut and tie methods would require. Being a type of strut and tie method, the Truss Method is compliant with requirements in NZS3101:2006 [1] to use strut and tie models for the analysis and design of certain aspects of diaphragm behaviour.

Application of near surface mounted (NSM) strengthening technique to traditional timber frame walls

Timber frame buildings are well known as an efficient seismic resistant structure popular all over the world not only due to their seismic performance, but also to their low cost and the strength they offer. These constructions still exist today and it is important to be able to preserve them, so a better knowledge on their behaviour is sought. Furthermore, historic technologies could be used even in modern constructions to build seismic resistant buildings using more natural materials with lesser costs.A great rehabilitation effort is being carried out on this type of buildings, as their neglect has led to decay or their change in use and alterations to the structure has led to the need to retrofit such buildings; only recently studies on their behaviour have become available and only a few of them address the issue of possible strengthening techniques for this kind of walls.In this scope, an innovative retrofitting technique (near surface mounted steel flat bars) is proposed and validated on traditional timber frame walls based on an extensive experimental program. The results of the static cyclic tests on distinct wall typologies retrofitted with the NSM technique are herein presented and discussed in detail. The main features on deformation, lateral stiffness, lateral resistance and seismic performance indexes are analysed.

High strength steel in seismic resistant building frames

AbstractSeismic resistant building frames designed as dissipative structures, must allow for plastic deformations to develop in specific members, whose behaviour is expected to be predicted and controlled by proper calculation and detailing. Members designed to remain elastic during earthquake, such as columns, are characterized by high strength demands. Dual‐steel structural systems, optimized according to a Performance Based Design (PBD) philosophy, in which High Strength Steel (HSS) is used in predominantly “elastic” members, while Mild Carbon Steel (MCS) is used in dissipative members, can be very reliable and cost efficient. Because present seismic design codes do not cover this specific configuration, an extensive European research project [1], HSS‐SERF − High Strength Steel in Seismic Resistant Building Frames, was carried out with the aim to investigate and evaluate the seismic performance of dual‐steel building frames. On this purpose, and based on a large numerical and experimental program, the following objectives have been focused into the project:1. to find reliable structural typologies and joint/connection detailing for dual‐steel building frames, (e. g. of HSS and MCS members), and to validate them by tests and advanced numerical simulations,2. to develop design criteria and performance based design methodology for dual‐steel structures using high strength steel,3. to recommend relevant design parameters (i. e. behaviour factor q, overstrength factor Ω) to be implemented in further versions of the seismic design code, EN 1998‐1 [1], in order to apply capacity design approach for dual‐steel framing typologies,4. to evaluate technical and economic benefit of dual‐steel approach involving HSS.

Hammer head beam solution for beam-to-column joints in seismic resistant building frames

This paper presents a research on an innovative stiffened extended end-plate joint, used to connect I-shaped beams to partially-encased composite wide flange columns. In the joint, T-shaped hammer heads cut from the same I-profiles than the beams are used, instead of using traditional haunches. At the joint level, the column web is strengthened by two lateral plates welded to the column flanges; these plates also reinforce the column flanges. This type of joint is proposed to use in the seismic resistance building frames, as a full-strength and a fully-rigid joint solution. Firstly, a test program carried out within a RFCS European project titled HSS-SERF “High Strength Steel in Seismic Resistant Building Frames”, 2009–2013, will be presented. Then, analytical developments based on the component approach and aimed at predicting the joint response will be described; their validity will be demonstrated through comparisons with the tests. Moreover, a new design concept for full strength joint accounting for the actual position of the plastic hinge and the possible individual over-strength factors for each component is proposed, respecting the requirements of EN1998-1-1.

Seismic behaviour of traditional timber frame walls: experimental results on unreinforced walls

Timber frame buildings are well known as an efficient seismic resistant structure and they are used worldwide. Moreover, they have been specifically adopted in codes and regulations during the XVIII and XIX centuries in the Mediterranean area. These structures generally consist of exterior masonry walls with timber elements embedded which tie the walls together and internal walls which have a timber frame with masonry infill and act as shear walls. In order to preserve these structures which characterize many cities in the world it is important to better understand their behaviour under seismic actions. Furthermore, historic technologies could be used even in modern constructions to build seismic resistant buildings using more natural materials with lesser costs. Generally, different types of infill could be applied to timber frame walls depending on the country, among which brick masonry, rubble masonry, hay and mud. The focus of this paper is to study the seismic behaviour of the walls considering different types of infill, specifically: masonry infill, lath and plaster and timber frame with no infill. Static cyclic tests have been performed on unreinforced timber frame walls in order to study their seismic capacity in terms of strength, stiffness, ductility and energy dissipation. The tests showed how in the unreinforced condition, the infill is able to guarantee a greater stiffness, ductility and ultimate capacity of the wall.

Cyclic response of hollow and concrete-filled circular hollow section braces

The behaviour of seismic-resistant buildings relies heavily upon the inclusion of energy dissipating devices. For concentrically-braced frames, this function is accomplished by diagonal bracing members whose performance depends upon both cross-sectional properties and global slenderness. Traditionally preferred rectangular hollow sections are susceptible to local buckling, particularly in cold-formed tubes, owing to the residual stresses from manufacture. This paper explores the response of hollow and concrete-filled circular tubes under cyclic axial loading. The uniformity of the circular cross-section provides superior structural efficiency over rectangular sections and can be further optimised by the inclusion of concrete infill. A series of experiments was conducted on filled and hollow specimens to assess the merit of the composite section. Comparisons were drawn between hot-finished and cold-formed sections to establish the influence of fabrication on member performance. Two specimen lengths were utilised to assess the influence of non-dimensional slenderness. Parameters such as ductility, energy dissipation, tensile strength and compressive resistance are presented and compared with design codes and empirically derived predictions.

A new modular buckling restrained brace for seismic resistant buildings

This paper proposes an innovative BRB as a new energy dissipation device for earthquake resistant buildings. Its steel yielding core is modular, and this very design enables the yielding force and plastic deformation to be adjusted according to building requirements. Based on connecting several Seriated Modules, which are comprised of any constant number of Shear Basic Dissipation Units, deformation is proportional to the number of Seriated Modules and force to the number of Shear Basic Dissipation Units (on the Seriated Modules). Assembling the brace consists of sliding the greased yielding core into the restraining unit and coupling it with pins, thus providing easy inspection or replacement of the dissipation unit if required. Fully-scaled prototypes have been tested under reversal cyclic displacements and the hysteretic response has been proved stable and with a high cumulative ductility. The main parameters are the yielding force and the yielding displacement; which can be predicted with simple expressions. A methodology to design a restraining unit able to tackle of buckling by taking into account the initial sway deformation and the functional gap between the yielding core and the restraining unit is proposed. The hysteretic behavior has been simulated with conventional FEM software.

Earthquakes – A Historical Review, Environmental and Health Effects, and Health Care Measures

Earthquakes are natural disasters that can occur at any time, regardless of the location. Their frequency is higher in the Circum-Pacific and Mediterranean/Trans-Asian seismic belt. A number of sophisticated methods define their magnitude using the Richter scale and intensity using the Mercani-Cancani-Sieberg scale. Recorded data show a number of devastating earthquakes that have killed many people and changed the environment dramatically. Croatia is located in a seismically active area, which has endured a series of historical earthquakes, among which several occurred in the Zagreb area. The consequences of an earthquake depend mostly on the population density and seismic resistance of buildings in the affected area. Environmental consequences often include air, water, and soil pollution. The effects of this kind of pollution can have long-term health effects. The most dramatic health consequences result from the demolition of buildings. Therefore, quick and efficient aid depends on well-organized health professionals as well as on the readiness of the civil defence, fire department, and Mountain Rescue Service members. Good coordination among these services can save many lives Public health interventions must include effective control measures in the environment as secondary prevention methods for health problems caused by unfavourable environmental factors. The identification and control of long-term hazards can reduce chronic health effects. The reduction of earthquake-induced damages includes setting priorities in building seismically safe buildings.

Parameterization and Evaluation of Seismic Resistance within the Context of Architectural Design

This paper explores and discusses the possible relations between the architecture and seismic resistance of buildings. The first part of the paper stresses the practical importance of earthquake resistance in every building built in earthquake prone areas. Further on it is shown that the earthquake resistance in architectural expression can be dealt in hidden or concealed principles or on the other hand in revealed or emphasized ways. The paper hypothesize that the architectural design, which to a certain level reflects an earthquake threat, might provide a better designs with stronger architectural identity for buildings in earthquake-prone areas. In this context it summarizes the term “earthquake architecture”, which is defined as particular approach to design of buildings in architecture in a way which draws the inspiration from earthquake engineering. Such an approach might be one of the best responses of the architects (in cooperation with structural engineers and earthquake specialists) to the earthquake threats. In the second part of the paper the proposed method for recognition and evaluation of architecture in the context of earthquake resistance is presented. Using this evaluation method, it is possible to classify buildings at several different levels of “earthquake architecture”. Case study of three comparable competition projects is presented as example of using this method to evaluate the architectural design in the context of seismic resistance, and at the same time, to indicate the ways in which architecture can play its role part within earthquake resistant design.

Effects of loading conditions on the behavior of unbonded post-tensioning strand-anchorage systems

Since the 1990s, new types of seismic-resistant building and bridge structural systems have been designed that use unbounded post-tensioning tendons. The entire post-tensioning force is transferred at the tendon anchorages in these structures. This experimental study investigates the use of unbounded post-tensioning strand-anchorage systems subjected to different loading conditions. The experiments investigate the strand stresses and strains at wire fracture inside the anchors, considering initial stress, loading rate, eccentricity between the strand ends, and post-yield cyclic loading. Results showed that post-yield cyclic loading is the parameter that most consistently reduces the average wire fracture strains of strand-anchorage systems and should be used in the validation testing of unbonded post-tensioning strand-anchorage systems for extreme seismic applications. Updated stress-strain relationships are proposed for 0.5-in.-diameter and 0.6-in.-diameter strands that provide a separate stress-strain relationship for each diameter as well as a combined one for both diameters. Directions for future research are discussed.

Earthquake characteristics and building damage in high-intensity areas of Wenchuan earthquake II: Dujiangyan and Pengzhou City

On May 12, 2008, a massive earthquake occurred along the Longmen Mountain Central Fault in Sichuan Province, China, causing serious damages to buildings near the fault. As the Longmen Mountain Central Fault and the Anterior Fault both traversed Dujiangyan and Pengzhou cities, the seismic intensity in these areas reached levels IX–XI. Therefore, these two cities were among the most seriously damaged regions. In this article, the types of damage to buildings in the two cities and their affiliated towns or villages are investigated and reported. It is found that the damage to a building is related to its structure type, distance from the faults, and so on. The results provide valuable information on the seismic resistance of buildings in similar areas.

Response of earthquake-resistant reinforced-concrete buildings to blast loadingThis article is one of a selection of papers published in the Special Issue on Blast Engineering.

Recent bomb attacks on buildings have raised awareness about the vulnerability of structures to blast effects. The resiliency of structures against blast-induced impulsive loads is affected by structural characteristics that are also important for seismic resistance. Deformability and continuity of structural elements, strength, stiffness, and stability of the structural framing system and resistance to progressive collapse are factors that play important roles on the survivability of buildings under both blast and seismic loads. The significance of these structural parameters on blast resistance of reinforced concrete buildings is assessed through structural analysis. Both local element performance and global structural response are considered while also assessing the progressive collapse potential. The buildings under investigation include 10-storey moment resisting frames with or without shear walls. The blast loads selected consist of different charge-weight and standoff distance combinations. The results are presented in terms of ductility and drift demands. They indicate improved performance of seismic-resistant buildings when subjected to blast loads, in terms of local column performance, overall structural response, and progressive collapse potential.

EVALUATION OF PERFORMANCE OF ASYMMETRICALLY DUAL SYSTEM STRUCTURES USING PUSHOVER AND TIME HISTORY ANALYSES

Performance-based design is becoming increasingly popular in designing a seismic resistant building. In the study, a twelvestory, reinforced concrete office building with asymmetric configuration using dual system located in seismic zone 6 was designed conforming to the Indone sian S e i smi c Code SNI 03-1726-2002 and the Indonesian Concrete Building Code SNI 03-2847-2002. The seismic performance of the building was evaluated using the Static Nonlinear (Pushover) Analysis and Inelastic Dynamic Time History Analysis. The performance point obtained from the pushover analysis was defined using various methods, such as FEMA 356, ATC-40, FEMA 440, and SNI 03-1726-2002. The result of the study indicated that the highest performance point was that obtained according to FEMA 356 and FEMA 440, whereas the lowest value was that in accordance with SNI-03-1726-2002. The roof displacement difference of that obtained from El-Centro dynamic analysis and performance-point pushover analysis can reach up to 5 cm and 2.4 cm in X- and Y-directions, respectively. This indicates that the pushover analysis is quite accurate for evaluating the corresponding building since the first mode shape is quite dominant.