Very tall buildings have distinctive fire safety design issues that are not experienced in different forms of buildings. For instance, because the peak of the structure is beyond the reach of ladders, tall buildings are equipped with more fire security options as it is not attainable for the fire department to provoke exterior rescues from ladders and suppress fires with outside hose streams.
In regards to fire safety, the efficiency historical past of very tall buildings whereas very successful, has not been without catastrophic incidents. Many of those incidents have resulted in 1) quite a few deaths and accidents, 2) excessive property loss and 3) disruptions in business continuity. For example, the One Meridian Plaza high-rise hearth in Philadelphia that occurred in 1991 resulted within the lack of three firefighters and constructing by no means being re-opened. In 1988, the fireplace within the Interstate Bank Building in Los Angeles experienced one fatality and resulted within the building being out of use for six months.
Based on analysis and classes realized, the model building codes have made vital progress in addressing fireplace questions of safety in very tall buildings. At the same time, the complexity and distinctive challenges of today’s very tall buildings have created an setting where complete performance-based options have become a necessity.
To assist the design community with developing performance-based fire safety solutions for very tall buildings, in 2013, the Society of Fire Protection Engineers (SFPE) partnered with the International Code Council (ICC) to develop the Engineering Guide: Fire Safety in Very Tall Buildings.1 This publication is written as a guide to be used at the facet of native codes and standards and serves as an added tool to these involved within the fire protection design of distinctive tall buildings. The information focuses on design issues that affect the fireplace safety performance of tall buildings and how engineers can incorporate performance-based hearth protection by way of hazard and threat evaluation methodologies into the design of tall buildings. This article will talk about some of the unique hearth security design strategies/methodologies employed within the design of tall buildings which are referenced in the ICC/SFPE Guide.
Developing an efficient evacuation technique for a tall building is challenging as the time to complete a full constructing evacuation increases with constructing top. At the same time, above sure heights, the traditional method of requiring all occupants to simultaneous evacuate will not be practical as occupants turn into more susceptible to additional risks when evacuating via stairways. That is why tall buildings often employ non-traditional or alternative evacuation methods.
When designing an egress plan for a tall constructing, the first goal must be to offer an appropriate means to allow occupants to move to a spot of security. To accomplish this goal, there are a quantity of evacuation methodologies which are available to the design team. These evacuation strategies can include however are not restricted to 1) defend-in-place, 2) shifting folks to areas of refuge and 3) phased/progressive evacuation. It can also be possible that a combination of those strategies can be this greatest answer. When deciding on an acceptable technique, the design team should consider the required level of safety for the building occupants and the building performance aims that are identified by the building’s stakeholders.
Using protected elevators has become one other evacuation strategy that is becoming extra prevalent within the design of tall buildings. In addition to helping the fireplace department with operations and rescues, protected elevators at the second are being used for building evacuation, notably for occupants with disabilities. When considering elevators in an evacuation technique, there are a selection of design issues to suppose about: 1) security and reliability of the elevators, 2) coordination of elevator controls and building security systems, 3) education of building occupants and first responders and 4) communication to constructing occupants through the emergency.
Tall buildings typically employ non-traditional or different evacuation methods.
The penalties of partial or global collapse of tall buildings because of a severe hearth pose a big risk to a giant number of individuals, the fireplace service and surrounding buildings. At the identical time, tall buildings typically have distinctive design features whose role within the structure and fireplace response are not easily understood using conventional hearth protection strategies. These unique elements might warrant a must adopt a complicated structural fire engineering analysis to reveal that the building’s performance goals are met.
Performance-based design of structural hearth resistance entails three steps: (1) willpower of the thermal boundary conditions to a construction resulting from a fireplace; (2) calculation of the thermal response of the structure to the fireplace publicity, and (3) determination of the structural response of the structure. Guidance on performing this kind of evaluation could be found within the SFPE Engineering Standard on Calculating Fire Exposures to Structures2, and SFPE Engineering Standard on Calculation Methods to Predict the Thermal Performance of Structural and Fire Resistive Assemblies.3
Water-Based Fire Suppression Systems
In tall buildings, the water provide required for fireplace protection techniques may be greater than the aptitude of the public water provide. As such, fire safety system water supplies for sprinkler techniques and standpipes require the use of pumps and/or gravity water tanks to spice up the water stress. Reliability of this water supply is a key consideration. As such, redundant hearth pumps, gravity-based storage provides, or each may be needed to enhance system reliability.
Another problem to consider when designing water-based hearth suppression techniques is stress control as it’s attainable for system components to be exposed to pressures that exceed its maximum working stress. Consequently, it might be necessary to design vertical stress zones to manage pressures in the zone. Additionally, pressure regulating valves are sometimes needed. When installed, care have to be taken to make certain that these strain regulating valves are put in properly and adequately maintained.
Fire Alarm and Communication Systems
Providing constructing occupants with accurate information during emergencies increases their capacity to make applicable decisions about their very own security. Fire alarm and communication methods are an important supply of this info. Very tall buildings make use of voice communication systems which are integrated into the fireplace alarm system. When designing voice communication techniques you will want to ensure that the system provides dependable and credible information.
Fire alarm system survivability is another import factor to consider in fireplace alarm system design. For tall buildings, consideration ought to be given in order that an attack by a hearth in an evacuation zone doesn’t impair the voice messaging outside the zone. Some of the design considerations to attain survivability could embody: 1) safety of control equipment from fire, 2) protection of circuits. 3) configuration of circuits and 4) shielding of panels.
Tall buildings often make use of smoke management techniques that both vent, exhaust or limit the unfold of smoke.
Controlling the spread of smoke is extra difficult in tall buildings. For instance, tall buildings experience a phenomenon referred to as stack impact. Stack effect occurs when a tall constructing experiences a strain distinction throughout its height on account of temperature differentials between the skin air temperature and the within constructing temperature. This causes air to move vertically, depending on the skin air temperature – either upward or downward in a constructing. It can even cause smoke from a building fire to unfold throughout the building if not managed. That is why tall buildings typically make use of smoke management systems that either vent, exhaust or restrict the spread of smoke.
Other concerns in tall buildings included the air movement created by the piston impact of elevators and the results of wind. Air motion brought on by elevator automobiles ascending and descending in a shaft and the effects of wind can lead to smoke motion in tall buildings. These impacts turn out to be extra pronounced as the height of the building enhance.
Because very tall buildings complicate smoke unfold, effective smoke control is harder to achieve. The potential solutions are numerous and embrace a mix of active and passive options such as but not limited to: 1) smoke barrier partitions and flooring, 2) stairway pressurization methods, 3) pressurized zoned smoke management provided by the air-handling tools, and 4) smoke dampers. The answer applied into the design needs to deal with the constructing itself, its uses, related occupant characteristics and reliability.
First Service Issues
It goes without saying that tall buildings present unique challenges to the fireplace service. During the planning and design phases, it is necessary for the design team to work with the fireplace service to discuss the sort of resources that are wanted for an incident and the actions that will be wanted to mitigate an incident. This contains growing development and post-construction preplans. These preplans should include and not be limited to creating provisions for 1) fire service access together with transport to the highest level of the constructing, 2) establishing a water supply, 3) standpipe methods (temporary and permanent), 4) communication systems, and 5) understanding the operations of the fireplace safety methods within the constructing.
One of the challenges the fireplace service faces during incidents in tall buildings is the ability of firefighters to move gear to the incident location. Designers should bear in mind how the fireplace service can transport its tools from the response stage to the highest degree in a secure method.
Additionally, care needs to be taken when designing the fireplace command middle as it will present the fireplace service command workers with important details about the incident. The fire command heart must be accessible and may embody 1) controls for constructing techniques, 2) contact information for constructing management, 3) present buildings plans, 4) emergency response and egress plans and 5) preplans.
1 International Code Council/SFPE. (2013). ราคาเกจวัดแรงดัน : Fire Safety for Very Tall Buildings. Country Club Hills, IL.
2 SFPE. (2011). SFPE Standard S.01 2011, Engineering Standards on Calculating Fire Exposures to Structures. Gaithersburg, Maryland.
three SFPE. 2015). SFPE Standard S.02 2015, SFPE Engineering Standard on Calculation Methods to Predict the Thermal Performance of Structural and Fire Resistive Assemblies. Gaithersburg, Maryland.