Extended Abstract

Background and Significance
In recent decades, the escalation of man-made threats, particularly bombings and terrorist attacks, has underscored the urgent need for designing architectural forms that comply with the principles of passive defense and civil protection. Explosions in urban areas cause not only direct structural damage but also secondary hazards such as debris projection, fire, and the collapse of non-structural components. These consequences highlight the importance of architectural decisions in mitigating vulnerabilities and enhancing urban resilience. Historically, architectural theorists, from Vitruvius to contemporary scholars such as Francis D.K. Ching, have emphasized the role of form as a fundamental determinant in the performance of buildings. In the context of blast resistance, architectural form plays a pivotal role in how shock waves interact with the building’s geometry, distribute stresses, and ultimately influence the extent of damage.

Objectives of the Study
The present research seeks to identify and evaluate the most influential indicators related to architectural form in the context of blast resistance, with the ultimate aim of providing a design framework that reduces vulnerability and supports the objectives of passive defense. Eleven key indicators were defined for this purpose:

Basic building form type.

Combination of architectural forms.

Articulation of corners.

Roof type.

Compatibility between architectural and structural form.

Adaptation of architectural form with the surrounding environment.

Continuity and integration of architectural elements.

Geometry of the external shell.

Surface-to-height ratio.

Irregularities in building plan.

Irregularities in building façade.

Methodology
The research methodology combines expert-based evaluation and numerical simulation, thereby bridging qualitative and quantitative approaches. In the first phase, expert opinions were collected through structured questionnaires distributed among specialists in civil engineering, architecture, and crisis management. The Analytic Hierarchy Process (AHP) was applied to systematically weight and rank the indicators, enabling a structured comparison of the relative importance of architectural features.

However, relying solely on expert judgment can be insufficient, since the actual behavior of buildings under blast loading is highly complex and influenced by numerous factors that may not be fully captured in subjective evaluations. Therefore, in the second phase, finite element modeling (FEM) was conducted using Abaqus software to simulate the performance of various architectural forms under blast loading conditions. The explosive material was modeled as TNT, and incident wave interactions were introduced to represent realistic blast scenarios. Material properties were defined using a Concrete Damaged Plasticity (CDP) model to capture both compressive and tensile cracking behaviors of reinforced concrete.

Findings
The AHP analysis of expert questionnaires revealed certain priorities among the identified indicators. Experts generally emphasized the aerodynamic qualities of forms, perceiving dome and conical roofs as more blast-resistant, while they considered flat roofs and box-like forms to be less efficient due to their lack of aerodynamic features. Similarly, irregularities in plan and façade were unanimously identified as significant weaknesses in reducing blast resistance.

Finite element analysis, however, presented a different perspective. The simulations demonstrated that flat and compact forms actually performed better in terms of reducing maximum reaction forces at structural supports. Specifically, the flat roof building recorded the lowest force of 18,728 N, while pyramidal and gable roofs showed maximum forces of 38,128 N and 38,666 N, respectively. These findings indicate that the projected surface area exposed to the blast wave is more critical than aerodynamic shape alone. Moreover, irregular geometries resulted in concentrated stress zones, validating the expert concern regarding irregularity, yet challenging their assumption about the superiority of aerodynamic roofs.

Discussion
The comparative analysis between expert judgment and numerical modeling highlighted both alignments and divergences. While both approaches agreed on the detrimental impact of irregularities in plan and façade, their views diverged concerning roof performance. Experts, influenced by subjective notions of aerodynamics, ranked dome and conical roofs higher, whereas finite element results placed flat roofs at the top due to their reduced exposed surface area. This discrepancy underscores the importance of validating expert-based evaluations with numerical modeling, as intuitive impressions may not accurately reflect actual blast dynamics.

The study further emphasizes that the interaction between form and environment plays a secondary yet meaningful role. Buildings aligned harmoniously with their surrounding topography and urban context demonstrated better integration in terms of energy distribution. Similarly, ensuring compatibility between architectural and structural forms significantly improved overall blast resistance, as incongruities between design intent and structural system created weak links under loading.

Innovation of the Study
The primary innovation of this research lies in the integration of multi-criteria decision-making (MCDM) with finite element modeling to provide a comprehensive evaluation of architectural form under blast loading. Unlike previous studies that focused solely on expert opinions or isolated numerical simulations, this research combines both approaches to reveal discrepancies and strengthen the reliability of findings. By systematically identifying eleven indicators and subjecting them to both qualitative and quantitative validation, the study offers a holistic framework for architectural decision-making in blast-resistant design.

Applications and Implications
The findings of this research provide practical insights for architects, engineers, and policymakers engaged in the design of secure urban spaces. By highlighting the limitations of relying exclusively on subjective expert evaluations, the study advocates for an evidence-based design approach where numerical modeling validates and refines expert intuition. The identified indicators can be directly incorporated into design guidelines for critical infrastructure, governmental buildings, and high-risk urban zones, thereby enhancing resilience against explosive threats. Furthermore, the study contributes to the broader discourse on passive defense, bridging architectural design with urban crisis management.

Conclusion
The comparative analysis revealed that flat and compact forms, contrary to expert assumptions, exhibit superior blast resistance due to reduced exposed surface areas. At the same time, irregularities in plan and façade remain critical weaknesses that exacerbate vulnerability. The combined use of AHP and finite element modeling not only enhanced the robustness of the findings but also introduced a replicable methodology for future studies. This research thus establishes a methodological and conceptual foundation for integrating architectural form into the broader framework of blast-resistant and resilient urban design.