Discussion: View Thread

  • 1.  The building is affected by the wind and earthquake at the same time.

    Posted 02-03-2020 10:54 AM
    Edited by Tirza Austin 02-03-2020 10:54 AM
    The building is affected by the wind and earthquake at the same time
    What is your suggestion for seismic rehabilitation target based on which functional segregation?

    Reza Mokarramaydenlou, Ph.D., C.Eng, P.E., S.E., M.ASCE
    Structural Engineering and Seismic rehabilitation Consultant 
    Mokarramandpartners LLC

  • 2.  RE: The building is affected by the wind and earthquake at the same time.

    Posted 02-09-2020 01:53 PM
    Dear Reza, it is an interesting question. But, what is the probability of occurrence of both situations at the same time? I prefer to use passive or semi-active control systems instead of seismic rehabilitation by itself. Semi-active control systems are well developed (i.e. https://ascelibrary.org/doi/10.1061/%28ASCE%290733-9445%282009%29135%3A4%28425%29 ) and are easy to install.

    Andres Guzman Ing., M.ASCE
    Associate Professor

  • 3.  RE: The building is affected by the wind and earthquake at the same time.

    Posted 02-10-2020 07:52 AM
    Edited by Tirza Austin 02-10-2020 08:00 AM
    No, It is unlikely that extreme events are concurrent.

    William Scott P.E., M.ASCE
    Scott Engineering
    Port Townsend WA

  • 4.  RE: The building is affected by the wind and earthquake at the same time.

    Posted 02-23-2024 04:19 PM

    I am late to the conversation but this has been a concern for a long time. 

    I had an engineer that figured rain water 1/2 full of water on seismic projects. I asked what would happen if and Earthquake happened during a rainstorm. He said what are the chances of that happening. There are aftershocks and aftershocks that happen for days surrounding earthquakes. 

    Hurricanes and earthquakes: Can one predict the other?

    January 9, 2018 at 12:00am

    When three major hurricanes and just as many powerful earthquakes happen at around the same time, as they did in 2017, many wonder if they are connected.

    Source: National Hurricane Center
    *Hurricane locations as of September 8, 2017, 2 a.m. EDT

    While the 2017 hurricanes and the earthquakes in Mexico are likely not connected, geophysicist Shimon Wdowinski believes there could be a correlation between hurricanes and the earthquakes that come much later. He is spearheading research supported by NASA examining whether powerful hurricanes can trigger earthquakes.

    Wdowinski developed the idea for the research project following the 2010 earthquake in Haiti. The magnitude 7 event destroyed much of Por-au-Prince and killed upwards of 300,000 people. Two years prior, four powerful hurricanes - Fay, Gustav, Hanna and Ike - dumped heavy rains on Haiti in just a matter of weeks, killing 800 people and devastating crops.

    In certain mountainous environments prone to both tropical cyclones and earthquakes, heavy rain - 3 to 9 feet of rain in a span of 3 to 5 days - can induce a large number of landslides. Over time, the landslide material is carried to the ocean resulting in significant erosion of the mountains and affecting the stress field within the Earth's crust. Wdowinski thinks this could trigger an earthquake. If he is right, an earthquake can occur several months to years after a wet cyclone strikes in an area.

    Haiti experiences limited seismic activity so Wdowinski is testing his hypothesis in Taiwan, where there is plenty of earthquake and cyclone data to examine.

    "We plan to provide convincing observations that will demonstrate the proposed cascading relations between wet tropical cyclones, landslides and earthquakes," Wdowinski said.

    He believes whatever results he gets will be applicable to the Caribbean and parts of South America. The data can also be applied to other similar tectonic environments affected by wet tropical cyclones including the Philippines where a magnitude 6.5 earthquake hit in July of 2017 - the same region devastated by Typhoon Haiyan in 2013.

    Although the delay of months and years between wet cyclones and earthquakes will make it difficult to translate results into a forecasting tool, Wdowinski hopes the data can be used to issue a general warning about possible future earthquakes.

    5.1-Magnitude Earthquake Strikes Ojai as Southern California Experiences Hurricane Hilary Tropical Storm

    Hurricanes and earthquakes: Can one predict the other?

    Tuesday's earthquake, which reached 5.9 (moderate) on the Richter scale, was just the beginning. This weekend, Hurricane Irene is predicted to make its way up the East Coast, hitting Maryland with winds surpassing 110 miles per hour. (2011)

    Daniel Duggan Aff.M.ASCE
    Seismic Business Development
    Saint Peters MO

  • 5.  RE: The building is affected by the wind and earthquake at the same time.

    Posted 02-26-2024 11:13 AM

    I had just entered practice when this thought first occurred to me, and I remember being alarmed and getting very curious.  I eventually concluded that this is not cause for concern.

    If we assume no correlation between wind and seismic (more on that later), the probability of a 700-year design wind concurrent with a 500-year design earthquake is on the order of one in 350,000 years.  If we turn it backwards and try to hit that 700-year MRI with a combined event, we're looking at a 25-year wind and a 25-year earthquake, which would never add up to a higher base shear than the independent design-level seismic or wind.

    I realize this National Hurricane Center information is suggesting that there is a correlation, but the text indicates that exceptionally large storms may cause earthquakes several months or years later.  These related demands would never hit a building simultaneously.  I sometimes think about the possibility of a building weakened by a disaster being destroyed by a subsequent aftershock or unrelated storm event weaker than the initial event, but in general, these buildings have already "failed" in the initial event and would not be protected by additional design consideration.

    Chapter 2 of ASCE 7 addresses many conditions of hazards coinciding. Section 2.3.1 says, "Wind and seismic loads need not be considered to act simultaneously."  By contrast, some load effects, such as soil pressure and thermal self-straining forces must be considered simultaneously with wind and seismic according to Chapter 2.  Live loads are considered simultaneously with LRFD lateral load, but in each combination including both, one or the other is prorated.  Similarly, wind-on-ice and rain-on-snow loads consider intersecting weather events that are correlated, and use lower recurrence intervals for the individual hazards calibrated to the contingent probabilities (i.e. the probability of one condition occurring given that the other occurs) to provide the same reliability.  This all tends to suggest that the standards development people have thoroughly considered this issue.

    Christian Parker P.E., M.ASCE
    Structural Project Engineer
    Chicago IL

  • 6.  RE: The building is affected by the wind and earthquake at the same time.

    Posted 02-26-2024 11:13 AM

    Dear Reza

    I suggest you check with the sub-committee. dealing with chapter.  I believe the seismic provisions are to provide the opportunity for occupants to exit the building after the earthquake, whether the building is any state to resist any further environmental event is not really considered.  So the question of probability of wind load (0.14 % annual probability) occurring when an accidental load (once in a lifetime) earthquake is too uneconomical to consider.

    However, your question may be best phased  what happens when a small earthquake occurs when a windstorm is occurring.  In that situation I would suggest you start with the deflected shape (and forces) from the windstorm and then apply a dynamic analysisto that deform shape. 

    David Thompson P.E., M.ASCE
    KTA Structural Engineers Ltd.
    Calgary AB