Data supporting the development of loading protocols for seismic qualification of BRBs considering global performance requirements

The data presented in this article constitute a supplementary material and provide support to the study “Loading protocols for qualification testing of BRBs considering global performance requirements” by Aguaguiña et al. [1]. Three types of datasets are given herein mainly in the form of tables. The first two correspond to databases built based on a compilation of past experimental testing on buckling-restrained braces (BRBs), conducted in different parts of the world. Two distinct objectives motivated such data compilation: (1) to determine a practical range for the parameter named as Yield Length Ratio (YLR), from full-scale and large-scale buckling-restrained braced frame (BRBF) specimens, that allowed for evaluation of the maximum deformation demands of BRBs [1]; and (2) to extract information on the properties of BRB specimens of different types, materials, and origin, for calibration of a numerical model that enabled the simulations of quasi-static cyclic tests of BRBs under five different code-prescribed loading histories (US, EU, CN, JP, and CA) and two proposed global loading protocols (GLP-1 and GLP-2) [1]. The last dataset type corresponds to the results of these numerical simulations, which were conducted using the OpenSees platform. The results show the maximum ductility demand (μmax), cumulative inelastic deformation, in terms of cumulative plastic ductility (CPD) and cumulative plastic strain (CPS), and cumulative hysteretic energy (Ēh) of BRBs as a result of the application of each loading sequence, and they are tabulated by BRB specimen.

BRBs as a result of the application of each loading sequence, and they are tabulated by BRB specimen. ©

Data
The data in this brief constitute supplementary material and provides support to a research on testing protocols for seismic performance assessment and qualification of BRBs [1]. The data provided in this article are composed of six tables and one figure, which are briefly described as follows: 1. Compilation of past experimental studies on BRBs and BRBFs: Two datasets of this type are included in this article.   Table 3, and Table 4 are relevant contents in Section 2.3 that help to fully understand the datasets corresponding to analyses results described in the previous point.

Experimental design, materials, and methods
The following subsections provide a complete description of the methods used for acquisition of the data shared in this article.

Database of past experimental tests of full-scale and large-scale BRBFs
As pointed out in Aguaguiña et al. [1], the values for the parameter YLR typically range from 0.50 to 0.70 in actual buckling-restrained braced frames (BRBFs), depending on the type of end-connections used (i.e., bolted, pinned, welded) and bracing configuration employed (diagonal or chevron). Since the range over which YLR is evaluated directly influences the relative deformation of the BRB, according to Equations (1)e(3) in Aguaguiña et al. [1], it is important to define it in a more realistic way. To this end, the study relied on publicly available data from past experimental tests on BRBFs conducted at a full-scale and large-scale. A total of 12 relevant experimental campaigns, published between 2004 and 2018 [2e23], were compiled to investigate the values that the YLR take in very detailed BRBF specimens. Table 1 summarizes the information regarding the 12 experimental studies.

Database of past cyclic tests of individual BRBs
In Aguaguiña et al. [1], a total of 35 BRB specimens were selected from 16 experimental investigations and tests published between 2002 and 2018 [21,24e41]. These tests were conducted in the In Aguaguiña et al. [1], the 35 BRB specimens described above were classified by strength grade of the steel core material, resulting in three groups: low-yield point steel (G1); mild steel (G2); and high-strength steel (G3). So, analyses results were presented in a summarized form. The last two datasets provided in this data article contain an extended version of the results of the simulation of cyclic tests of BRBs under both code-prescribed loading histories and proposed global loading protocols; the results are listed by 'specimen' instead of by 'specimen group'. Therefore, the data given herein complements the related research article [1] since full results can be consulted, and outcomes can be verified.  Typ. ¼ typical BRB, whose restraining system is composed by a steel tube filled with mortar/concrete surrounding the steel core; All-S ¼ all-steel BRB or "dry" BRB, whose restraining mechanism is composed by steel plates or sections, adapted to the shape of the steel core, typically assembled by bolting; SMPs ¼ BRBs, first proposed by Iwata and Murai [36], whose restraining system is composed by a pair of prefabricated mortar-filled steel channels (referred to as steel mortar planks, SMPs) assembled by welding. AISC* ¼ customized AISC loading protocol; EN15129* ¼ customized EN15129 loading protocol.
United States (2), Hungary (1), Turkey (1), China (3), Taiwan (2), Japan (5), and Canada (2). The tests database includes typical BRBs (20), all-steel BRBs (7), and BRBs with steel mortar planks (8). Further, the dissipative core of the BRBs was made either of low-yield-point steel (4), mild steel (19) or highstrength steel (12) material. Table 2 summarizes the information regarding the 16 experimental studies and the properties of the 35 selected specimens, and it constitutes the analysis matrix of the referred study [1]. The information listed in Table 2 includes: source of data; specimen denomination; loading protocol used for tests; BRB core material specification; steel core material properties (F ysc , ε y ); steel core geometry (A sc , L y ); and BRB yield force and yield deformation (P ysc , D by ).
ε y ¼ core strain, ε b,sc , at first yield of test specimen.
ε y ¼ core strain, ε b,sc , at first yield of test specimen.

Numerical simulation of cyclic tests of BRBs under different loading protocols
The Open System for Earthquake Engineering Simulation (OpenSees) platform [42] was employed for both modeling and numerical simulations of cyclic tests of BRBs. The model was built considering the typical setup for uniaxial cyclic tests of BRBs. It consisted of a two-node truss element with a length equal to that of the yielding segment of the BRB specimen, L y . That is, following the assumption that most of elastic and inelastic deformations take place within the yielding segment of the BRB, small elastic deformations in the transition and connection zones were totally neglected. The BRB model is illustrated in Fig. 1. For further details of the modeling and calibration procedure, the reader is referred to Aguaguiña et al. [1].
As described in Aguaguiña et al. [1], five different code-prescribed loading protocols were evaluated in this study: United States (US); Europe (EU); China (CN); Japan (JP); and Canada (CA). To quantify and compare the demands imposed to BRBs by the five different loading histories, it was convenient to specify the deformation amplitudes, D b , in terms of a common quantity. In this work, all the loading protocols were set in terms of the steel core strain, ε b,sc , which only depends on the geometric properties of the BRB specimen (i.e., L y ). Thus, the US, EU, and CN loading sequences, whose deformation amplitudes were indexed as a function of the BRB design deformation, D bd , needed to be converted so that the deformation levels were also presented in terms of ε b,sc , as the JP and CA loading protocols. Here, two important assumptions were made for estimation of the maximum design demand of BRBs: (1) the design inter-story drift ratio equals the drift limitation in the US, EU, and CN codes; and (2) the design deformation demand, D bd , is evaluated considering two values of the parameter YLR: 0.50 and 0.60. Table 3 presents the US, EU, CN, JP, and CA loading histories, in terms of ε b,sc , used for simulations. Additional details on the definition of the loading histories for analyses can be found in Aguaguiña et al. [1].
In Aguaguiña et al. [1], two new loading sequences, named as GLP-1 and GLP-2, were proposed as global loading protocols for qualification testing of BRBs. These loading histories were derived based on (1) the review of the background and definition of loading protocols for cyclic tests of BRB prescribed in different codes, and (2) the results from numerical simulation of cyclic tests of BRBs under five different loading regimes (i.e., US, EU, CN, JP, and CA). GLP-1 constitutes a loading protocol for an upper level of demand (YLR ¼ 0.50) whereas the loading history GLP-2 represents a lower level of demand (YLR ¼ 0.60). Both loading histories were configured so that a series of conditions and criteria were satisfied (refer to Aguaguiña et al. [1]). GLP-1 and GLP-2 loading protocols are defined in Table 4.
Regarding to analyses results, the force and deformation responses resulting from the application of different loading sequences constituted the main output data from numerical simulations. From the force and deformation data corresponding to each BRB specimen and loading protocol, other performance parameters were computed, including the maximum ductility demand, m max , cumulative inelastic deformation, in terms of cumulative plastic ductility, CPD, and cumulative plastic strain, CPS, and cumulative dissipated energy, E h . The formulae for computation of m max , CPD, CPS, and E h are given in Equations (4) through (7) in Aguaguiña et al. [1]. The post-processing of analyses results was done by using the MATLAB software. Taking into account that the test database is composed of 35 BRBs specimens, and that this study considered five code-prescribed loading protocols (i.e., US, EU, CN, JP, and CA) with two analysis cases for US, EU, and CN, a total of 280 static cyclic loading analyses were performed in OpenSees. On the other hand, the number of static cyclic loading analyses under the two proposed global loading protocols (i.e., GLP-1 and GLP-2) accounted for 70. These results are presented in this article as two datasets. Table 5 presents the results of numerical simulation of cyclic tests of BRBs with code-prescribed loading histories, whereas Table 6 presents the results corresponding to the analyses with the proposed global loading protocols. Table 5 presents the results from numerical simulations of cyclic tests of BRBs under the US, EU, CN, JP, and CA loading histories. The maximum steel core ductility as well as the cumulative imposed demands are reported for each of the 35 BRB specimens considered in Aguaguiña et al. [1].  Table 6 presents the results from numerical simulations of cyclic tests of BRBs under the two proposed global loading protocols, GLP-1 and GLP-2. The maximum steel core ductility as well as the cumulative imposed demands are reported for each of the 35 BRB specimens considered in Aguaguiña et al. [1].