Due to its historical value, the structural evaluations of the Timche that may consist of both non-destructive and destructive tests confronted with difficulties. Thus, up to the feasibilities, the assessments led to non-destructive tests. The geometrical faces, length of the spans, dimensions of the arches, the dome height, and other requirements according to architectural principles were performed. The visual inspections determined that the properties of the material used within the masonry consisted of clay brick and lime mortar. Since getting direct samples from the masonry were ineligible, a request for acquiring unit and joint samples from Cultural Heritage, Handicrafts, and Tourism Organization of East Azerbaijan, were enclosed. The bureau yielded limited handy numbers of masonry units extracted from the Timche and the combination of the used lime mortar inside the building, which is not presentable due to passive defense factors. To grasp the characteristics of the materials, masonry prisms according to the instructions of the American Society for Testing and Materials (ASTM) were constructed in the laboratory.
4.1 Material Properties
Determining the tensile behavior of masonry prisms according to the principles of both ASTM E518/E518M-10 (2010) and ASTM E519/E519M-10 (2010) standards are viable. However, since ASTM E519/E519M-10 (2010) was not applicable for lime mortars, the tensile and bending characteristics of the studied materials regarding the principles of ASTM E518/E518M-10 (2010) have determined. The compressive behavior of the studied materials was performed according to ASTM C1314-07 (2007). In Table 1 and Table 2, details of the experimental outcomes of the studied samples for flexural bond strength and compressive strength have presented, respectively. In Figure 4, laboratory tests for determining compression strength and flexural bond strength of two specimens have been brought.
Table 1: Laboratory performed tests to determine the flexural bond strength of the studied samples according to ASTM E518/E518M-10 (2010)
Specimen No.
|
Test Method
|
Age at Test (Days)
|
Avg. Width (mm)
|
Avg. Depth (mm)
|
Avg. Length (mm)
|
Weight (kN)
|
Max Load (kN)
|
Strength (MPa)
|
1
|
A *
|
28
|
201
|
101
|
460
|
0.152
|
0.260
|
0.084
|
2
|
A *
|
28
|
200
|
100
|
460
|
0.150
|
0.203
|
0.073
|
3
|
A *
|
28
|
202
|
101
|
461
|
0.155
|
0.257
|
0.083
|
4
|
A *
|
28
|
201
|
102
|
460
|
0.153
|
0.277
|
0.086
|
5
|
A *
|
28
|
201
|
99
|
460
|
0.151
|
0.188
|
0.070
|
Average
|
-
|
-
|
201
|
101
|
460
|
0.152
|
0.237
|
0.079
|
Deviation
|
-
|
-
|
0.71
|
1.14
|
0.45
|
0.002
|
0.039
|
0.007
|
CV **
|
-
|
-
|
0.004
|
0.011
|
0.001
|
0.013
|
0.165
|
0.092
|
* It is a third-point loading method that was discussed in ASTM E518 with further details.
** Coefficient of Variation.
Table 2: Laboratory performed tests to determine the compressive strength of the studied samples according to ASTM C1314-07 (2007)
Specimen No.
|
Age at Test (Days)
|
Avg. Width (mm)
|
Avg. Height (mm)
|
Avg. Length (mm)
|
hp/tp Correction Factor *
|
Max Load (kN)
|
Strength (MPa)
|
1
|
28
|
101
|
315
|
200
|
1.077
|
47.4
|
2.53
|
2
|
28
|
102
|
316
|
201
|
1.076
|
51.8
|
2.72
|
3
|
28
|
102
|
318
|
200
|
1.077
|
48.1
|
2.54
|
4
|
28
|
101
|
318
|
199
|
1.079
|
51.0
|
2.74
|
5
|
28
|
100
|
318
|
200
|
1.084
|
50.1
|
2.72
|
Average
|
-
|
101
|
317
|
200
|
1.079
|
50
|
2.65
|
Deviation
|
-
|
0.84
|
1.41
|
0.71
|
0.003
|
1.88
|
0.10
|
CV **
|
-
|
0.008
|
0.004
|
0.004
|
0.003
|
0.038
|
0.040
|
* It is the ratio of the prism height to the least lateral dimension of it according to ASTM C1314.
** Coefficient of Variation.
Considering the erosion, weathering, corrosion, etc., and the historical content of the perusing structure, the accuracy of the excerpted outcomes from the experimentally evaluated specimens may be affected by these factors. However, since the precision of any other non-destructive tests including but not limited to Schmidt hammer test, ultraviolet test, ultrasonic test, or the imposed damage from destructive tests like coring could not be acceptable the prepared and tested samples according to the principles of ASTM E518/E518M-10 (2010) were still in the advantageous position. and was selected as the criteria for evaluating the results. Experimental results and research outcomes for the compressive strength of the masonry material are in good agreement. The same condition was also observed in the ultimate strain obtained from indirect tensile tests and extracted values from the studies. By taking into account, the mentioned obtained values from the lab utilized for numerical modeling of the material behavior.
4.2 Record Selection Criteria
According to the principles of BHRC (2015), the strong ground motions were chosen by considering their magnitude, fault type, epicentral distance, hypocentral distance, soil type, and effective duration. Since a considerable amount of the historical strong ground motions, which took place in Tabriz, were estimated to range between 5 to 8 Richter in magnitude, all of the selected records had a magnitude larger than 6 Richter. The ilk of the most active fault in the construction geography of the Timche is strike-slip, which is located in the northern part of the city on the seismic belt of Alp-Himalaya. Most of the recorded earthquakes in the studied zone have a hypocentral depth of 10 to 20 kilometers, and the perpendicular distance of the site from the fault is about 15 kilometers. The shear wave velocity of the soil in the site ranged between 175m/s to 375m/s. Thus, the records with a hypocentral distance of 0 to 50 kilometers and epicentral distance of 0 to 30 kilometers with aforementioned analogous shear velocities are the focal point of the search for similar records. Concerning the principles of BHRC (2015), the selected records considered in the search procedure should have at least 10 seconds of effective duration. Since it is located in the vicinity of both major and minor faults, almost every constructed building within the city was prone to both near-field and far-field earthquakes. This study also considered near-field records for evaluating the effects. The epicentral distance and high unorthodox values in the velocity time history were considered the signs of only-pulsed records in various research studies (Baker, 2008; Panella et al., 2017; Kohrangi et al., 2019). In this study, the most prevailing selection method has been used, in which the epicentral distances lesser than 10 kilometers were considered only-pulsed records. Eventually, 20 records of strong ground motions, half of which are only-pulsed, were selected for the current study. Since all of the befallen severe earthquakes in Tabriz were belong to the era that there are no measuring devices and there is no information about the site records, all of the relevant data collected from the Pacific Earthquake Engineering (PEER) database. It is essential to mention 16 of the selected records are conjugated, which means the record data is extracted from two different stations to resemble the near-field and the far-field effects of the selected records. The characteristics of selected records for both near-field and far-field ground motions have shown in Table 3.
Table 3 Ground motion records Name, Year, Station, Abbreviation and PGA
|
Record Name
|
Year
|
Station
|
Abb
|
PGA
|
Far field Strong Ground Motions
|
"Coyote Lake"
|
1979
|
"San Juan Bautista_ 24 Polk St"
|
CSN
|
0.118
|
"Darfield_ New Zealand"
|
2010
|
"Christchurch Cashmere High School"
|
DCN
|
0.297
|
"El Mayor-Cucapah_ Mexico"
|
2010
|
"El Centro - Meloland Geot. Array"
|
EEN
|
0.439
|
"Imperial Valley-06"
|
1979
|
"Calexico Fire Station"
|
ICN
|
0.277
|
"Kobe_ Japan"
|
1995
|
"Kakogawa"
|
KKN
|
0.324
|
"Landers"
|
1992
|
"Coolwater"
|
LCN
|
0.417
|
"Superstition Hills-02"
|
1987
|
"Brawley Airport"
|
SBN
|
0.284
|
"Westmorland"
|
1981
|
"Niland Fire Station"
|
WNN
|
0.176
|
"Parkfield"
|
1966
|
"Cholame - Shandon Array #8"
|
PCN
|
0.272
|
"Duzce_ Turkey"
|
1999
|
"Lamont 1062"
|
DLN
|
0.259
|
Near field Strong Ground Motions
|
"Coyote Lake"
|
1979
|
"Gilroy Array #4"
|
CGO
|
0.422
|
"Darfield_ New Zealand"
|
2010
|
"Christchurch Botanical Gardens"
|
DCO
|
0.190
|
"El Mayor-Cucapah_ Mexico"
|
2010
|
"Westside Elementary School"
|
EWO
|
0.281
|
"Imperial Valley-06"
|
1979
|
"Agrarias"
|
IAO
|
0.472
|
"Kobe_ Japan"
|
1995
|
"Port Island (0 m)"
|
KPO
|
0.567
|
"Landers"
|
1992
|
"Yermo Fire Station"
|
LYO
|
0.245
|
"Superstition Hills-02"
|
1987
|
"Kornbloom Road (temp)"
|
SKO
|
0.432
|
"Westmorland"
|
1981
|
"Parachute Test Site"
|
WPO
|
0.232
|
"Parkfield-02_ CA"
|
2004
|
"Parkfield - Fault Zone 9"
|
PPO
|
0.153
|
"Kocaeli_ Turkey"
|
1999
|
"Yarimca"
|
KYO
|
0.322
|
Each record was composed of vertical and two perpendicular pivots. Standards and design codes, including but not limited to (Eurocode 8, 2005; ASCE/SEI 7-10, 2013; Standard 2800-15, 2015) normalize earthquake records for nonlinear dynamic analysis by scaling PGA of the ground motion to 1.0 g and applying the modification factor to them that obtained from comparing the convoluted response spectrum of the selected records to the standard design spectrum in the determined range of Time period for the studied structures. In this study, the records according to the principles of BHRC (2015) have been scaled and implemented in numerical modeling using ABAQUS FEM software. After record normalization, the stress and strain outputs of the Karbandi subjected to the near and far-field records have been extracted and brought for further consideration, as explained in the Time History Analysis section.
4.3 The Failure Criterion
According to principles of structural mechanics, the failure mechanism in skeleton structures, took place when the formation of plastic hinges makes the whole structure or some parts of it unstable. Since masonry structures are continuous nonhomogeneous elements with low integrity, the determination of failure mechanism for them is more complicated than one-dimensional elements. According to the experimental and numerical outcomes of many pieces of researches (Andreaus, 1996; Noor-E-Khuda et al., 2016; Bui et al., 2019), the ultimate failure of the masonry elements took place in a plane or planes of crack formation in which some part of the masonry become unstable. Hence, the failure of the Timche, which leads to the mechanism of some or all sections of it, was occurred during the formation of the first plane of failure. The failure point is the ultimate plastic strain of the masonry elements extracted from experimental results of masonry prisms in compression and flexure, which were used for compressive and tensile behavior of masonry elements, respectively. The corresponding failure drift in Nonlinear static analysis was considered to be the failure drift of the structure, in which it was comprehensively collapsed, and the analogous Damage Content (DC) of it was deemed equal to one. The zero point of the Damage Content (DC), when the plastic behavior of the structure corresponds to the yield point of the bilinear pushover curve of the Timche, is initiated. Correspondingly the failure content of the Timche for the near-field and the far-field earthquakes is evaluated.