Performance-based Design Philosophy Research Articles

Comparison of Highway Bridge Seismic Design in Europe and China through a Case Study

With accumulated experiences of bridge damage learned from past earthquake events, the highway bridge seismic design approach is evolving from time to time. It is important for both China and Europe to learn from each other to improve seismic design approaches. A thorough comparison relating to the seismic hazard level, response spectra, and ductility considerations between Eurocode 8 and the Chinese specification is made in this study. Both of these two specifications are based on performance-based design philosophy. However, the Chinese specification is based more on deformation capacity than on strength. The design approach specified in the Chinese specification is more consistent with experiences obtained from past earthquake events than the method adopted in Eurocode 8. Case study shows that bridge designed in accordance with Eurocode 8 could satisfy the force requirement under earthquake action E1 as specified in the Chinese specification but could not satisfy the displacement requirements under earthquake action E2. It is expected that the method adopted in the Chinese specification could provide conservative seismic design in both aspects of seismic forces and displacements.

Resilience-Based Design of Infrastructure: Review of Models, Methodologies, and Computational Tools

The quest to answer the longstanding question of how safe is safe enough has led to an evolution of design philosophies. The traditional philosophy has been based on ensuring that system capacity exceeds demand. This philosophy has been manifested in such design methods as allowable stress design (ASD) and load and resistance factor design (LRFD). The level of safety in these methods is commonly calibrated to the acceptable practice using structural reliability methods. Such an approach to design aims to balance life safety and construction costs and works relatively well for service loads under which strength is nearly always a sufficient representative of system capacity. Under extreme loads, however, not only do factors such as ductility or energy-dissipation capacity come into play, but also the consequences of failure are vastly larger and may go beyond the failure site. For this reason, the more modern design philosophy of performance-based design emerged. According to this philosophy, a system is designed to meet a target performance, defined by limits on its performance metrics. These metrics were initially defined on structural responses, such as deformations and accelerations, and later evolved into risk measures based on monetary loss, downtime, and casualties. This philosophy is gradually making its way into modern design codes. Typical performance-based criteria focus primarily on what transpires during extreme loads. The need to incorporate the recovery of the system after such events has prompted the design philosophy to make another leap into resilience-based design (RBD). Resilience is defined herein as the ability to recover, within a predetermined period of time, in the aftermath of extreme events. Resilience transcends risk, i.e., a resilience analysis incorporates not only a risk analysis but also a recovery analysis. This paper provides a review of RBD in continuation of PBD and further introduces various applications of RBD into the design and assessment of civil infrastructure. The review covers the state of the art in resilience quantification approaches and associated computational platforms.

Seismic Design of Bolted Connections in Steel Structures—A Critical Assessment of Practice and Research

The importance of connections in steel structures is paramount, not only because it greatly influences the cost of construction and provides room for innovations, but also due to the connections’ impact on global structural behaviour. Therefore, research into innovative connections for seismic applications and related design criteria has significantly grown in recent years. However, it has been pursued mostly on local—connection or frame—levels, leaving the system analysis and code compliance levels with a meagre investigation. Moreover, less than 1% of published papers concerning steel connections and earthquake engineering are review articles. To overcome this gap, this systematic review of more than 240 references, including scientific contributions and design codes in the field aimed to cover both recent research and current shortcomings in practice and regulations. It has been found that European design rules updated to a fully performance-based design philosophy is imminent and is deemed to bring pre-qualified joints and increased complexity. Design rules have been systematized, and current hindrances have been highlighted. A deeper look into research needs and trends showed that investigations in connections for concentrically X braced frames are still a necessity, while developments in self-centring and replaceable connections as well as in simple solutions for increasing damping are expected to modify how joints are designed, as soon as semi-rigid and partial strength connections are more easily allowed by design codes.

Earthquake-Resilient Design of Seismically Isolated Buildings: A Review of Technology

Earthquake Seismic isolation plays an important role in achieving sustainable earthquake resilience communities. Seismic isolation method is a justified, mature, and reliable performance enhancement strategy for a wide range of structural systems and valuable contents. As a result of the targeted response modification, high-performance expectations and earthquake resilience can be achieved during the service life of the structures that are compliant with the design code requirements. Design and analysis procedures of isolation systems in standards were evolved substantially to expand the use of isolation technology and quantify the benefits of isolation systems to overcome the existing impediments. Strictly speaking, new tools are offered to the engineering community to highlight the possible issues that may appear in isolation units beyond the design basis earthquake level to improve the accuracy of response prediction. This paper aims to overview the characteristics of frequently used isolation systems in the industry with mathematical models, design criteria toward sustainable communities, the current state of practice along with the set forth design requirements of selectively well-known standards with special emphasis to the ELF procedure from the perspective of performance-based design philosophy. Additionally, two large-scale seismic isolation applications in the world are given as benchmark studies for the new construction and upgrading scheme in the content of the study.

Probabilistic Performance-Based Optimum Seismic Design Framework: Illustration and Validation

In the field of earthquake engineering, the advent of the performance-based design philosophy, together with the highly uncertain nature of earthquake ground excitations to structures, has brought probabilistic performance-ba... | Find, read and cite all the research you need on Tech Science Press

Probabilistic verses deterministic method of seismic performance evaluation

Seismic performance evaluation of existing buildings by probabilistic approach and by deterministic approach has been compared and benefits of probabilistic approach are highlighted. An old building constructed in the 80s and situated in Indian seismic zone V has been taken for the study. Different retrofitting strategies have been implemented to improve global seismic performance. Effectiveness of any retrofitting scheme is assessed by both approaches. Static pushover analysis has been implemented for deterministic approach. For stochastic approach, a probabilistic-based methodology based on Pacific Earthquake Engineering methodology has been developed. The methodology accounts well the associated uncertainties in the process of seismic evaluation. Incremental dynamic analysis-based fragility curves have been developed. It is concluded that probabilistic approach provides comparatively a broad insight into evaluation process and it accounts capacity, demand and modeling uncertainties and is able to predict the seismic performance of retrofitted buildings to futuristic earthquakes. The study also recommends the implementation of performance-based design philosophy based on probabilistic approach in Indian seismic code to match with developing countries’ current design philosophy.

Optimization of Vibrocompaction Design for Liquefaction Mitigation of Gravity Caisson Quay Walls

AbstractGravity-type caisson walls are a type of popular but easily damaged waterfront construction structure, especially in seismic regions. Various forms of mitigation have been successfully applied to improve their performance when subjected to liquefaction. Establishment of an effective, reliable, and easily implemented liquefaction remedial design procedure based on commonly used ground improvement technology is important. In this study, following the philosophy of performance-based design, a novel optimization process was developed and applied to a well-known case study. The vibrocompaction method was examined within a framework of a well-calibrated case history to hypothetically improve the seismic performance of a damaged caisson quay wall to an acceptable level. This study includes three major steps: first, the constitutive model used in this study for describing liquefaction was calibrated based on the published data; second, a caisson quay wall case history damaged by liquefaction was simulated...

Seismic stability of braced excavations next to tall buildings

It can take many years to complete the construction of deep, wide and long excavations in urban environments. In seismically active areas, there is a finite probability that a significant earthquake could take place during the construction period. The designer and builder are confronted with the need not only to maintain control of ground and retaining wall movements during the normal construction conditions but also to protect surrounding buildings during a seismic event. It follows that the seismic loads from adjacent structures and their foundations must be considered together with the available load pathways through the propping system. The paper considers the available methods of design and proposes a performance-based design philosophy in which the temporary shoring system and permanent installation are designed for static loading conditions and for the seismic condition only in as much as the performance objectives of adjacent buildings are achieved for various levels of earthquake shaking. An example of the use of performance-based design is presented for the effects of a 130 m tall building of 30 m square plan upon the temporary shoring system for a long and wide excavation. The results obtained are compared with code-based calculations and general conclusions are drawn.

Structural fire performance of earthquake-resistant composite steel–concrete frames

Seismic and fire design of a building structure may be two very demanding tasks, especially if included in a performance based design philosophy. For the time being, the necessary harmonization on the regulations concerning these two design fields is almost missing, thus preventing the effective possibility of an integrated design. Besides, while many countries have already moved towards the use of performance-based codes for seismic design, the application of such methodologies for the fire design of structures is still limited in scope. Within this framework, the development of suitable procedures introducing structural fire performance issues for a comprehensive design methodology is needed. In this paper, a numerical investigation for the assessment of the structural fire performance of earthquake resistant composite steel–concrete frames is presented. With reference to a case study defined in the framework of a European Research Project, a great effort was devoted to the identification of the key structural parameters allowing for a possible correlation between the predictable performances under seismic and fire loadings, when these two are considered as independent actions. At the conceptual design level, the most suitable structural solution with respect to both design actions was chosen, including composite beams and circular steel concrete-filled columns. The frame was designed in order to resist severe seismic action according to the ductile design approach provided by Eurocode 8; the parameters affecting members’ sizing were outlined in this phase. Afterwards, the seismic performance of the designed frame was investigated by means of non-linear static analyses; once the seismic performance objectives were met, in order to evaluate the structural fire performance of the whole frame a set of criteria was defined. To this purpose, thermo-mechanical analyses under different boundary conditions were developed and in order to identify the possible mechanisms leading to structural failure, the state of stress at the critical cross-sections at different times of fire exposure was investigated. Another point of main concern was represented by the assessment of the influence of different restraining conditions on the achieved fire resistance rating and kind of structural failure. Moreover, the proposed methodology allowed making an estimate of the amount of axial restraint provided to the heated beams by the surrounding structure; in this view, the importance of choosing column elements in function of their flexural stiffness was revealed, in order to correlate it with the predictable performances under both seismic and fire loadings.

Performance based design of blast resistant offshore topsides, Part I: Philosophy

The philosophy of performance based design of blast resistant offshore systems is an approach by which structural components are allowed to behave in a controlled non-linear characteristic that satisfies the demand criteria for preventing loss of lives, asset protection and integrity of escape routes. As the approach is based on behaviour rather than a prescriptive performance, uncertainties are removed which attributes to a precise design compared with a traditional design method. In the context of offshore installations, particularly for topside structures where safety cannot be compromised, this will lead to an economical design as well as meeting the functionality of a system from pre to post explosion regimes. This paper presents a performance based design philosophy for a typical topside structure which has the merit of being informative to the client and to regulators. This method also assists engineers in the comparison of engineering solutions which can be correlated to performance levels for which the installation has been designed and protected. The paper is divided into two sections. The first section discusses the methodology of the approach accompanied by a design algorithm assessment in which the principles of performance based design are emphasized in order to achieve the specific demand level for attainment of performance objectives. The second section demonstrates its application followed by a design example of a typical offshore topside to assess deck plate resistance against a defined blast load level.