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I argue that the official story about the collapses of the Twin Towers and building 7 of the World Trade Center, according to which the collapses were caused by fire – combined, in the case of the Twin Towers, with the effects of the airplane impacts – cannot be true, for two major reasons. One reason is that fire has never, except allegedly three times on 9/11, caused the total collapse of steel-frame high-rise buildings. All (other) such collapses have been produced by the use of explosives in the procedure known as “controlled demolition.” The other major problem is that the collapses of all three buildings had at least 11 features that would be expected if, and only if, explosives had been used.

I also show the importance of the recently released of 9/11 Oral Histories recorded by the New York Fire Department. With regard to the Twin Towers, many of the firefighters and medical workers said they observed multiple explosions and other phenomena indicative of controlled demolition. With regard to building 7, many testimonies point to widespread foreknowledge that the building was going to collapse, and some of the testimonies contradict the official story that this anticipation of the building's collapse was based on objective indications. These testimonies further strengthen the already virtually conclusive case that all three buildings were brought down by explosives.

I conclude by calling on the New York Times, which got the 9/11 Oral Histories released, now to complete the task of revealing the truth about 9/11.

Nonlinear dynamic analyses are employed for seismic collapse risk evaluation of existing steel moment frame buildings. The standards, such as ASCE 41-17, often define collapse thresholds based on plastic deformations; however, the collapse process involves several factors, and plastic deformation is only one of them. An energy-based approach employs deformation and resistance responses simultaneously, so it can consider various factors such as excessive deformation, stiffness and resistance degradation, and low-cycle fatigue as cumulative damage for seismic assessment. In this paper, an efficient energy-based methodology is proposed to estimate the collapse threshold responses of steel moment frame buildings.

This methodology uses a new criterion based on the energy balance concept and computes the structural responses for different seismic hazard levels. Meanwhile, a pre-processing phase is introduced to find the records that lead to the collapse of buildings. Furthermore, the proposed methodology can detect failure-prone hinges with a straightforward probability-based definition.

The findings show that the proposed methodology can estimate reasonably accurate responses against the results of the past experiment on the collapse threshold. Based on past studies, ASCE 41-17 results differ from experimental results and are even overly conservative in some cases. The authors believe that the proposed methodology can improve it. In addition, the failure-prone hinges detected by the proposed methodology are similar to the predicted collapse mechanism of three mid-rise steel moment frame buildings.

In the proposed methodology, new definitions based on energy and probability are employed to find out the structural collapse threshold and failure-prone hinges. Also, comparing the proposed methodology results against the experimental outcomes shows that this methodology efficiently predicts the collapse threshold responses.

Studies showed that construction digitalisation could prevent or mitigate accidents rate on sites. Digitalisation applications may prevent or mitigate building project collapse (BPC) but with some encumbrances, especially in developing countries. There is a paucity of research on digital technologies application to prevent or mitigate BPC in Nigeria. Thus, the research aims to explore the perceived barriers that may hinder digital technologies from preventing or mitigating building collapse and recommend measures to improve technology applications during development.

The study is exploratory because of the unexplored approach. The researchers collected data from knowledgeable participants in digitalisation and building collapse in Nigeria. The research employed a phenomenology approach and analysed collected data via a thematic approach. The study achieved saturation at the 29th interviewee.

Findings show that lax construction digitalisation implementation, absence of regulatory framework, lax policy, unsafe fieldworkers' behaviours, absence of basic infrastructure, government attitude, hesitation to implement and high technology budget, especially in developing countries, are threats to curbing building collapse menace via digitalisation. The study identified technologies relevant to preventing or mitigating building collapse. Also, it proffered measures to prevent or mitigate building collapse via improved digital technology applications during development.

This research contributes to the construction digitalisation literature, especially in developing countries, and investigates the perceived barriers that may hinder digital technologies usage in preventing or mitigating building collapse in Nigeria.

Housing provision and the neighbourhood's safety are significant social sustainability concerns. If structural issues are not well checked, housing provision and the neighbourhood's safety may become threatened, especially in Lagos State, Nigeria. Thus, this study aims to investigate the perceived root cause of collapsed buildings at the construction stage using two case studies, its effect on social sustainability aspects and suggested measures to mitigate future happening and enhance achieving social sustainability aspects goals.

The researchers collected data from Nigeria's built environment experts and eyewitnesses/employees of selected cases of collapsed buildings. The study adopted a phenomenology type of qualitative research design and analysed collated data via thematic analysis and achieved saturation. The analysed data created three themes.

Results reveal that inadequate heavy equipment and personnel incapacitated relevant government agencies are responsible for handling emergency and rescue during building projects collapse. Preliminary findings show developers' greed and systematic failures as the root cause of Nigeria's building project collapse (BPC). It categorised the root causes into three groups (developer's related-cause, design team related-cause and government entities related-cause). The study suggested measures to mitigate future happening. The emerged measures were grouped into a penalty, regulatory, byelaw act, technical and safety measures.

This study contributes to curbing the threat to social sustainability of housing provision in cities. It reveals the underlying perceived root cause of collapsed buildings in Nigeria's building industry. Also, it suggested feasible measures to mitigate BPC. These measures may be modified and adopted by other developing countries facing similar challenges.

While anonymous online interactions could be helpful and less risky, they are usually not enough for LGBTQ+ people to satisfy the need of expressing their marginalized identity to networks of known ties (i.e. on identified social media like Facebook, WeChat, and TikTok). However, identified social media bring LGBTQ+ people both sources and challenges like “context collapse” that flattens diverse networks or audiences that are originally separated. Previous studies focus on LGBTQ+ people's disclosure and responses to context collapse, few studies investigate how their perceptions of context collapse are shaped and their privacy management beyond regulating disclosure on social media. Drawing on identity theory and communication privacy management (CPM), this study aims to investigate how the need of LGBTQ+ people for self-identity affects their perceived context collapse and results in privacy management on identified social media.

Given the target population is LGBTQ+ people, The authors recruited participants through active LGBTQ+ online communities, influential LGBTQ+ activists, and the snowballing sampling. The authors empirically examined the proposed model using the PLS-SEM technique with a valid sample of 232 respondents concerning their identity practices and privacy management on WeChat, a typical and popular identified social media in China.

The results suggested that the need for expressing the self and the need for maintaining continuity of self-identity have significant influences on perceived context collapse, but vary in directions. The perceived context collapse will motivate LGBTQ+ individuals to engage in privacy management to readjust rules on ownership, access, and extension. However, only ownership management helps them regain the perceived privacy control on social media.

This study incorporated and highlighted the influence of LGBTQ+ identity in shaping context collapse and online privacy management. This study contributes to the literature on privacy and information communication and yields practical implications, especially on improving privacy-related interactive design for identified social media services.

The study investigated the perceived causes of structural failure of public buildings, frequency of stability checks, stability checking procedures, measures to enhance public building stability checks and the roles of facility managers in the Accra Metropolis of Ghana.

Following a comprehensive literature review, the study employed a structured questionnaire survey and gathered the opinions of sixty-seven facility managers on the facility management practices. Following statistical pretesting of the dataset for reliability, distribution and agreement among the responses, the study analysed the dataset using mean scoring and weighted analysis.

The analysis showed that external building inspectors rarely inspect stability checks of the studied public buildings in Accra. It is also found that both reactive and proactive stability checking protocols are implemented in public buildings in Accra, but inadequate knowledge of facility managers limits technical stability checks. The study further revealed that stability checks of public buildings can be enhanced through incorporating site and location conditions into the design early upfront, active engagement of facility managers in the design and construction of public buildings, adequate budgetary provisioning for planned maintenance of public buildings, and encouraging appropriate use of public buildings.

This paper, to the best of the authors' knowledge, represents the first attempt to comprehensively examine the causes of structural failure of public buildings, frequency of stability checks, stability checking procedures, measures to enhance public building stability checks and the roles of facility managers in Ghana, from the perspective facility management.

The purpose of this paper is to present a probabilistic assessment and verify the effectiveness of seismic improvement schemes against earthquake, blast and progressive collapse. The probabilistic analysis is performed by taking into account the uncertainties in loading such as planar configuration and amplitude of the blast loading. A standard Monte Carlo (MC) simulation method is employed to generate various concepts of the uncertain parameters within the problem. For a given concept, various local dynamic analyses are performed within a certain range of distance, in order to quantify and locate the damage induced by impact wave on structural elements. In the next step, a limit state analysis is performed in order to investigate whether a progressive collapse mechanism forms under the acting loads or not.

( | ) and ( | ) are blast fragility and seismic fragility, respectively; ( ) and ( ) are annual occurrence rate of earthquake and blast, respectively. The purpose of the current study is to calculate for the primary structure as well as the retrofitted structure. Annual occurrence rate of earthquake can be calculated by using probability seismic hazard analysis for the site of interest, where the structure is located. In this paper, blast fragility and seismic fragility are defined rather differently; in other words, seismic fragility is defined as the probability of structural collapse given a specified level of seismic intensity whereas blast fragility is defined as the probability of collapse given that a significant blast event takes place. Both blast and earthquake loading conditions involve the activation of energy dissipation mechanism and, as a consequence, both can be resisted employing ductility enhancing techniques, such as column wrapping or jacketing and steel bracing.

The current paper aims to present a probabilistic assessment of progressive collapse under blast and earthquake loads. Non-dependent and incompatible events are considered to obtain a general rate of collapse. Finally, probabilistic collapse rate was obtained for a moment frame before and after modifying with convergent steel brace (CBF). The purpose of doing so is to investigate whether seismic improvement schemes can reduce collapse risk of different critical events or not.

Objective of the present work is to present a methodology for calculating the annual risk of collapse for a civil structure subjected to both seismic and blast loads, using a bi-hazard approach. Given that a blast event takes place, the probability of progressive collapse is calculated using a MC simulation procedure. The simulation procedure implements an efficient non-linear limit state analysis, formulated and solved as a linear programming problem. The probability of collapse caused by an earthquake event can be calculated by integrating the seismic fragility of the structure and the seismic hazard for the site.

This study aims to predict the volume changes and collapse potential (CP) associated with the changes in soil suction by using the pressure cell and the effect of initial load on soil suction. Three types of gypseous soils have been experimented in this study, sandy gypseous soil from different parts of Iraq. A series of collapse tests were carried out using the oedometer device [single oedometer test (SOT) and double oedometer test (DOT)]. In addition, large-scale model with soil dimensions 700 × 700 × 600 mm was used to show the effect of water content changes in different relations (collapse with time, stress with time, suction with time, etc.).

A series of collapse tests were carried out using the oedometer device (SOT and DOT). In addition, a large-scale model with soil dimensions 700 × 700 × 600 mm was used to show the effect of water content changes in different relations (collapse with time, stress with time, suction with time, etc.).

The CP increases with the increasing of the void ratio for each soil. For each soil, the CP decreased when the initial degree of saturation increased. Kerbala soil with gypsum content (30%) revealed collapse value higher than Tikrit soil with gypsum content (55%) under the same initial conditions of water content and density, this is because the higher the Cu value of Kerbala soil is, the more well-graded the soil will be. Upon wetting, the smaller particles or fractions of the well-graded soil tend to fill in the existing voids, resulting in a lower void ratio as compared to the poorly graded one. Consequently, soils with high Cu value tend to collapse more than poorly graded ones. The compressibility of the soil is low when loaded under unsaturated condition, the CP for samples tested in the DOTs under stress level 800 kPa are greater than those obtained from collapse test at a stress level of 200 kPa.

The initial value of suction for all soils increases with initial water content decreases.

The production of steel pipes with guaranteed external collapse pressure (e.g. high collapse casings for oil wells) requires the implementation of an accurate process control. To develop that process control it is necessary to investigate how different parameters affect the external collapse pressure of the pipes. Experimental/numerical techniques implemented to investigate the collapse behavior of steel pipes are presented. The discussion of the experimental techniques includes the description of the facilities for performing external pressure collapse tests and the description of an imperfections measuring system. The numerical techniques include 2D and 3D finite element models. The effects on the value of the pipes’ external collapse pressure of their shape, residual stresses and material properties are discussed.

The aim of this study is to ensure the structural integrity of 90° back-to-back (B2B) pipe bends by developing a closed-form numerical solution for estimating the collapse load of shape distorted 90° B2B pipe bends using non-linear finite element (FE) analysis.

The collapse behaviour of 90° B2B pipe bends with ovality (C_o) and thinning (C_t) has been evaluated by non-linear FE approach. Moment load is applied in the form of in-plane closing moment (IPCM). The current FE approach was evaluated by the numerical solution for the plastic collapse moment of pipe bends, which has been published in the literature. The collapse moments were obtained from the twice elastic slope (TES) method using the moment-rotation curve of every individual model.

The implication of C_t/C_th on collapse load is found to be highly insignificant in terms of increasing bend radius and C_o. C_o weakens the geometry, and its effect on the collapse load is substantial. A closed-form numerical solution has been proposed to calculate the collapse load of 90° B2B pipe bend with shape imperfections.

The implications of shape distortion (C_o and C_t) in the failure analysis (collapse load) of 90° B2B pipe bends has not been investigated and reported.