Pull-in capacity of unfilled T-connections using Bambusa blumeana bamboo

Abstract

Bolted bamboo connections are ubiquitous in contemporary bamboo structures, yet their performance remains under-researched—particularly in configurations without cement mortar infill. This study investigates the structural behaviour of a T-shaped fish-mount joint, commonly used to connect two angled bamboo members. The joint consists of two culms connected using through-culm threaded rods—one straight and one with a hooked end. A critical loading scenario arises when the threaded rod is pulled through the bamboo, causing the washer to bear against the outer culm wall. To simulate this, the study replicates the failure mechanism by pushing the rod inward, effectively assessing the rod pull-in capacity. In this context, the study tests one hundred connection specimens made of Bambusa blumeana bamboo poles and threaded rods of 8 mm and 12 mm in diameter, with corresponding nuts and washers. From the experimental results, it then develops three predictive models for estimating maximum capacity: (1) a dimensional analysis model, (2) a regression-based model, and (3) a bending-perpendicular-to-fibre model. Among these, the dimensional analysis model based on bamboo density, culm diameter, and wall thickness demonstrates the best performance, offering a simple, unit-consistent formulation with a strong fit ( $R^{2} = 0.82$ ). Accordingly, the dimensional analysis model is further developed into a practical design formula aligned with the structural bamboo design code ISO 22156:2021, enabling engineers to apply it directly in the design of bolted bamboo connections.

Keywords

bamboo bamboo connection T-connection fish-mouth connection bolted connection

Introduction

Bamboo’s abundance and fast-growing characteristics have made it an integral material for sustainable and affordable housing for over a billion people across the globe (Bundi et al., 2024; Md Tahir et al., 2023). Traditional bamboo houses use artisanal joineries such as lashed connections, carpentry joints, etc. (Alarcon, 1991; et al., 2025). Such joineries are often temporary (Widyowijatnoko and Trautz, 2012; Zhang, 2017), dependent on craftsmen’s tools and skills, and have unknown structural performance (Disén and Clouston, 2013). Furthermore, the connection assembly is complex due to the combination of natural variability of bamboo poles, their peculiar geometry, and anisotropic properties (Hong et al., 2019). In this regard, numerous engineered (Aniñon and Garciano, 2024; Benitez et al., 2019) and innovative (van Wassenhove et al., 2021; Barnet and Jabrane, 2019) connections have been proposed to address those challenges.

Steel dowels are widely used to connect bamboo members (Deng et al., 2025; Paraskeva et al., 2019) because they provide a practical solution to address the material’s irregular geometry and hollow cross-section. To prevent common failure modes in dowelled joints, such as local crushing and splitting of the culm wall, reinforcement methods including mortar infill (Correal et al., 2021) and radial confinement (Hu et al., 2021; Moran and García, 2019) are applied. Recent research also explores hybridization of culm and slat elements to reduce variability and establish predictable load paths (Villegas et al., 2019), while engineered bamboo products (Wahan et al., 2022; Zhao et al., 2025) are developed to overcome the geometric limitations of natural poles. In this context, dowel-type connections represent an efficient approach to the structural joining of bamboo culms, employing nails, screws, and bolts. These connectors are widely available and cost-effective, and they accommodate the intrinsic variability of bamboo poles (Pradhan and Dimitrakopoulos, 2021). Their response (Malkowska et al., 2022; Malkowska et al., 2023; Mouka and Dimitrakopoulos, 2022) and damage mechanisms (Ramful, 2018; Zhou et al., 2022) are predictable, and they can be designed to deliver high stiffness and ductility (Kang et al., 2024; Khodabakhshi et al., 2025).

This study investigates one of the most common connections used in bamboo structures, the T-connection. It is used to join two angled bamboo elements through the traditional fish-mouth, lashing, or fasteners, forming a T-shaped connection (Michiels et al., 2017; Romero Méndez et al., 2017) (see Figure 1(a)). Despite its ubiquitous use, studies on these connections remain limited (Boucher et al., 2025). Axial load tests on limited samples of mortar infilled T-connections exhibited bamboo splitting as the dominant failure mechanism (Dickson et al., 2013). These connections exhibit low moment resistance governed by capacity of the dowel (Cabanas, 2018) and small lever arm between compression and tension zones (Harries et al., 2022). Existing design standards (ISO 22156:2021; Asociación Colombiana de Ingeniería Sísmica, 2012) provide limited guidance and are solely for designing T-connections with mortar infill. To the authors’ knowledge, there are no studies on unfilled T-connections to-date. Understanding the performance of unfilled T-connections could enable its use in lightly loaded connections without the need for reinforcements (e.g. through mortar infill, confinement, etc.).

Figure 1.

Common (a) T-connection used in BASE socialized houses, (b) force transfers, and (c) testing setup.

In this regard, the motivation of this study arises from the need for the engineered design of T-connections for bamboo structures. Note that the T-connection consists of two components: (a) a through-culm threaded rod with a nut-washer bearing at the chord member, which hooks onto (b) the dowel connection in the web element. This study focuses on the first component of the T-connection, without mortar infill. The other component (i.e., the dowel connection in the web member, Figure 1(b)) is known to exhibit a predictable response (Correal et al., 2021; Mouka and Dimitrakopoulos, 2022), and is a theme of a future study. Specifically, this study tests 100 T-connection samples to establish their maximum capacity and damage patterns. It then examines three different prediction models based on mechanics, regression, and dimensional analysis to estimate its maximum capacity. Finally, the results recommend a lower-bound model for designing the T-connection component.

Methodology

All Bambusa blumeana bamboo poles, aged 3–5 years, are sourced from Batangas, Philippines, for this study. The bamboo pole specifications follow ref. (Cacanando et al., 2025), with physical properties presented in Table 1, and possess an average moisture content of 9.1% at the time of testing. The test uses two types of threaded rods of grade E235 (ISO 630:1995), i.e., (a) 8 mm and (b) 12 mm, with nuts dimensions of 8.90 mm and 12.21 mm and washers of 19.87 mm and 27.73 mm, respectively. Each variation has a sample size of 50 specimens.

Table 1.

Physical properties of Bambusa Blumeana bamboo poles.

Physical property	Average	Standard deviation	COV	Minimum	Maximum	5^th percentile	95^th percentile
External diameter, D (mm)	101.917	6.866	0.067	87.588	118.283	90.997	114.809
Wall-thickness, t (mm)	8.768	1.653	0.189	5.969	13.645	6.870	11.882
D/t	11.883	1.994	0.168	3.364	15.669	8.392	14.640
Internode length (mm)	43.74	5.800	0.133	17.7	53.8	34.55	50.335
Density, $ρ$ ( $k g / m^{3}$ )	777.524	125.606	0.162	415.692	1019.48	563.232	952.110

The tests are conducted in the Base Innovation Centre using the Shimadzu AG-X plus 100 kN Universal Testing Machine. The proposed test setup (see Figure 1(c)) applies a vertical compression load on the threaded rod. The other end of the rod is free within the chord member. This represents internal forces in the T-connections, for instance, in bamboo trusses under load (see Figure 1(b)). Herein, the diagonal web member is under tension and pulls on the T-connection, whereas the vertical web member is under compression and provides restraint. This causes compression on the cross-section of the chord member. The loading rate is set to 5 mm per minute, which ensures all specimens fail within 3-7 minutes of loading (following the ISO 22157:2019 guidelines).

Results and discussion

Figure 2 presents the force-displacement response of the T-connection samples. The maximum observed force, i.e. $F_{\max}$ is similar for both diameters of threaded rods, regardless of the failure type. For 8 mm threaded rods, $F_{\max}$ = 3.78 ± 1.56 kN (CV = 0.41), whereas for 12 mm threaded rods $F_{\max} =$ 3.73 ± 1.65 kN (CV = 0.44).

Figure 2.

Force-displacement response of the connections with (a) 8 mm and (b) 12 mm threaded rods.

As the specimen is loaded, the compression force induces localized ovalization of the cross-section, causing the softening of the force-displacement curve. The damage modes at failure differ between the specimens. The 12 mm threaded rod specimens exhibit splitting on the top and sides of the chord (see Figure 3(a)). This is similar to the failure observed from the ISO 22157:2019 bending perpendicular to fibres test (see Figure 4). On the other hand, the 8 mm threaded rod specimens fail by splitting originating at the rod’s perimeter (see Figure 3(b)). The failure is likely a combination of the bending perpendicular and localised shear failure of the top wall. The difference in the failure modes between the 8 mm and 12 mm rods is likely due to the smaller stress area in the 8 mm threaded rod, which caused a localised failure. Lastly, note that all observed failure modes are governed by the brittle damage modes of bamboo. Such damage modes are influenced by the natural variability in geometry and mechanical properties of bamboo and brings a significant scatter in the test data in Figure 2.

Figure 3.

Typical failure in tests with (a) 12 mm and (b) 8 mm threaded rods.

Figure 4.

Bending perpendicular test based on ISO 22157:2019.

Developing prediction models

This section evaluates methods for estimating the maximum capacity $F_{\max}$ of the connection. As a first estimate, it explores theoretical and statistical methods, based on prior research in similar fields.

Bending perpendicular model

The 12 mm threaded rod specimens exhibit a failure mode resembling bending perpendicular to fibres, i.e., diametric compression with splitting at one or multiple quadrants (i.e., N, S, E, or W, see Figure 4). This study estimates, as a first approach, the capacity of this failure mode using the principles of bending strength perpendicular to the fibres $f_{m 90}$ as per ISO 22157:2019. Specifically, the capacity $F_{\max}$ of the connection in this failure mode can be calculated from equations (1)–(4), contained in ISO 22157:2019:

f_{m, 90, N S} = \frac{M_{N S} ({R - R}_{i} - h)}{L t h R_{i}}

(1)

f_{m, 90, E W} = \frac{M_{E W} (- {R + R}_{o} + h)}{L t h R_{o}} - \frac{F_{E W}}{2 L t}

(2)

M_{N S} = (F_{N S} \frac{R}{π}) (1 - (\frac{t^{2}}{12 R^{2}}))

(3)

M_{E W} = (F_{E W} \frac{R}{π}) (1 - (\frac{t^{2}}{12 R^{2}})) - \frac{F_{E W} R}{2}

(4)

Note that in equations (3) and (4), the expression $\frac{t^{2}}{12 R^{2}} \approx 0$ for B. blumeana species (Cacanando et al., 2025). Combining equations (1) to (4) and taking $\frac{t^{2}}{12 R^{2}} \approx 0$ simplifies the expressions for $F_{N S}$ and $F_{E W}$ (Mouka et al., 2022):

F_{N S} = \frac{f_{m, 90, N S} L t h R_{i}}{(\frac{R}{π}) ({R - R}_{i} - h)}

(5)

F_{E W} = \frac{f_{m, 90, E W} L t h R_{o}}{R (\frac{1}{π} - \frac{1}{2}) ({- R + R}_{o} + h) - 0.5 R_{o}}

(6)

The subscripts N, S, E, and W refer to the quadrants where the failure is observed (see Figure 4). The symbols, i.e. $h = R - \frac{t}{\ln (\frac{2 R + t}{2 R - t})}$ is the approximate neutral axis, $R = 0.5 (D - t)$ is the radius of the centroid, $R_{i} = 0.5 (D - 2 t)$ is the inner radius, and $R_{o} = 0.5 D$ is the outer radius of the cross-section of the chord.

The equations depend on the strength $f_{m, 90}$ , effective length L, external diameter D, and wall thickness t of the chord member. The parameters t and D are measured from the 100 specimens, while $f_{m, 90, NS} = 11.52 N / {mm}^{2}$ and $f_{m, 90, E W} = - {5.14 N / mm}^{2}$ are obtained from ref. (Cacanando et al., 2025). The effective length $L$ relates to the chord length (see Figure 1(c)). Note that in the ISO 22157 bending perpendicular tests, $L = D$ , and a line load creates uniform stress along the length of the specimen. In contrast, this study applies a concentrated transverse load to the chord member much longer than its diameter, with the stress reducing to zero at a finite distance from the load. Though finite element analysis could make a refined estimate, this study assumes, as a first approach, the length of the stressed region, or the effective length, $L = a D$ . The coefficient a is determined experimentally.

Figure 5(a) shows scatter plots of the experimental $F_{\max}$ fitted with equation (5), which predicts the maximum failure force at the N and/or S quadrants, where using $L = 3.6 D$ gives the best fit (see Table 2, R² = 0.57 - 0.65). This suggests that the stress from the applied point load extends up to approximately 1.8D on either side of the rod. The distance (3.6D) is smaller than the total chord length, indicating the specimen ends are not stressed. Fitting the experimental results to the E-W prediction model using equation (6), returns a length of $= 6 D$ , with $R^{2} = 0.34 - 0.44$ (see Table 2). Even though this failure mode was observed for the 12-mm rod only, for completeness, Figure 5 also presents the results for the 8 mm diameter threaded rods.

Figure 5.

Predicted values plotted against observed values for: (a) NS and (b) EW failure.

Table 2.

Predicting equations and their corresponding $R^{2}$ for the Edge Bearing Model.

Predicting equation	Equation label	( $F_{p r e d}$ vs $F_{\max}$ ) R ²
Predicting equation	Equation label	8 and 12 mm rods combined	12 mm rod	8 mm rod
$F_{p r e d, N S} = \frac{{3.6 f}_{m, 90, N S} D t h R_{i}}{(\frac{R}{π}) ({R - R}_{i} - h)}$	(7)	0.62	0.65	0.57
$F_{p r e d, E W} = \frac{{6 f}_{m, 90, E W} D t h R_{o}}{R (\frac{1}{π} - \frac{1}{2}) (- {R + R}_{o} + h) - 0.5 R_{o}}$	(8)	0.40	0.44	0.34

Regression analysis

The second model considered in this study is based on regression analysis. This section uses both linear equation (9) and non-linear (power) regression models equation (10) to make a prediction

F_{p r e d}

of the maximum force

F_{\max}

F_{p r e d} = β_{0} + β_{1} X_{1} + β_{2} X_{2} + \dots + β_{n} X_{n} + ε

(9)

\ln (F_{p r e d}) = β_{0} + β_{1} \ln (X_{1}) + β_{2} \ln (X_{2}) + \dots + β_{n} \ln (X_{n}) + ε

(10)

where,

β

terms are coefficients,

X_{1}, X_{2}, \dots X_{n}

are independent variables, and

ϵ

is the error. Based on the measured parameters,

D, t,

and

ρ

are chosen as the independent variables and are used to develop the regression models. The study evaluates all possible combinations of these variables to find the best-fit equations with the highest coefficient of determination

R^{2}

(see Table 3).

Table 3.

Best performing regression models.

Model type	Variable count	Equation ( $F_{p r e d}$ is in N)	Equation label	Variables (units) in the equation	R²
Linear	3	$F_{p r e d} = - 17461 + 801 t + 31 ρ - 0.016 ρ^{2}$	(11)	$t (m m)$	0.84
				$ρ (k g / m^{3})$
				$ρ^{2} {(k g / m^{3})}^{2}$
	2	$F_{p r e d} = - 4619 + 42 t^{2} + 6.3 ρ$	(12)	$t^{2} (m m^{2})$	0.82
	2	$F_{p r e d} = - 4619 + 42 t^{2} + 6.3 ρ$	(12)	$ρ (k g / m^{3})$	0.82
	1	$F_{p r e d} = 714 + 37 t^{2}$	(13)	$t^{2} (m m^{2})$	0.58
Non-linear	2	$F_{p r e d} = 0.0054 t^{1.85} ρ^{1.41}$	(14)	$t (m m)$	0.84
	2	$F_{p r e d} = 0.0054 t^{1.85} ρ^{1.41}$	(14)	$ρ (k g / m^{3})$	0.84
	1	$F_{p r e d} = 107 t^{1.6}$	(15)	$t (m m)$	0.53

Herein, considering both the simplicity (fewest parameters) and goodness-of-fit (highest $R^{2}$ ), the best performing model is the equation (14) (see Table 3). Figure 6 plots $F_{p r e d}$ (from equation (14)) against the observed $F_{\max}$ of all test specimens. Note the high reported $R^{2} = 0.84$ , indicating a good prediction regardless of the threaded rod diameter.

Figure 6.

Regression prediction model plotted against the observed data.

Dimensional analysis

Although regression analysis is commonly used for prediction, it lacks physical sense since the units on both sides of the equation do not match. A more accurate approach involves using dimensional analysis (Mouka and Dimitrakopoulos, 2022) to derive models with consistent units. The effectiveness of this method primarily depends on understanding the parameters that impact the dependent variable (herein, maximum force,

F_{\max}

). In this case, the chosen independent variables are: wall-thickness t, external diameter D, rod diameter d, and test density

ρ

(same as that of Section: Regression analysis). Table 4 presents the dimensions of these variables.

Table 4.

Considered variables with their units and dimensions.

Symbol	Unit	Dimensions
$F_{\max}$	$\frac{kg m}{s^{2}}$	$\frac{M L}{T^{2}}$
D	m	L
t	m	L
ρ g ()*	$\frac{kg}{m^{3}} \times \frac{m}{s^{2}}$	$\frac{M}{L^{2} T^{2}}$
d	m	L

(*) gravitational acceleration is used to enable dimensional compatibility with maximum force $F_{\max}$

Using the Buckingham Pi theorem, the considered $Π$ groups are: $Π_{1} = \frac{F_{\max}}{ρ g t^{3}}$ , $Π_{2} = \frac{D}{t}$ , and $Π_{3} = \frac{d}{t}$ . Taking, $Π_{1} = f (Π_{2}, Π_{3})$ , we get

\frac{F_{\max}}{ρ g t^{3}} = f (\frac{D}{t}, \frac{d}{t})

(16)

And solving for

F_{\max}

results in:

F_{\max} = ρ g t^{3} f (\frac{D}{t}, \frac{d}{t})

(17)

The relationship between $Π_{1}$ and $Π_{2}$ or $Π_{3}$ is presented in Figure 7 and Table 5. The fit is noticeably better for the ratio $D / t$ than for $d / t$ , which aligns with earlier observations (see Section: Regression analysis), indicating that the threaded rod diameter $d$ has little influence on the maximum capacity. As a result, further analysis focuses on expressing $Π_{1}$ as a function of $D / t$ using linear and power regression models (i.e. Equations (9) and (10) in Section: Regression analysis) to return the prediction $F_{p r e d}$ of the maximum force $F_{\max}$ . The results are summarised in Table 5, showing that power regression (equation (18)) not only yields a high R² but also provides the simplest model. The proposed prediction model accounts for the influence of geometry and density of bamboo culms on the capacity of the connection. Specifically, when the plot is normalized with respect to ρ·g·t³, the data exhibit low scatter in prediction. As shown in Figure 8, the model provides highly accurate predictions.

Figure 7.

Fit of the Dimensional Model to data.

Table 5.

Dimensional models with their corresponding equations.

Regression type	Predicting equation using the form: $F_{p r e d} = ρ g t^{3} f (\frac{D}{t})$	Equation label	R ²
Power regression	$F_{p r e d} = ρ g t^{3} (3 \times 10^{4} {(\frac{D}{t})}^{1.27})$	(18)	0.82
Linear regression	$F_{p r e d} = ρ g t^{3} (7.8 \times 10^{4} \frac{D}{t} - 2 \times 10^{5})$	(19)	0.81

Figure 8.

Dimensional prediction model plotted against observed data.

Discussion

All bamboo poles possess natural variability in mechanical and geometric properties. Consequently, initial scatter arises as the response of the T-connection is governed by the properties of the bamboo chord. In this context, note that all proposed models (see Table 6) give a good prediction of

F_{\max}

even though the scatter in the force-displacement plots is large. The prediction

F_{p r e d}

from both regression and dimensional models return high

R^{2}

values, indicating they estimate

F_{\max}

more accurately than the bending perpendicular model. The poorer fit of the bending perpendicular model likely results from (a) the high coefficient of variation

C V = 0.33

in the bending perpendicular strength

f_{m, 90, N S}

(Cacanando et al., 2025), (b) the exclusion of parameters such as density, which is known to affect strength, and (c) simplified formulation of Equations (5) and (6), which does not adequately account for the boundary conditions of the test. Herein, the best model, considering accuracy, unit consistency, and simplicity, is the one derived from dimensional analysis, equation (18) (

R^{2} = 0.82

). Under this approach, by normalizing into dimensionless relationships using physical and geometric properties such as t, D, and density, the scatter in

F_{\max}

is reduced and a clear trend emerges with high

R^{2}

value, as shown in Figure 8. Although a more refined mechanical model could reduce scatter and improve predictive consistency of the bending perpendicular model, results demonstrate that pursuing this direction is not essential for the present study. In this regard, further research is needed to accurately capture the boundary conditions and resolve the forces acting within the joint.

Table 6.

Summary of the best prediction models.

Model type	Prediction models	Equation label (repeated for clarity)	R ²
Model type	Prediction models	Equation label (repeated for clarity)	$d$ = 8 & 12 mm
Theoretical	$F_{p r e d, N S} = \frac{{3.6 f}_{m, 90, N S} D t h R_{i}}{(\frac{R}{π}) ({R - R}_{i} - h)}$	(7)	0.62
Regression	$F_{p r e d} = 0.0054 t^{1.85} ρ^{1.41}$	(14)	0.84
Dimensional	$F_{p r e d} = ρ g t^{3} (3 \times 10^{4} {(\frac{D}{t})}^{1.27})$	(18)	0.82

Developing a characteristic model for design

The proposed models for $F_{p r e d}$ in Table 6 predict the average trend of the maximum force $F_{\max}$ . However, a characteristic (lower-bound) model is needed for structural design. This section derives a lower-bound trend $F_{p r e d, k}$ of the maximum force based on the dimensional analysis (i.e., equation (18) in Table 6) as it is deemed to perform best. The model is derived using the characteristic 5^th percentile value of the density of the sample (i.e. $ρ_{k} = 539.9 k g / m^{3}$ from ref. (Cacanando et al., 2025)). The approach for deriving the lower-bound model is similar to that of timber engineering (for instance, the embedment strength (Whale and Smith, 1986; EN 1995-1-1:2004)).

The derived lower-bound equation (Equation (20) and Figure 9) is intended for direct use with existing design standards (e.g., ISO 22156:2021) to determine the design capacity of the T-connection’s member subjected to the pull-in of the rod. The equation enables to check whether the joint can remain unfilled or requires cement-mortar infill. It is calibrated for Bambusa blumeana bamboo, and threaded rods of 8 to 12 mm in diameter with standard nuts and washers. Indeed, thick and enlarged washers could lower the transverse stress on the bamboo poles and return higher capacities, but this is beyond the scope of the current study. Crucially, because the equation is dimensionally consistent, it shows promise for use with other bamboo species by simply plugging in their characteristic test density and pertinent $D / t$ ratio. This is the theme for our further study.

F_{p r e d, k} = ρ_{k} g t^{3} (3 \times 10^{4} {(\frac{D}{t})}^{1.27})

(20)

Figure 9.

Lower bound model.

Conclusions

The study presents an experimental analysis of a common connection type in bamboo, i.e., T-connection, without mortar infill. With one hundred experimental tests on the rod pull in capacity, the failure in all tests is brittle, due to the cracking of the culm. Although different cracking pattern is observed for the two diameters, the maximum capacity is similar between the two diameter variations. Three different analytical models are developed. Among them, the dimensional model incorporating bamboo test density, culm diameter, and wall thickness is found to be the most suitable, offering a good fit to the data while remaining relatively simple and dimensionally consistent. The model based on bending perpendicular to fibers returns the lowest fit, indicating the model does not adequately capture the stresses acting on the joint during failure. The regression-based model returns the highest fit; however, the derived equation lacks physical sense as it possesses inconsistent dimensions.

Based on the dimensional analysis model, the study derives a lower-bound equation intended for the structural design of such connections. The proposed equation combines the characteristic 5^th percentile test density with the $D / t$ ratio of the Bambusa blumeana poles to return a safe estimate of the maximum pull-in capacity of the T-connection. The derived equation can be used directly in the design of bamboo connections without mortar infill, following the guidance in ISO 22156:2021. For future research, it is recommended to investigate the influence of washer thickness and size, which can affect the load distribution on the culm. In addition, further research should examine the failure mechanisms of other components in the T-connection, which are beyond the scope of this study.

Footnotes

Acknowledgments

We sincerely thank all the students who contributed to sample preparation, experimental testing, and data recording. In particular, we extend our heartfelt appreciation to Dr Roneh Glenn D. Libre Jr of Mapúa University and Dr David Trujillo of Coventry University for their valuable support and suggestions throughout the study. We thank Jose Hazem Fadrigo for providing the photos of the truss in .

ORCID iDs

Emmanuel Atienza

Luis Felipe Lopez

Carlo Joseph D Cacanando

Nischal PN Pradhan

Author contributions

Emmanuel Atienza: Writing - Original Draft; Software; Data curation. Dominika Malkowska: Methodology; Formal Analysis; Investigation; Writing - Original Draft; Visualization; Software; Data curation. Luis Felipe Lopez: Conceptualization; Resources; Project administration; Funding acquisition. Carlo Joseph D. Cacanando: Investigation; Methodology. Nischal P. N. Pradhan: Conceptualization; Validation; Writing – Original Draft, Review & Editing; Supervision.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research is fully funded by the HILTI Foundation.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data Availability Statement

Data will be made available on request.*

Appendix

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