Inelastic Drift Research Articles

ANALISIS KINERJA STRUKTUR PADA GEDUNG BERTINGKAT DENGAN ANALISIS PUSHOVER BERDASARKAN ATC-40

Indonesia is an area prone to earthquakes. Earthquakes can cause infrastructure damage and casualties. Efforts are needed to reduce the risk of earthquake hazards by strengthening earthquake-resistant infrastructure. The design procedures for earthquake-resistant buildings are carried out using a performance-based design approach. Building performance can be estimated through non-linear static pushover analysis. This research takes a case study in Jongke Market, Surakarta. This research aims to determine the capacity curve, performance level, and structure collapse mechanism. The method used is pushover analysis with the capacity spectrum. The result of this analysis is a capacity curve that processed to determine the level of structure performance referring to the drift ratio limitation table in the Applied Technology Council (ATC-40). Based on the results of this research, displacement that occurred in the x direction is 92 mm and in the y direction is 77 mm. Building displacement is good because the displacement that occurred is smaller than the displacement limit (control). The total maximum drift in the x direction is 0.007 and in the y direction is 0.006. The maximum inelastic total drift in the x direction is 0.005 and in the y direction is 0.004. Based on the drift ratio limitation table in the ATC-40 document, this building has an immediate occupancy performance level. Based on the plastic hinge mechanism formed, the existing structure also meets the ideal collapse concept (strong column-weak beam).

Analysis of Base Shear and Story Drift in the Low-Rise RC Sructure

<p class="Abstract">Earthquakes frequently occur in Indonesia because it is an earthquake-prone area. Due to lateral load from an earthquake can cause a weakly constructed building to collapse. Designers often only consider tall buildings in designing earthquake-resistant building structures but ignore earthquake-resistant designing for low-rise buildings. This study focuses on the analysis of earthquake resistant structures with a case study of low-rise buildings in the form of a 3-story reinforced concrete (RC) building in the South Jakarta area. The objective of the study is to analyze the base shear and story drift of the structure due to lateral or earthquake loads. The structure is a reinforced concrete with the concrete compressive strength of <em> </em>= 30 MPa and longitudinal reinforcement of = 420 MPa and stirrups of = 280 MPa. This study uses equivalent static analysis manually and using ETABS 20.1.0 application. The results showed that three story buildings analyzed using equivalent static analysis method and using ETABS 20.1.0 application had almost the same results on horizontal forces with manual result of 1680.97 kN and ETABS of 1648.46 kN. The elastic story deflection and inelastic story drift in this study are still within safe limits because it is below the drift limit.</p>

PERENCANAAN ULANG STRUKTUR GEDUNG LIMA LANTAI ASRAMA HAJI SEMARANG

Due to the increasing number of Hajj pilgrims, the need for accommodating them has also risen. Therefore, a redesign is necessary to enhance the capacity of accommodating the pilgrims. The Analysis and Structural Planning of the Hajj Dormitory Semarang using ETABS software in compliance with the Indonesian National Standard (SNI). The redesign of the Hajj dormitory aims to augment the housing capacity for prospective Hajj pilgrims. The Revised Structural Planning for the Five-Story Hajj Dormitory Building Semarang aims to analyze and redesign the structure of the dormitory. This involves utilizing concrete quality of 24.9 MPa for the upper structure and 30 MPa for the lower structure, with main reinforcement using 420 MPa, while secondary reinforcement uses 280 MPa. The structural analysis approach involves inputting geometric data, loads, and material characteristics, including desired concrete and steel qualities, into the ETABS software. The analysis adheres to the SNI guidelines governing building loads, seismic resilience, and other structural safety factors. The analysis results provide insight into the structural response spectrum, with a mass participation of UX 99.98% and UY 99.19%. Control Base Shear Vdynamic > Vstatic, with Eq Dx > Eq Sx and Eq Dy > Eq Sy, is 8623.266 > 8563.3067 and 7928.0409 > 7722.4166. The maximum story displacement due to dynamic seismic motion in the X and Y directions is 14.33 mm and 15.95 mm. Meanwhile, the story drift with an Inelastic Drift value less than 61.5 mm for safety building permissible deviation. The largest permissible deviations obtained for the X and Y directions are 18.816 mm and 20.554 mm.

Test study on performance of U80 standardized glass curtain wall system

In order to study the air infiltration performance, water penetration performance, structural performance under wind pressure and seismic inter-story drift performance of U80 standardized glass curtain wall system, one full size test specimen was designed according to the actual engineering situation. The test specimen was composed of six-unit curtain walls with exposed frames and six-unit curtain walls with concealed frames. According to the specification of United Stated, the various performance of the test specimen was investigated. The results show that the rate of air leakage of the specimen is within allowable values under design pressure. No water leakage is observed when the water penetration tests with static and dynamic pressure tests. During the structural performance tests at 100% design wind pressure, the deflections of framing members as well as glass panels are all within the allowable deflection limits. No breakage is observed under the 150% design wind pressure. Permanent deformations of framing members remain less than 0.1% of clear span. After 3 cycles of elastic and inelastic inter-story drift performance tests, no damage is observed. The U80 standardized glass curtain wall system has great air infiltration performance, water penetration performance, structural performance and seismic inter-story drift performance. And it can be used in the practical engineering.

Discussion: Design for Local Member Shear at Brace and Diagonal-Member Connections: Full-Height and Chevron Gusset

The paper “Design for Local Member Shear at Brace and Diagonal-Member Connections: Full-Height and Chevron Gusset” (Sabelli and Saxey, 2021) develops equations for checking local member shear demands using a Concentrated Stress Method (CSM) and presents a design example. This discussion presents results from a finite element (FE) model, based on the design example in the paper, to quantify the accuracy of the proposed design equations in predicting beam yielding. The FE model confirmed that the beam yielding state would not have occurred for the example frame under the design forces but would have occurred for forces about 4% higher. The stress and strain distributions observed in the FE model were consistent with those assumed in the CSM, although two points for potential refinement were noted. If beam yielding in a concentrically braced frame is forced, through oversized braces, the plastic mechanism would be like an eccentrically braced frame (EBF) but with higher yield force, and higher beam inelastic rotations and strains for the same inelastic story drift.

Computational analysis of structure manufactured by means of the steel framing system. Case study: industrial warehouse

A study is carried out between the traditional system of industrial warehouse construction, which is characterized using hot-rolled steel profiles, in comparison with the Steel Framing system, which uses low-thickness cold-formed steel profiles. Although the low-thickness profiles used in Steel Framing may generate mistrust, these profiles work by shape and not by mass. Steel Framing being a modern system, in our region it is not easy to find industrial warehouse constructed with low-thickness cold-formed steel profiles for the main and secondary elements, so this study not only focuses on the constructive aspects, but also contributes to understand the physical response of the Steel Framing system to different loads. Between the two mentioned systems, the seismic-resistant design of the industrial structure is also included to first check if it is possible to use the Steel Framing system in medium industrial warehouse, located in highly seismic areas, such as the coastal region of Ecuador. It has been proven that the Steel Framing system is resistant to high winds, earthquakes and other loads that are established in national and international regulations, and we proved that taking advantage of the effective properties of cold-formed profiles increases their resistance The results of drifts demonstrate the seismic resistance of the system, with the value of 0.00107 being the maximum value of inelastic drift obtained in the X direction, which represents only 5.37% of the value allowed in the standard.

Seismic Performance of Reinforced Concrete Beams Susceptible to Single-Crack Plastic Hinge Behavior

Following the 2010/2011 Canterbury and 2016 Kaikoura earthquakes, a number of reinforced concrete (RC) beams in high-rise structures developed a single primary crack at the beam-column interface without the formation of distributed secondary cracks along the beam length. Detailed assessments showed that these beams have conforming longitudinal steel ratios and the single-crack mechanism may be due to design and/or construction practices for beam-column joints in the 1980s. In order to investigate the seismic behavior of reinforced concrete beams with detailing that inhibited the spread of flexural yielding, an experimental program was carried out on RC beam specimens, having similar reinforcement detailing to that of beams that developed a single crack at their ends during the Kaikoura earthquake to understand their seismic behavior, postearthquake repairability, and residual low-cycle fatigue life. Experimental results showed that the beams were able to undergo significant inelastic drift demands without loss of lateral resistance and have sufficient residual drift capacity following moderate and large earthquake demands. The response of the beam specimens was dominated by hinge rotation via the bond-slip mechanism. Comparisons showed that the measured drift capacities of the beams exceeded the predicted drift capacities computed using state-of-the-practice procedures.

Flexure‐axial‐shear interaction of ductile beams with single‐crack plastic hinge behaviour

AbstractOne of the key damage observations in modern reinforced concrete (RC) frame buildings, damaged following the 2010/2011 Canterbury and 2016 Kaikoura earthquakes, was localised cracking at the beam‐column interface of capacity‐designed beams. The localised cracking in the beams was due to curtailed longitudinal bars at the beam‐column interface. Following these observations, without experimental data to justify desirable seismic performance, modern beams controlled by localised cracking were assumed to be potentially earthquake‐vulnerable. To address this, an experimental program was carried out on six RC beam specimens susceptible to single‐crack plastic hinge behaviour due to curtailed longitudinal bars. The experimental data show that RC beams with single‐crack plastic hinge behaviour can undergo significant inelastic drift demands without loss of lateral resistance. However, contrary to conventional beams with distributed cracking, the response of RC beams with single‐crack plastic hinge behaviour due to curtailed longitudinal bars is mainly dominated by hinge rotation (via bond‐slip) and shear sliding at the column face. The current paper studies the interdependence of axial elongation, bond‐slip and shear sliding deformation of RC beams with single‐crack plastic hinge behaviour under cyclic demands. A procedure for seismic assessment of RC beams with single‐crack plastic hinge behaviour due to curtailed longitudinal bars is proposed. The proposed formulations can be adopted to develop adequate numerical models for simulating the response of RC frames with beams susceptible to single‐crack plastic hinge behaviour due to curtailed longitudinal bars.

Verification of seismic enforced-displacement pushover procedure on torsionally flexible, asymmetric, multi-storey r/c buildings

A recently proposed direct Displacement-based procedure of nonlinear static (pushover) analysis on multi-storey reinforced concrete (r/c) buildings is verified here against the results of Nonlinear Response History Analysis. An asymmetric, regular in elevation, torsionally flexible, multi-storey r/c building designed according to Eurocode EN 1998 is investigated. Taking fully into account the inelastic torsion and the higher mode effects, as well as the P-Delta effects, the proposed procedure applies a pattern of seismic floor enforced-displacements along on the “Capable Near Collapse Principal Axes of the building”, aiming at Near Collapse state.  The envelope of the results of sixteen final non-linear static analyses on the investigated building shows that the main aspects of the spatial seismic action effects can be safely captured by the proposed procedure, especially regarding the inelastic interstorey drift ratios, as well as the plastic mechanism of the building.

A detachable configuration for the precast beam-column connection using metallic damper as connector: Experimental investigation

A beam-column connection with satisfactory seismic performance and assembly efficiency is preferred in prefabricated structures. An evolved detachable configuration for the precast beam-column connection using metallic damper as connector (PCF-MDC-nuts) is proposed. The detachable connection significantly reduces the labor cost of building demolition, repair, and recycling. A specimen PCF-MDC-nuts was designed and constructed based on a precast “wet” connection (specimen PC)). A dog-bone damper was adopted in PCF-MDC-nuts as a sacrificial element. First, a laboratory test was performed on the damper, followed by the beam-column connection. The dominant failure pattern of the dog-bone damper, both in the damper and connection tests, was mainly out-of-plane flexural-torsional buckling. The test results show that PCF-MDC-nuts has a similar flexural strength as PC. The maximum in-elastic drift ratio of PCF-MDC-nuts has been improved to 5.48% compared to that of PC (3.27%). The degradation of PC-MDC-nuts was alleviated compared with PC. The cumulated absorbed energy and maximum equivalent viscous damping ratio of the PCF-MDC-nuts were 41.04 kN·m and 44.17%, respectively, while those of PC were 11.06 kN·m and 19.48%. The seismic performance of PCF-MDC-nuts was superior to PC. The concept of the proposed detachable configuration was justified.

Seismic performance evaluation of masonry infill R.C. frame considering soil-structure interaction

The structural damage due to recent seismic events in Nepal has led to a dire need for studies considering soil-structure interaction (SSI) as the majority of designers still adopt conventional design principles. These damages may be the result of the conventional fixed base method’s failure to take into account the underlying soil properties. Post $$M_w$$ 7.8 Gorkha earthquake, revised Nepal National Building code NNBC 105:2020 has classified soil types based on the rigidity of the soil. A comparative analysis is carried out using linear-static and nonlinear static (Pushover) analysis considering the fixed and flexible base of a masonry infill RC frame. The seismic performance parameter evaluated for a target inelastic drift of 2% are in terms of their fundamental time period, peak floor displacement, inter-storey drift ratio (IDR), ultimate load carrying capacity and yield mechanism. The consideration of SSI drastically influenced the fundamental time period, peak floor displacement and IDR with decreasing rigidity of soil. The fixed base structure exhibited a higher ultimate load-carrying capacity than the flexible base structure for all soil types. The masonry infill dissipated the seismic energy by the failure of the majority of struts. Furthermore, the post-yield behaviour of all models highlighted that the damage level of RC frame and masonry infill elements were higher for fixed base.

Regression models for predicting the inelastic seismic response of steel braced frames

This paper describes the development of regression equations to predict the peak inelastic drift and acceleration response of steel concentrically braced frame (CBF) building structures. A database of Engineering Demand Parameters (EDPs) is developed by performing a large number of nonlinear time-history analysis (NLTHAs) in OpenSEES for a set of 24 case study CBFs. A consistent and realistic set of mechanical models is achieved by designing each case study frame using Eurocode 8. Multi-variable regression models for peak drift and acceleration response at each storey level are fitted to the NLTHA results data. A nonlinear formulation and robust regression are employed to capture the influences of the Eurocode 8 behaviour factor and brace slenderness and overstrength limits on the EDP profiles over the height of a building. Comparison with existing models shows that the fitted regression equations achieve improved agreement with NLTHA results across a wide range of structural parameters. The regression models can be applied in performance-based design or assessment to predict the peak inelastic response of CBF structures without performing additional nonlinear analyses.

A drift-based design procedure for RC buildings considering the effect of shear wall-floor slabs junction

Reinforced Concrete (RC) structural wall is widely used in the lateral force resisting system for multistoried RC frame buildings located in earthquake-prone regions. In such buildings, the wall is connected to the RC slab at every floor level. The junction region of shear wall and floor slab constitutes an important link in the load path from slab to wall during earthquake shaking, thereby influencing the pattern of lateral load distribution in the shear wall. In case of multistoried building, the maximum elastic drift is estimated by carrying out linear static analysis for different load combinations as recommended by the Indian Earthquake Code IS 1893 (Part 1): 2016. However, during strong earthquake shaking, the inelastic lateral drift needs to be monitored to avoid undesirable levels of damage in structural members. The inelastic drift level of an isolated slender shear wall considering the behaviour of wall-slab junction has not been studied in the past. The present study aims to investigate the possible lateral drift limit of RC wall frame building considering the effect of floor slabs.

EVALUATION OF STRUCTURAL PERFORMANCE OF INSTALLATION BUILDING AND INPATIENT WARD IN DISTRICT HOSPITAL OF WATES USING SOFTWARE SAP-2000

This District Hospital of Wates was developed and constructed to meet medical need for local people of Kulon Progo District and this hospital was expected to have impact on the public economy wheel improvement. This hospital has a reinforced concrete structure to support the standing torque with five floors in 4.5-m height of each floor and has 20.5-m height. The building structure must be able to support earthquake force at specific level without significant damage of structure or, if the building must fail. The objective of this study was to find performance point value of the building, ratio drift value based on ATC-40 and performance level. This study evaluated the building performance of the hospital based on spectrum response and national standard of Indonesia. The results of study indicate that Performance Point value with X-direction slide force was 3188.541 kN and Y-direction was 1058.513. On the other hand, ratio drift value, based on ATC-40, had maximum in-elastic drift of X-direction = 0.000000249 and maximum In-elastic drift of Y-direction = 0.000000405, it means that the reviewed building was included in level of Immediate Occupancy (IO) so that the building of hospital, when earthquake faced it, did not experience structural and non-structural damage; therefore, this building remained safe. Keywords : Pushover, Perfomance Point , Ratio Drift, ATC-40

Evaluation of deflection amplification factor for steel buckling restrained braced frames

In the common force-based design method prescribed in seismic codes, displacements of a structure under reduced seismic forces are amplified by a deflection amplification factor, Cd, to estimate inelastic displacements. The present study evaluates Cd for steel buckling restrained braced frames (BRBFs). For this purpose, six low-to mid-rise structures comprising 2- to 12-story BRBFs are considered, and nonlinear dynamic analyses are performed. Results indicate that the recommended Cd by ASCE 7 (i.e., Cd = 5.0) underestimates the inelastic maximum interstory drift ratio (IMIDR) of lower stories in BRBFs under the design earthquake. Furthermore, estimation of IMIDR in upper stories of mid-rise structures using Cd = 5.0 leads to acceptable results. Therefore, by applying the particle swarm optimization (PSO) algorithm, a new equation is proposed for Cd to more realistically estimate IMIDR in steel BRBFs under the design earthquake. In the case of roof displacement, the results show that for low-rise structures the recommended value of Cd = 5.0 significantly underestimates the inelastic maximum roof drift ratio (IMRDR). On the other hand, for taller structures Cd = 5.0 overestimates the IMRDR. Thus, another new equation is proposed using the PSO algorithm for CdRoof in order to better estimate the IMRDR. Moreover, effects of variation in strain hardening ratio on Cd and CdRoof are investigated. In the last part of this study, variations of the ratios of Cd and CdRoof to response modification coefficient (R) with ductility reduction factor (Rμ) are investigated.

Seismic performance of reinforced concrete structures with pushover analysis

A building that looks strong enough might possibly collapse due to the earthquake load. Earthquake resistant design is generally based on an analysis of elastic structures that are given a load factor to simulate ultimate conditions. When an earthquake occurs, the collapse behavior of a building structure is inelastic. Evaluations that can estimate the inelastic condition of buildings during an earthquake are analyzed using pushover analysis. Pushover analysis is the nonlinear static load of the structural collapse behavior of an earthquake, while the performance point is the magnitude of the maximum displacement of the structure during a earthquake. The inelastic structure analysis and evaluation method used computer application SAP 2000. Evaluation results of structural performance levels according to Applied Technology Council 40 (ATC-40) on the X and Y direction structure, the maximum total drift and total inelastic drift maximum values in the X and Y directions included in the Immediate Occupancy (IO) level category (maximum drift value of a building structure 0.00047 < 0.005).

Energy based Design as an Alternative Intuitive Criterion to the Drift Criterion

Structural integrity with smaller structural plan density is doubtful under earthquake loading, while the structure is supposed to undergo inelastic deformation. Recent past damages under moderate earthquakes have raised a lot of questionnaires to the existing seismic design procedures. Drift controlled damage indices are consistently under reappraisal because of our better understanding of dynamic loading. Hence, energy based concept is suggested in an effort to explicate the response of building systems during earthquake loading. In this paper, explicit expressions for various components of energy i.e. strain, kinetic, damping and inelastic energy versus drift have been derived and discussed with the post processing results of building systems under varying strong earthquake motions. The incremental dynamic analysis is used in our study and the results show that the energy criterion analysis gives better one than the drift criterion for the structures subjected to earthquake ground motions.

Cyclic Behavior of Replaceable Shear Fuse Connections for Steel Moment Frames

Most steel moment frames rely on beam yielding to safely handle the inelastic drifts that will be imposed by severe earthquakes. More resilient steel moment frame concepts such as post-tensioned self-centering frames and friction connections have not seen widespread use, perhaps because they deviate dramatically from current practice. Experimental work was performed to investigate the performance of a new moment frame connection called the replaceable shear fuse connection. The replaceable shear fuse connection uses beam flange plates with special cutouts to prevent beam damage. Seven reduced-scale specimens were tested to investigate the effect of fuse geometry on drift capacity, connection strength, and connection stiffness. The specimens achieved maximum drifts of 0.06–0.10 rad without experiencing strength degradation prior to fuse tearing. The shear fuses experienced strain hardening of 1.39–1.75 times yield, similar to high strain hardening that has been observed in shear link testing. The connections had more-than-adequate stiffness to be classified as fully rigid. Full-scale testing should be conducted to evaluate the effects of beam depth, column depth, and fuse parameters.

Estimation of Inelastic Interstorey Drift for OSB/Gypsum Sheathed Cold-Formed Steel Structures under Collapse Level Earthquakes

In order to estimate the inelastic interstorey drift of cold-formed steel (CFS) framed structures under collapse level earthquakes, the deflection amplification factor ηp is employed in this paper to compute the maximum interstorey drift ratio (IDRmax) from an elastic analysis. For this purpose, a series of CFS wall specimens were tested under cyclic horizontal loads, and then the hysteresis model of the walls was put forward by test results. In terms of the hysteresis model, a large quantity of elastic-plastic time-history analysis of CFS building structures was conducted based on the storey shear-type model. Furthermore, the deflection amplification factor ηp for estimating IDRmax and the parameters were analyzed. The results indicate that the deflection amplification factor ηp is highly dependent on yielding coefficient of storey shear force ξy, storey number N, period of structure T, and ground acceleration records GA. Eventually, an approximate ξy-N-ηp relationship for estimating the deflection amplification factor ηp is proposed in this paper, which can be used for seismic design in practices.

IMPACT OF INTRODUCING SEMI-RIGID MOMENT FRAMES ON SEISMIC RESPONSE OF BRACED FRAMES

Maximum seismic inelastic drift demand in a steel building with braced frames as primary seismic-force-resisting (SFR) system tends to concentrate in few stories without considering inherent participation of designed gravity-force-resisting (GFR) system in actual structural stiffness and strength. The influence of GFR system on stiffness and strength can be taken into account by considering the composite action in beam-to-column shear connections that exist in modern steel building construction to form actual semi-rigid moment-resisting frames. Therefore, modeling semi-rigid moment frames as an equivalent to the GFR system in braced frame buildings could be utilized as a representative to the strength provided by gravity frames. This paper presents a seismic evaluation of a six-story chevron braced frame, with and without semi-rigid moment frame. Four different cases are investigated under a set of ground motions and results are discussed in terms of story drift distribution along the height. The results pointed out that the current findings lay a foundation to conduct further investigation on the seismic performance of braced frames as designed SFR system together with GFR system.