Immediate Occupancy Research Articles

The Effect of Columns Configuration on High-rise Building Using Performance-based Design

An important point of seismic assessment is the judgment of performance limit, which is ascertaining safety framework as building life. Because the higher a multi-story building was built, the higher the risk to the earthquake loads will be. In this paper, a description of column configuration in particular performance-based procedures used for assessing of associated tall buildings is proposed because the columns' size and its configuration strongly affect the performance of the seismic structural response. This paper is aimed to determine the column's size and its proper configuration associated for seismic resistance building structures. Five-building types were modeled using various column sizes and configurations. The pushover analysis from SAP2000 was used to obtain deformation capacity. Hence, the capacity spectrum method ATC-40 and displacement coefficient method FEMA 356 were implemented in order to get the performance points of each building model. The performance evaluation results show that all structural models have a level of performance that is better than maximum expectations, which are on the IO (Immediate Occupancy) performance level. Both building structural models C and E provide the largest deformation capacity, which is able to achieve displacement targets of up to 1.6 m. However, the structure's deformation capacity is greatly affected by the column size and portal structure configuration. The capacity curve from pushover analysis shows that the largest deformation capacity is achieved by medium columns size with a target-drift up to 3%.

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

Global Retrofitting Strategies for an Existing Three-storied RC School Building in Mandalay, Myanmar

Low to severe earthquakes occur around the world every year, damaging and causing structural failure in buildings. Consequently, seismic improvements are required for existing buildings that are vulnerable to damage by seismic forces. The objective of this study was to investigate retrofitting strategies in terms of their sustainability. Mandalay, Myanmar, was selected as the study area as it is located near the Sagaing fault, which itself is in a strong earthquake zone (seismic zone 4). A three-storied RC building with a non-seismic design was selected as a case study building. An investigation was carried out into the performance and vulnerability of the building under three earthquake hazard levels. The vulnerability index value was calculated using the Priority Index method. Meanwhile, non-linear static pushover analysis was performed to investigate the performance of the existing building using SAP2000 V14 software. Four different types of retrofitting strategies were considered, namely reinforced concrete shear walls with openings, reinforced concrete shear walls without openings, steel plate shear walls, and finally steel bracing. Among these, it was found that the use of steel plate shear walls was the best retrofitting technique, owing to it having the best performance along with the lowest displacement. Its performance level reached up to the Immediate Occupancy (IO) level even under the conditions of a Maximum Consider Earthquake (MCE).

The performance-based seismic response of special steel MRF: Effects of pulse-like ground motion and foundation safety factor

This study aims to investigate the effect of near-fault pulse-like earthquake ground motions as well as the foundation safety factor, on the performance-based seismic response (PBSR) of special steel moment-resisting frame (MRF). The Beam on the Nonlinear Winkler Foundation (BNWF) approach was employed for modeling the soil-foundation system. In this regard, values of 2, 3, and 5 were considered for the foundation vertical safety factor (FSv). The PBSR of the MRF has been assessed under 32 far-fault (FF) ground motions as well as 55 near-fault (NF) pulse-like records, through Incremental Dynamic Analyses (IDAs). The effects of extracted pulses and residual components of near-fault records were investigated as well. Results show that regardless of the earthquake record type, FSv has no considerable effect on the performance-based drift demand in the structure. However, larger settlement and rotation of the foundation are expected when a small FSv is accounted for. This leads to difficulties in providing the Immediate Occupancy (IO) performance objective for structures with operational performance levels. The effect of the input record type on the median foundation settlement is also inconsiderable. As well, a similarity was observed between the seismic performance of the structure under the residual components and the far-fault records. What’s more, neither the extracted pulses nor the residual components of near-fault earthquake records can represent the original near-fault pulse-like records. Also, the residual component plays an important role in the structural responses under low-intensity earthquake events.

Seismic reliability assessment of RC tunnel-form structures with geometric irregularities using a combined system approach

Tunnel-form structures represent a new type of structural systems with enhanced earthquake resistance and considerably reduced construction times, if compared to conventional reinforced concrete frames and dual systems. Due to the limited information about the seismic performance of tunnel-form buildings in the presence of vertical and horizontal irregularities, seismic design standards generally prevent such irregularities and therefore impose significant architectural limitations. To address this issue, a liability assessment is here conducted on irregular 5- and 10-storey tunnel-form buildings subjected to 12 different earthquakes, representing a design spectrum. The structural response of these buildings is obtained under both Design Basis Earthquake (DBE) and Maximum Considered Earthquake (MCE) hazard levels by using time-history and nonlinear static (pushover) analyses. The reliability of the buildings is then assessed by using a novel combined system approach, in which the structural effects of walls and coupling beams at each storey are modeled as series and parallel sub-systems. The results of this study show that, despite the geometric irregularities, all the structural elements could satisfy the Immediate Occupancy (IO) performance level under both DBE and MCE scenarios with over 95% reliability. Therefore, enforcing the regularity for tunnel-form structures in current seismic design guidelines appears to be too conservative; the results of this study can then prove useful for a more efficient design of irregular tunnel-form structures in seismic regions.

Effects of Brace Configuration and Structure Height on Seismic Performance of BRBFs Based on the Collapse Fragility Analysis

The brace configuration and structure height are two factors that have a significant effect on the seismic behavior of braced frame buildings. In the present study, the buckling-restrained braced (BRB) frames were considered to estimate the effect of these two parameters using probabilistic seismic assessment methods. The uncertainty in the different parameters involved in the seismic design of the structural system was also considered. Four, six, and ten-story buildings with the Chevron and inverted Chevron bracing configurations were designed, and their responses due to various ground motions were estimated using incremental nonlinear dynamic analyses. Fragility curves, mean annual frequency of exceeding immediate occupancy (IO), and collapse prevention (CP) states were generated using probabilistic seismic analysis, fragility curves concept, and drift hazard curves. The results demonstrate that the inverted Chevron type BRBFs has better structural performance than Chevron bracing types. Furthermore, an increase of the height of structures, despite lower drift’s hazards, increases the fragility probability.

Assessment of the seismic safety of school buildings in Mexico: A first look

For the first time in Mexico, a comprehensive data gathering and analysis project on the seismic performance of school buildings in the aftermath of the 2017 earthquakes was developed. Aimed at supporting the planning and decision-making of the Mexican government’s reconstruction program, school performance was observed and measured in the field. To further evaluate building performance, numerical modeling of archetypical buildings was carried out. Calculated performance was consistent with observed structural damage. Numerical analysis indicated that pre-1985 masonry and concrete buildings are more likely to exhibit damage that could compromise the structural stability. In contrast, recent structures are very likely to attain the immediate occupancy (IO) performance level that is implicitly assumed in school design. Studies indicated that rehabilitated school buildings through wall jacketing in masonry buildings and by adding new concrete shear walls and masonry infills to concrete structures are likely to comply with IO. From the lessons learned, policy, technical, implementation, and sustainability and outreach recommendations are proposed to implement a multiannual, systematic, incremental, and integral strategy for reducing earthquake risk of school buildings in Mexico.

Seismic fragility curves of steel structure industrial building using IDA method

Recent natural disaster events have caused damage to structures and led to loss of lives. Steel structure industrial building is one of the important structures that needs to be examined as these structures can have huge impact on the surrounding areas. Therefore, this study presents the fragility curves and performance curves of steel structure industrial building under earthquake loading. The structure consisted of beam, column, and bracing were modelled using three dimensional finite element modelling. The fragility curves were obtained for the structure, and the performance curves were developed based on lateral load, which was affected by the geometry of the building. Three records of far-field ground motion and three records of local ground motion were used for incremental dynamic analysis (IDA). The five levels of performance stated by FEMA-273, namely, operational phase (OP), immediate occupancy (IO), damage control (DC), life safety (LS), and collapse prevention (CP) were used as main guidelines to evaluate the structural performance. Results showed that, probability damage for operational phase, OP started at 0.19g and 5% of the structure analysed are expected to have immediate occupancy IO, indicating minor cracks to the structure at 0.4g PGA. Moreover, the performance response of the structure to the earthquake was obtained from the study.

Performance-based seismic assessment of precast ferrocement walls for one and two-storey housing

In recent years, innovative structural systems based on Precast Ferrocement Walls (PFW) have been proposed for one and two-storey housing so as to lessen the housing deficiency. This article presents the results drawn from cycling loading tests carried out over two types of PFWs, in order to determine their strength, hysteretic behavior, ductility, energy dissipation capacity, equivalent viscous damping, and damage limit states. These walls have similar structural systems that differ only in the type of reinforcement. To assess their seismic performances for two earthquake hazard levels, a nonlinear dynamic analysis methodology based on the Performance-Based Seismic Design philosophy was developed, which uses the Mostaghel’s multilinear hysteretic model to simulate accurately the actual inelastic behavior and energy dissipation capacity of the PFWs, together with the incremental dynamic analysis (IDA) technique. The Immediate Occupancy (IO), Life Safety (LS), and Collapse Prevention (CP) structural performance levels were considered and related to the damage limit states. Finally, the performance points of both PFWs fell within the IO range with a 100% probability of incurring no structural damage state for both earthquake hazard levels, which demonstrates their good seismic performance.

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).

The performance of structures with circular columns and square columns in the structure of Rancacili Silinder II building

In general, structural planning is only limited to count the safety and durability of the building in holding and accommodating the load on the structure, without calculating or determining the performance level of the structure. The structure performance itself is used to determine the performance level of a structure against an earthquake design based on the level of damage to the structure when it is affected by an earthquake with a certain return period. This research was conducted to determine the level of structural performance based on variations in column with a case study of the Rancacili Silinder II building. Structural performance analysis was carried out using three structural models, the structure with a circular column and a square column (Structure type I) according to existing conditions, the structure with a circular column (Structure type II), and the structure with a square column (Structure type III). The structure type I uses the same column dimensions from base floor to the roof, but structure type II and III the column dimensions change smaller from the base floor to the roof. Determination of performance levels based on ATC-40 with seismic load analysis of spectrum response. For force calculations in using ETABS V.16.2.0. The results of this study indicate that the structure type I has the smallest displacement value among the three models, with a displacement value of the X direction at 50, 198 mm. While the structure type II has the smallest displacement value of the Y direction at 46, 995 mm among the three models. The structure performance based on ATC-40 from the three structural models shows that they are at the same level of performance, Immediate occupancy (IO), where after an earthquake there is only a little damage and has the strength and stiffness approximately the same as the pre-earthquake conditions.

EVALUASI KINERJA STRUKTUR BANGUNAN MENGGUNAKAN PUSHOVER ANALYSIS DENGAN METODE ATC-40 DAN FEMA 356

Pushover analysis is a non-linear static analysis to determine the collapse behavior of a building or structure. The analysis is carried out by giving a static lateral load pattern to the structure, which is then gradually increased by a multiplier until a buliding movement target is reached. This final assignment research was conducted to determine the performance point based on ATC-40, to determine the performance level based on ATC-40, and to determine the performance level based on FEMA 356. The research method used the response spectrum with the SAP2000 v14 program. The result of the performance point in building with the values of Sa = 0,737, and Sd = 0,200 for the push X, while the values of push Y Sa = 0,680, and Sd = 0,225. The calculation of ATC-40 in building shows the value of the drift ratio in the X direction 0,01165 and the drift ratio Y direction 0,0127 at the level of performance Immediate Occupancy (IO). The result of FEMA 356 calculation in building shows the value of the lateral displacement target structure of the X direction structure = 0,00437 (0,437 %), and the value of the lateral displacement target of the Y direction structure = 0,006 (0,6 %) and at the level of performance Immediate Occupancy (IO). Then it could be concluded that The Dental &amp; Mouth Hospital of UGM Prof. Soedomo, was at the level of performance Immediate Occupancy (IO), meaning that the building was still safe and could be reused after the earthquake and don’t occured serious demage.

Assessment of a 12-story Reinforced Concrete Special Moment Frame Building Using Performance-Based Seismic Engineering Standards and Guidelines: ASCE 41, TBI, and LATBSDC.

A 160-foot (≈ 49 m) tall 12-story reinforced concrete special moment frame building is designed following ASCE 7-16 and ACI 318-14, and assessed using three Performance-Based Seismic Engineering (PBSE) standards and guidelines including ASCE/SEI 41, the Tall Buildings Initiative (TBI) guidelines for performance-based design of tall buildings, and the Los Angeles Tall Buildings Structural Design Council (LATBSDC) procedures. The assessments are performed at the combination of two performance and hazard levels including Collapse Prevention (CP) at the risk-targeted maximum considered earthquake (MCER) hazard level and Immediate Occupancy (IO) at a frequent ground motion level with 50 percent probability of exceedance in 30 years, i.e. serviceability performance level. Based on the recommendations of each of the three PBSE documents, nonlinear finite element models are implemented in OpenSees. Through nonlinear time-history response analyses, the finite element models are subjected to eleven ground motions that are selected following the ground motion selection recommendations in ASCE 7-16. Assessment results indicate that for the serviceability performance level, the code-compliant building meets the design requirements of the three PBSE documents for the interstory drift ratio and inelastic deformation of the structural components. At the MCER hazard level, although the building essentially satisfies the design requirements for the peak interstory drift ratios and inelastic deformation, the mean of the residual interstory drift ratios as well as the envelope of the residual drift ratios do not meet the limits of the TBI and LATBSDC guidelines. The results indicate that the newly designed building meets the ASCE 41 acceptance criteria but does not meet the design requirements set in TBI and LATBSDC guidelines.

The Structural Performance Analysis of Base-Isolated Hospital Buildings with Analysis Modal (Case Study: General Hospital in Labuhan Batu Utara Regency Area)

The development of earthquake analysis towards structures is required to prevent damages and loss in buildings due to earthquakes. The base isolation system is a simple design approach for earthquake-resistant buildings to protect the structures and components from the risk of earthquake damages by using the concept of reducing earthquake forces. This research aims to analyze the performance of a general hospital building in Labura Regency area in order to know the safety of the building in terms of period, frequency, base shear force, displacement and earthquake force, used the base isolators and without the base isolators. The method used is response-spectrum dynamic analysis by ETABS v2016 program. From the calculation of structural analysis, the application of base isolation is able to build up the period of the structure, therefore, the maximum acceleration of earthquakes can be reduced at certain period. There is an average increase by 48.21% of the structural period compared to non-isolated base structure, and the frequency that occurs in structures using base isolators is smaller than without base isolators. The friction force obtained is smaller compared to the structures without dampers. Base-isolated building structures observed have bigger displacement than non-base isolated structures. The average rise of the building displacement is 27.14% at x and 2.74% at y directions. In base-isolated structures, earthquake forces are reduced averagely by 57.51% at x and 82.73% at y directions. The analysis of structural performance, General Hospital in Labura Regency is categorized to Immediate Occupancy (IO) in which the building structures are safe with no significant risk of fatalities due to structural failures, there are no any significant damages and the building can be used and functioned/operated again immediately.

Limit State Exceedance Probabilities of Building Performance under Earthquake Excitation Using Rupture-to-Rafters Simulations

ABSTRACT In this paper, the performance of two 18-story steel moment frame buildings (UBC 1982 and 1997 designs) in southern California under plausible San Andreas fault earthquakes in the next 30 years is quantified. The approach integrates rupture-to-rafters simulations into the PEER performance-based earthquake engineering (PBEE) framework. Using stochastic sources and computational seismic wave propagation, three-component ground motion histories at 636 sites in southern California are generated for 60 scenario earthquakes on the San Andreas fault. The ruptures, with moment magnitudes in the range of 6.0–8.0, are assumed to occur at five locations on the southern section of the fault. Two unilateral rupture propagation directions are considered. The 30-year probabilities of all plausible ruptures in this magnitude range and in that section of the fault, as forecast by the United States Geological Survey, are distributed among these 60 earthquakes based on proximity and moment release. The response of the two 18-story buildings hypothetically located at each of the 636 sites under three-component shaking from all 60 events is computed using 3-D nonlinear time-history analysis. Using these results, the probability of the structural response exceeding Immediate Occupancy (IO), Life-Safety (LS), and Collapse Prevention (CP) performance levels under San Andreas fault earthquakes over the next 30 years is evaluated.

Seismic performance assessment of conventional CLT shear wall structures and post-tensioned CLT shear wall structures

This paper presents the performance-based seismic assessment framework on conventional CLT shear wall structures (C-CLTStrs) and post-tensioned CLT shear wall structures (PT-CLTStrs). Numerical models of both the conventional CLT shear walls and the PT CLT shear walls were developed and calibrated with experimental results. A direct displacement-based design (DDD) procedure was then developed and demonstrated by the design examples of one 8-storey C-CLTStr and a set of 8-, 12-, and 16-storey PT-CLTStrs. Corresponding simplified structural models were developed. A series of pushover and time-history dynamic analysis was conducted afterwards to calibrate the calculated structural performance objectives with the design targets of the DDD procedure. Finally, using 50 mainshock (MS) and 50 mainshock-aftershock (MSAS) earthquake records, probability seismic demanding analysis (PSDA) were conducted to evaluate two engineering demanding parameters of the structures, namely the maximum inter-storey drift (MaxISDR) and the residual inter-storey drift (ResISDR). The MaxISDR limit states of the PT-CLTStrs are recommended at 0.7%, 1.4%, and 2.2% for the immediate occupancy (IO), life safety (LS), and collapse prevention (CP) hazard levels, respectively. The MaxISDR of the PT-CLTStrs is almost twice that of the C-CLTStrs, while the ResISDR is at most 50% of that of the C-CLTStrs. The damage probability of the 8-storey PT-CLTStr indicated by ResISDR is not significantly sensitive to the consideration of aftershocks seismic input, whereas, when aftershocks are considered, up to a 7.0% difference under the LS hazard level is caused in the damage probability of the 8-storey C-CLTStr indicated by ResISDR.

On the quantification of collapse margin of a retrofitted university building in Beirut using a probabilistic approach

The scope of this study is to investigate the feasibility and performance of several retrofitting techniques on an existing building in Beirut Arab University (BAU). The implemented retrofitting techniques were adding RC shear walls (SW) and steel bracing systems. Simulation and analysis procedures were performed in a nonlinear platform. Models are designed based on ACI 318-14 and ANSI/AISC 360-10 for concrete and steel, respectively. Non-linear time history analysis (NL-THA), non-linear static analysis (NL-SA) and collapse margin ratio are carried out to evaluate the performance of existing and retrofitted structures. Incremental dynamic analysis (IDA) curves are then generated and used to develop the seismic fragility curves. Three different strong ground motions are used in the analyses by referring to the UBC 1997 requirement. The IDA curves are compared based on five performance levels; operational phase (OP), immediate occupancy (IO), damage control (DC), life safety (LS), and collapse prevention (CP). The fragility curves and the calculated CMRs indicated that the shear wall and steel bracing systems both provide good seismic improvement and are able to achieve strengthening solution targets for an existing building system; however, the performance of RC-SW system under seismic excitation was much better. To this, RC-SW is considered as the most appropriate technique for retrofitting the main building of Beirut Arab University.

Analytical Assessment of Reinforced Concrete Frames Equipped with TADAS Dampers

In recent years, it is considerably attempted to develop the concept of energy dissipation as an applicable technology to overcome the energy released by earthquakes. The passive control systems such as metallic dampers have been widely considered. Energy dissipating dampers are used to modify the response of structures as well as to reduce the damages in structure members. This study is conducted to investigate the seismic response of three normal concrete moment resisting frames with 4, 7 and 10 stories equipped with Triangular Added Damping and Stiffness (TADAS) metallic dampers. OpenSees software is employed for nonlinear time-history analysis using seven earthquke records to determine the structure response. The results showed the considerable modifed seismic responses. It is observed that the story drifts are constant and the maximum values in retrofitted 4, 7 and 10 story frames have been decreased 54%, 56% and 55%, respectively. Also, the maximum floor acceleration, the maximum roof displacement and the maximum story shears are lower in the frames equipped with damper and the lateral behavior of the majority of the retrofitted frame members has been upgraded to Immediate Occupancy (IO) and Live Saftey (LS) performance level.

On the Performance of a Multi Story Irregular Apartment Building Model Under Seismic Load in Indonesian Moderately High Seismicity Region

Purbalingga is regency with a potential moderately high seismicity requiring compliance of planning and implementation rules of the earthquake-resistant structural system. The purpose of this research is to evaluate the performance of a ten-story irregular apartment building model in Purbalingga due to the seismic load. The study is necessarily conducted to provide information on impacts and mitigation strategies that should be implemented. This research was conducted based on the seismic capacity of 2002 and 2012 Indonesian National Standard (SNI) including linear static analysis, dynamic response analysis, and pushover analysis. Based on the direct static review, it shows that the base shear is reduced and the drift ratio level decreases respectively for X and Y direction.Meanwhile, based on the dynamic response analysis, the drift ratio level also decreases respectively for X and Y direction. Also, the pushover analysis indicates that the performance of this apartment building model is still at Immediate Occupancy (IO) level as the post-earthquake damage state that remains safe to occupy, essentially retains the pre-earthquake design strength and stiffness of the structure. The risk of life-threatening injury as a result of structural damage is very low, and although some minor structural repairs may be appropriate, these would generally not be required before occupancy

Strengthening Using Type-V Bracing for Structural Integrity of Reinforced Concrete Frame Resists Earthquake Loads

Relatively new seismic code has been introduced in Indonesia (SNI 1726-2012) which affects old structures. Mostly, the existing structures does not meet the requirement of new regulation: overstressed. Therefore, it is important to strengthen reinforced concrete (RC) structure in order to meet the performance level and structural behaviour satisfied. In this study, the retrofitting method was performed by using a type V steel braces both external and internal settlement. Clearly, the advantage of braces is significantly increases lateral capacity where small amount of mass also invoked into the structures. Computer simulation using SAP2000 found that most of the structures have been overstress on its components, indeed reinforcement is necessary with braces. Nonlinear pushover analysis was performed on type-V braces with and without perimeter frames which reviewed structural performances. Evaluation of 3, 5, 8 and 10 storey structures designed under previous code and failures of structural components found after the most recent code to be implemented. Lateral load capacity and structural performance were observed to determine the capability dissipate earthquake energy that occurred in structural components with plastic joints distribution. Results of study provides comparison of behaviour and performance of each model. It found that the ultimate capacity of each model produced can increase base shear up to ± 150% larger compared to the existing structures. From pushover analysis, the curve of each model measured for performance level and it found to be set of the Operational (O), Immediate Occupancy (IO) and it has not been exceeded the Live Safety level (LS) as the result of structural strengthening using bracing. The bracing applied will provide a higher lateral capacity and minimum level of damage.