Moran Process Version of the Tug-of-War Model: Complex Behavior Revealed by Mathematical Analysis and Simulation Studies

In a series of publications McFarland and co-authors introduced the tug-of-warmodel of evolution of cancer cell populations. The model is explaining the joint effect ofrare advantageous and frequent slightly deleterious mutations, which may be identifiable withdriver and passenger mutations in cancer. In this paper, we put the Tug-of-War model inthe framework of a denumerable-type Moran process and use mathematics and simulationsto understand its behavior. The model is associated with a time-continuous Markov Chain(MC), with a generator that can be split into a sum of the drift and selection process partand of the mutation process part. Operator semigroup theory is then employed to prove thatthe MC does not explode, as well as to characterize a strong-drift limit version of the MCwhich displays instant fixation effect, which was an assumption in the original McFarlandsmodel. Mathematical results are fully confirmed by simulations of the complete and limitversions. They also visualize complex stochastic transients and genealogies of clones arising inthe model.

A novel inter-story drift limit proposal for TBEC2018 and fragility prognosis with TSC2007

The basic purpose of this paper is to investigate and propose a novel inter-story drift limits for the current Turkish Seismic Code to get easy structural assessment by using software. For this aim, numerical analysis was performed by modeling two types of RC frame structures. One of them is 5 stories, the other of them is 7 stories. Two different concrete classes, C20 and C25, were considered and three tension reinforcement ratios were considered for analysis. Tension reinforcement ratios were determined by half of the compressive reinforcement, equal to compressive reinforcement and double the compressive reinforcement ratio. Incremental dynamic analyses (IDA) were performed on these buildings. In this study to execute IDA, eleven seismic acceleration benchmark records were multiplied with various scaling factors from 0.2 to 1.0. Maximum base shear and corresponding roof displacement responses obtained from IDA curves were generated according to these responses. IDA curves were compared with each other by deriving fragility graphs. According to results, proposed limits for the current Turkish seismic code (TBEC-2018) provide, 0.6%, 2.4% and 3.3% respectively for MN, GV and GC, rather safe limits compared to drift limits presented in the foredate seismic code (TSC-2007).

Assessment of seismic responses toward multi-story buildings of steel special moment resisting frame by considering the setback irregularities

Setback irregularities are considered where discontinuity between adjacent stories is excessive. This irregularity caused the probability of high damage at structures subjected to strong earthquake motion. For this purpose, this study was conducted by modeling the steel special moment frame (SMF) structures using a finite element calculation program with nonlinear static analysis compared to Padang city’s response spectrum. The buildings are also modeled with two types of setbacks: single and multiple setbacks. The results of this paper are discussed including the explanation of many parameters that relate to elastic and inelastic seismic responses of steel special moment frame (SMF). Based on the results, the setback irregularities, both single and multiple setbacks, the inelastic seismic responses are adequately sufficient to SNI 1726 2019 regarding drift limit. The other seismic responses are also discussed in terms of fundamental periods, inter-story drifts, story stiffness, and base shear. Referred to Indonesian Seismic Provision, SNI 1726 2019, it is found that single setback building has more adequate than multiple setbacks in terms of seismic responses. Then, the seismic assessments between these setbacks are explained to address the recommendations about future prevention toward damages and failures in steel buildings.

KINERJA STRUKTUR GEDUNG BETON BERTULANG DENGAN BENTANG KANTILEVER 4 M MENGGUNAKAN METODE ANALISIS PUSHOVER

The advance of technology and design in construction field are developing. Therefore, variety of structural design becomes unique. The shape of building with cantilever seems increasingly atrractive because it is rated to have high architecture. Cantilever form with a longer span of more than 1/3 L is increasingly desirable because it provides a unique exterior appearance,as well as a double function other than as a room can also functioned as a canopy.The building is designed to be a 7-storey building with cantilever beam on the 6th – 7th floor for 4 m. This study used the reference of SNI 03-2847-2013 in designing the main structural elements of reinforced concrete, SNI 03-1726-2012 for the designing the earthquake load, SNI 03-1727-2013 and PPIUG1983 for gravity load planning. From the results of analysis, the interstory drift that occurs both the X-direction and the direction of Y is 50.544 mm and 39.956 mm, each of which qualifies the interstory drift limit according to SNI 03-1726-2012. Structural performance levels are being catagories in immediate occupancy level which means there is no structural damage and the building can be used immediately according to its function AbstrakKemajuan teknologi dan desain di bidang konstruksi semakin berkembang. Hal tersebut, membuat beragamnya variasi desain struktur yang semakin hari semakin unik. Bentuk-bentuk gedung dengan kantilever tampaknya semakin diminati karena dinilai mempunyai arsitektur yang tinggi. Bentuk kantilever yang mempunyai bentang lebih panjang, yaitu lebih dari 1/3 L makin diminati karena memberikan tampilan eksterior yang unik, serta dapat berfungsi ganda selain sebagai ruangan juga dapat difungsikan sebagai kanopi. Gedung yang didesain merupakan gedung 7 lantai dengan balok kantilever pada lantai 6 dan 7 sepanjang 4 m. Penelitian ini menggunakan acuan SNI 03-2847-2013 dalam mendesain elemen struktur utama beton bertulang, SNI 03-1726-2012 untuk perencanaan beban gempa, SNI 03-1727-2013 dan PPIUG 1983 untuk perencanaan beban gravitasi. Dari hasil analisis didapatkan besar simpangan yang terjadi baik arah x maupun arah Y adalah sebesar 50,544 mm dan 39,956 mm, dimana masing-masing memenuhi syarat batas simpangan antar lantai sesuai SNI 03-1726-2012. Level kinerja struktur termasuk level immediate occupancy yang berarti tidak terjadi kerusakan structural dan gedung dapat segera dipakai sesuai dengan fungsinya.

Pushover Response of Multi Degree of Freedom Steel Frames

Seismic codes use the behaviour factor to consider the ductility and the structure's non-linearity to improve the system's overall performance. Generally, Steel moment-resisting frames are characterized by a relatively high period showing high deformability and, foreseen that with stringent damageability criteria, the adopted behaviour factor might not optimally be utilized for achieving better performance of the frames. The design is generally governed by stiffness, leaving behind a complex structural system where the capacity design rules are disturbed and therefore necessitates to relax the drift limits for such frames. Given this and with extensive parametric analysis, the current paper aims to examine the behaviour factor of steel Moment Resisting Frames (MRFs). The parametric analysis has been conducted on rigid steel MRFs of 9, 7, and 5 storeys with bay 4 different bay widths of 9.15 m, 7.63 m, 6.54 m, and 5.08 m. Perimeter frame configuration has been designed using 4 different behaviour factors (q = 6.5, 4, 3, and 2) for a total number of 144 cases. Static nonlinear analysis has been conducted, and consequently, the behaviour factors have been examined. It has been observed that compatibility is required while choosing the drift limit for an assumed ductility class of the code. Doi: 10.28991/cej-2020-SP(EMCE)-08 Full Text: PDF

New proposed drift limit states for box-type structural systems considering local and global damage indices

The maximum displacement responses under the seismic motions are usually considered as an indicator for damage evaluation. It is obvious that appropriate selection of drifts corresponding to various damage levels plays an important role in safety and economy of a design project. Despite the extensive use of the box-type structural system in mass construction and housing industry, there is no special design requirement for this structural system. Due to three-dimensional behavior and interaction of intersecting walls and slabs, it is expected that this system presents different seismic performance in comparison to the conventional shear wall buildings. This study evaluates the overall and story failure mechanism as well as global and local damage indices in this structural system. Maximum allowable drift ratios of 0.45%, 0.65%, and 0.8% are suggested for the immediate occupancy, life safety, and collapse prevention levels, respectively. Moreover, a damage index based on the maximum relative inter-story drifts is proposed to assess the failure in the height domain. According to the assessments, the story and global failure occurring due to considerable damages in main load bearing elements reveals high importance of local damage indices in box-type structural system. Based on the results, it is concluded that the proposed maximum values for drifts in different standards and codes are not reliable. Considering the shear-control behavior and depending on the expected performance levels, the proposed local damage indices are considered as accurate control indicators for box-type structural system.

Comparison of the Reinforced-Concrete Seismic Provisions of the Design Codes of the United States, Colombia, and Ecuador for Low-Rise Frames

This paper presents a comparison between the seismic design provisions of the U.S. ASCE 7, the Colombian NSR-10, and the Ecuadorian NEC-2015 for the design of low-rise reinforced-concrete (RC) frames. The code provisions are compared, illustrating the main differences in the requirements for ductility, strength, and analysis for low-rise RC frames. A four-story building is designed according to each design code, and its performance is evaluated according to ASCE 41-13 using pushover and incremental dynamic analysis. In terms of code language, differences are observed in the strong column-weak beam requirement, the allowable drift limit, and the R and C d factors used by the codes. The results show that the NEC-2015 design is controlled by the strong column-weak beam requirement, while drift limit and strength are the controlling factors in the NSR-10 and ASCE 7 designs. The seismic performance evaluation shows adequate behavior of the three buildings, with columns in the NEC-2015 building showing a slightly better behavior.

Repairing SLS anomalies in NZ seismic code to reduce earthquake losses

The 1992 advent of the Serviceability Limit State (SLS) was for the purpose of eliminating structural and non-structural damage to buildings subjected to small or moderate Earthquakes (EQs). This goal complimented the prior 1976 goal of minimising life-loss due to large Ultimate Limit State (ULS) EQs. However, moderate direct damage and large indirect losses occurred to many medium-rise pre-2004’ precast concrete-framed buildings in Christchurch and Wellington CBDs as a result of small or moderate EQ ground motions in 2010 [1-3], 2013 and 2016 [4-6.] A precedence for a proposed SLS level 1 upgrade was set when Christchurch upgraded to a 50 year recurrence SLS following the 2010-2011 earthquakes [7]. Many modern buildings have been engineered with little regard for SLS [8] nor the goal of eliminating disruption from moderate EQs [9, 10]. The proliferation of SLS building damage and large indirect losses [1] have arisen in NZ primarily because of the specification of a too-small SLS demand which corresponds to a ground motion with 25 year return period and because the Structural Performance factor (Sp) is specified in NZ as 0.7 for SLS, which results in a further 30% reduction of the SLS demand. There are also vulnerabilities in ‘pre-2004’ precast floor-to-beam connection detailing [3]. Cost-benefit analyses show that these building losses may be relieved by first correcting the precast vulnerabilities, then using a SLS limit of 50 year (rather than the current 25 year) return period and/or by specifying Sp = 1. The thus proposed ‘maxi-50 year SLS’ with a drift limit of 0.25%, has the same elastic seismic demand as the 100 year international SLS event [10, 11] (with Sp = 0.7) and will minimise non-structural and business disruption losses in small to moderate earthquakes.