This video is very informative. As a Civil Structural Engineering student, It really showed what I've learned and people actually use those methods to design the structure. Thank you!
This is a fantastic video to show to non-engineering people to explain what structural engineers do! I always have trouble explaining what engineers do to "lay-people" without rambling for an hour.
The most important part in all this process is the drawing part. It really does reflect all the info you got out from the design and in some extent, it can provide some insight and make you cuestion if you are designing something good or bad.
@@BigDripper1of1 all the considerations you took in the analysis and design of the elements should be reflected in your drawing plans. For example, in a steel structure you consider that in your base plate, it will be a pinned support when designing it on whatever application you use for, but in your drawing plans you specify and draw it as a moment connection is something that can't happen in this case. One may think that's impossible to make such mistakes, but in reality that's the hardest task of being an engineer.
Very true! If our designs don't make it on the drawings correctly, they will be constructed wrong and our analysis goes to waste, not to mention the building may be built incorrectly with regards to the engineer's intent.
Thanks Mat, this is good. I am a technician for structural engineers (the drawing part in your video) and I was always curious about what they do before I am involved in the projects. this gives me the answer!
Great video. In practice, analysis and design is iterative and will happen at the same time as the drawings, especially because the architect and other folks need to coordinate their drawings with ours as their design developes.
As A Civil Engineering student at my 5th year, This 10 mins video about Structural engineering was more informative and constructive.. Thank you for those interesting informations .
This video tells us that structural engineering works in three fields Analysis, Design, and Drawing So it's better to learn each software from all those fields thanks mat for the wonderful video.
you're back collegue. in my studio i play in background "structural engineering podcast". my collegue seriously think"ok....the boss is totally flip out". (in Italy, sadly english Is still a very foreing lenguage). but step by step, they love this "podcast time". now.... thumbs up and see de video. see you later
Hey Mat! I'm a Structural Engineer on Brazil, do you know if it's possible or common to work remotely for a company overseas? If so, could you please make a video telling how does it work? Tyy
It's possible but I think it's more common for very large companies that have international offices. I don't know too much on that subject though, as I'm sure there's visa issues and what not. Might be easier to work as a contractor though, thinking of something like Fiverr.
Only thing I see missing is submittal reviews. For example, reviewing concrete mix design prior to concrete being ordered, or reviewing rebar shop drawings as the structural drawings don’t go into that crazy level of detail that shops do.
Sir, I just have a question that I hope you will notice,,, that I am just curious because of the tall buildings that reach 50 storeys above, how do the first floor pole of the building handle the 50 storey building above, , because the pole of the first floor carried all the weight of the building,,,
Thanks, I was wondering last night, what if it was a residential block and ALL the tenants place their heaviest loads on one corner of the building and left the other side empty. Won't it eventually slant and break if left for long periods?
Hi. I'm a Civil Engineering student. I was asking which software you were using to analyze the stress area in your building when exposed to lateral loads or gravitational loads on your slabs etc
@@MatPicardal you can write your own programs or develop your own software for analysis and design Code stipulates you design for the most critical of 1 Gravity loads alone 2 Gravity + Wind loads 3 Gravity + Earthquake loads
wow, this is great and pretty new in YT! Can you talk, someday, about curved structures, like concrete shells? Because i think my formation lacks this type of thing. And how engineers (or what type of) study something like this
I'm curious to know what is included in an architect formation in the USA, I don't know if it is the same but the 1st phase of analysis that you mention doesn't work like that here in Italy! As an architecture student we are tought to design (roughly or so) the structure, even using structural engineering softwares like SAP, and THEN you go to an engineer to properly define the job. In this way you can keep everything under control, given that you won't have to apply massive changes for unespected issues. In the USA the architects don't have the structural responsability of a project and that's why or they simply "don't want to risk it"? Thanks whoever will answer!!
This is what architectural engineering is all about. It doesn't cover the nitty gritty of structural engineering The structural engineer has the final say on the safety and stability of the structure, not the architect or architectural engineer
@@festusajayi8917 so there's also another profession, I didn't know! I'll have to search what my course of studies translates into in the USA, seeing that it's like in the middle. Thank you for your answer!
It would be interesting to see more stats, like how much a upper floor weighs (with average square footage), so we can see how much the base can hold. I don't think total weight is supported by elevator / stair shaft which is all you provided. How does all the weight get dispersed at the base? There is no great explanation on UA-cam.
How do you know that the ground isn't going to shift and the foundation isn't going fail? I've seen homes on the side of hills but how do you know the ground isn't going to shift and there will be a landslide? This is always my main concern. For buildings not on hills how can you guarantee that the ground is solid enough?
That’s a geo technical problem, the site would already be analysed by geotechnical engineers to get the bearing capacity and see whether the soil fill needs to be change and so on and so forth. Not a structural problem
I hope u can make a video for tips and tricks for reinforced concrete design and steel and timber design. Cause these 2, I'll be taking this coming 2nd semester hahahaha. Btw happy new year engineer!
You can start by refreshing what you know about strength of materials, statics and the courses of structural analysis. But I'll tell you to focus more on the part of strength of materials than anything else, it's very important to know this because all the theory used on explaining those 3 materials, uses a lot of information from strength of materials sometimes. Also try to always imagine or illustrate the situations when you begin the course, it helps a lot than just seeing a bunch of numbers and equations.
So when and where have you "experts" discussed the distribution of steel down the North Tower of the Twins. What were the tons of steel and tons of concrete on each level?
As Structural Engineer of many years experience (qualified before you were born I guess), I would point out that there's a conceptual phase way before the analysis phase. The ultimate success of the project is probably decided at this stage - have a good structural concept and it will be easy to design and build, have a bad concept and it will be a struggle until the end of the project. It's a big mistake to get involved in the analysis too early in the project cycle.
Quite right The conceptual phase can also be referred to as a feasibility study phase or preliminary design phase Check lists for analysis and design can be handy in this phase
@@festusajayi8917 The conventional sequence and terminology in some engineering sectors is feasibility studies / conceptual design / FEED (front end engineering design) / detailed design.
Sir i am completing bsc in civil Engineering. So what would be best.structure designer or a project engineer. How long it takes to learn designing. Etabs,sapp,or how many app need.i am confused actually what to do.i really love mechnics of something. Is there any opportunity for me after my graduation for msc in usa.if there is then what's the process. Listening you From Bangladesh 🇧🇩🇧🇩..
For high rises in seismic zones, you can see steel braces being used as outriggers/support for the concrete cores. But usually not combined for most convential projects as it's generally more expensive to construct.
How commonly are you actually doing work by hand? I work for a Gc and find that after talking to most of the structural engineers, I’m doing more math than them just with takeoffs and basic form forces than they do in design. They’ve always told me they just use the computer
It depends what they are using to do the analysis. Some programs require the engineer to calc their own loads. Column and foundation loads are almost always hand calced. Quick design checks during CA are also often done by hand. It's all simple math.
My brother you should have been there when certain engineers built certain multistory buildings with supporting beam structure so low quality that they melted from a fuel fire
First rule Foundation, second rule foundation, third and final rule foundation PERIOD!! The problem with nearly all designs is 1. Corruption. i.e. bribes, use of different materials by the builders/contractors, cutting corners. etc etc. 2. Miscommunication. 3. What's designed is rarely if ever translated to a build i.e. last minute changes, additions, subtractions etc etc. 4. Costs are ever increasing. 5. Last but not least is poor or incorrect design. Overcome all of the above and the build might be completed to everyones satisfaction. But until then we will get more Surfsides.
How to meet the code for Americans with disabilities act of 1990, 504 section of rehabilitation Act of 1973, architecture barrier act of 1968 and fair housing Act?
Cool video can i have a favor can we get you as our respondent for our thesis can we interview you. Our topic si Earthquake proof we just need someone who are have the knowledge in earthquake proofing thank you ❤️
Very nice. How are engineers in the US deal with a risk of disproportional collapse? Here in the EU it can be tricky for the high-risk category buildings, because eurocodes give no direct guidance and require to do it well anyway.
Some high profile buildings require redundancy and alternate load paths, such as if one column fails, the other nearby columns can take the load. I have limited experience on it, but that's what I've seen done.
I recall a question a principal at a structural firm in Lagos Nigeria asked me. The moron spent more time trying to understand how I did the calculation than the duration of the interview.
ŻEBY, WSZYSCY Z EUROPY BY BUDOWALI W TYM SYSTEMIE JAK PAN PRZESTAWIŁ NA WIDEO, TO BY NIE BYŁO ŻADNYCH PROBLEMÓW CO DO ZABESPIECZONY DOMÓW PRZEZ TRZĘSIENIE, CZY WICHURĄ. DZIĘKUJĘ SERDECZNIE.
The structural engineer... By a lot too. Architects have to study for much longer, do several years of low-paying internships, and pass multiple examinations before they qualify for licensure, and they don't make shit in the end. - Sincerely, an aspiring architect.
the Kingdom of GOD is coming…“Silver is for the kettle, and gold for the furnace, but The LORD is the tester of hearts- Proverbs 17:3” your heart is like discovered silver, dirty and not pure, when silver is purified it is melted over and over, to the point that when it’s melted and glows red hot, it is pure enough to see your own reflection in the puddle, so also does the LORD purify your heart, till HE can see HIS own reflection in it, seek the LORD and be reborn, ask The LORD to renew and restore you, repent and be baptized for the forgiveness of sins, Jesus died so that our sins will be wiped away and so that we could be made new, if would be wise you would be wise for yourself, pick up your cross and deny your flesh and follow the path of GOD, for The you Kingdom of GOD is at hand, in JESUS MIGHTY NAME Amen and Amen
This video is very informative. As a Civil Structural Engineering student, It really showed what I've learned and people actually use those methods to design the structure. Thank you!
Thanks for the comment Aden! Glad it helps.
best video ever, I am in my 5th year as a Civil Engineering student and this video could have come in handy in my early years. good video 😄😄😄👍👍
Glad you enjoyed it! Best of luck!
THANK you for your videos
I would like to become a structural engineering but i dont know what school To go
@@MatPicardal hello could you referme a school where i can go To learn to be a structural enginer please
@@MatPicardal I learn civil engineering in my country but i would love to come To us to study
This is a fantastic video to show to non-engineering people to explain what structural engineers do! I always have trouble explaining what engineers do to "lay-people" without rambling for an hour.
Amazing, i'm gonna be studying architecture in the fall so this is all very important for me to learn early.
The most important part in all this process is the drawing part. It really does reflect all the info you got out from the design and in some extent, it can provide some insight and make you cuestion if you are designing something good or bad.
How do you define important
@@BigDripper1of1 all the considerations you took in the analysis and design of the elements should be reflected in your drawing plans. For example, in a steel structure you consider that in your base plate, it will be a pinned support when designing it on whatever application you use for, but in your drawing plans you specify and draw it as a moment connection is something that can't happen in this case. One may think that's impossible to make such mistakes, but in reality that's the hardest task of being an engineer.
Very true! If our designs don't make it on the drawings correctly, they will be constructed wrong and our analysis goes to waste, not to mention the building may be built incorrectly with regards to the engineer's intent.
Thanks Mat, this is good. I am a technician for structural engineers (the drawing part in your video) and I was always curious about what they do before I am involved in the projects. this gives me the answer!
Zoe, glad it was helpful!
The best video I've seen. It's amazing how clearly you explain it all. Thank you, Mat!
Great video. In practice, analysis and design is iterative and will happen at the same time as the drawings, especially because the architect and other folks need to coordinate their drawings with ours as their design developes.
Thank you Mat, would appreciate that you can keep on continuing on releasing the technical video like this.
More to come!
As A Civil Engineering student at my 5th year, This 10 mins video about Structural engineering was more informative and constructive..
Thank you for those interesting informations .
Another excellent video! Nice work, Mat.
Bookmarking this one to show to my friends what structural engineering is all about.
Thanks Alex, hope you're doing well and Happy New Year!
Thanks for representing us here on UA-cam, Mat!
Thank you for this video. Very informative and helpful for those with anxiety about staying in tall buildings
Useful video with clear explanation which was easy for to understand. Any videos about how the wind load is performed..?
Thanks a lot for explaining the structural design workflow in awesome way 😃
Great video, Mat. I appreciate the quality content and great explanations. Keep up the awesome videos!
This video tells us that structural engineering works in three fields Analysis, Design, and Drawing So it's better to learn each software from all those fields thanks mat for the wonderful video.
Great job - as always Mat
Thanks again Jared!
I do prefer the buildings that don't fall down, so thank you, structural engineers.
Hello mat
How to fix failure construction house?
If it impossible, how to dissamble 2nd floor house with manual technique?
you're back collegue. in my studio i play in background "structural engineering podcast".
my collegue seriously think"ok....the boss is totally flip out". (in Italy, sadly english Is still a very foreing lenguage). but step by step, they love this "podcast time". now.... thumbs up and see de video. see you later
Thanks Paolo, yes, it's tough with work and balancing health and relationships, but I eventually make time!
This video was absolutely amazing to watch. I learned a lot, thanks Mat!
i was in a parking garage under a building today and was wondering how everything stood up! thank you!
This is really incredible. Thank you so much and please try to give us, this type of video.
Great job Matt. Good to see you doing well.
Great video, Mat!
Good information sir,, 😊👍
Hey Mat! I'm a Structural Engineer on Brazil, do you know if it's possible or common to work remotely for a company overseas? If so, could you please make a video telling how does it work? Tyy
It's possible but I think it's more common for very large companies that have international offices. I don't know too much on that subject though, as I'm sure there's visa issues and what not. Might be easier to work as a contractor though, thinking of something like Fiverr.
Thank you sir. Keep making these type of videos about teaching aspects of construction.
In 7:07 , it’s mentioned loads will be transferred from slab to column (is it assumed that slab and beams are monolithically casted?)
In design of Flat Slab no drop beam. The load transfer from slab to column
I consider the word "slab" here as "floor", the vertical load spreading the tributory area is transferred to the column,
Yup, it's a two-way flat plate slab (no beams, slab is strong enough to transfer loads to the columns).
@@MatPicardal What is depicted in the video is a flat slab as distinct from a two way slab which is supported by beams on its 4 sides
What is the official name of that building frame model @ 3:13? I always saw them but could never remember their name.
Mola Model. I made more videos demonstrating it with a discount link as well: ua-cam.com/video/141Zmuw9Xcg/v-deo.html
very clear and informative. Thank you for presenting this video.
Glad it was helpful!
Excellent Presentation!
Amazing video!
Thanks!
Wow, thank you for making and sharing this video, it's very helpful and informative.
Thank you, really interesting and useful for work
Great content ❤
Thanks Jamil!
Only thing I see missing is submittal reviews. For example, reviewing concrete mix design prior to concrete being ordered, or reviewing rebar shop drawings as the structural drawings don’t go into that crazy level of detail that shops do.
Uniqe video as usual keep it 💕up
Sir, I just have a question that I hope you will notice,,, that I am just curious because of the tall buildings that reach 50 storeys above, how do the first floor pole of the building handle the 50 storey building above, , because the pole of the first floor carried all the weight of the building,,,
Thanks, I was wondering last night, what if it was a residential block and ALL the tenants place their heaviest loads on one corner of the building and left the other side empty. Won't it eventually slant and break if left for long periods?
Hi. I'm a Civil Engineering student. I was asking which software you were using to analyze the stress area in your building when exposed to lateral loads or gravitational loads on your slabs etc
ETABS for lateral loads, and RAM Concept for gravity. Other alternatives include RISA 3D and ADAPT.
@@MatPicardal you can write your own programs or develop your own software for analysis and design
Code stipulates you design for the most critical of
1 Gravity loads alone
2 Gravity + Wind loads
3 Gravity + Earthquake loads
wow, this is great and pretty new in YT! Can you talk, someday, about curved structures, like concrete shells? Because i think my formation lacks this type of thing. And how engineers (or what type of) study something like this
Sir, what do you think about the buildings thats collapse on turkey earthquake ?
this video is really cool
waiting for more sir
I'm curious to know what is included in an architect formation in the USA, I don't know if it is the same but the 1st phase of analysis that you mention doesn't work like that here in Italy! As an architecture student we are tought to design (roughly or so) the structure, even using structural engineering softwares like SAP, and THEN you go to an engineer to properly define the job. In this way you can keep everything under control, given that you won't have to apply massive changes for unespected issues. In the USA the architects don't have the structural responsability of a project and that's why or they simply "don't want to risk it"? Thanks whoever will answer!!
This is what architectural engineering is all about.
It doesn't cover the nitty gritty of structural engineering
The structural engineer has the final say on the safety and stability of the structure, not the architect or architectural engineer
@@festusajayi8917 so there's also another profession, I didn't know! I'll have to search what my course of studies translates into in the USA, seeing that it's like in the middle. Thank you for your answer!
This video answer my confusing Sir. Please can you make one for bridge for me. thank you, very informative video, and educational.
It would be interesting to see more stats, like how much a upper floor weighs (with average square footage), so we can see how much the base can hold.
I don't think total weight is supported by elevator / stair shaft which is all you provided.
How does all the weight get dispersed at the base?
There is no great explanation on UA-cam.
Can you please make a video about buildings that combine Steel sections with Concrete
Hi Mat, I think you forget the give and take between drafters and engineers during documentation and modelling.
i suggest a video series for English terminologies for fhe field of construction for foreign structural engineers
Hello Mat, nice an clear video, tell me what structural software do you use for analisis?, like the showing in the video
How do you know that the ground isn't going to shift and the foundation isn't going fail? I've seen homes on the side of hills but how do you know the ground isn't going to shift and there will be a landslide? This is always my main concern. For buildings not on hills how can you guarantee that the ground is solid enough?
That’s a geo technical problem, the site would already be analysed by geotechnical engineers to get the bearing capacity and see whether the soil fill needs to be change and so on and so forth.
Not a structural problem
where to make structural analysis building with earthquake demper system?
Sir, can you please make a video about FRP/Fiber Reinforced Polymer as a material used in construction? Thankyou
great video air I really appreciate your work
Master the concepts of practical civil engineering here ✌
Sir, which structural analysis software is often used for you?
I hope u can make a video for tips and tricks for reinforced concrete design and steel and timber design. Cause these 2, I'll be taking this coming 2nd semester hahahaha. Btw happy new year engineer!
You can start by refreshing what you know about strength of materials, statics and the courses of structural analysis. But I'll tell you to focus more on the part of strength of materials than anything else, it's very important to know this because all the theory used on explaining those 3 materials, uses a lot of information from strength of materials sometimes. Also try to always imagine or illustrate the situations when you begin the course, it helps a lot than just seeing a bunch of numbers and equations.
Thanks Miggy, been thinking about those!
4:30 in the case of seismic areas, the core building wall would be enough to resist an earthquake lateral force? BTW great channel. Just subscribed!
what is the best software in analyzing a building?
What causes the cracks around RC beam hollow areas
Excellent information
Hey Mat, which software you use for your analysis?
Thankyou Sir
What software you recommend/use for structural engineering load estimation & simulations
which software do you use?
Good day Engr. Paano ba maging isang licensed structural engineer dto sa pilipinas?
do you have any courses so that I can take it on undemy?
So when and where have you "experts" discussed the distribution of steel down the North Tower of the Twins. What were the tons of steel and tons of concrete on each level?
Love your videos ❤️❤️
As Structural Engineer of many years experience (qualified before you were born I guess), I would point out that there's a conceptual phase way before the analysis phase. The ultimate success of the project is probably decided at this stage - have a good structural concept and it will be easy to design and build, have a bad concept and it will be a struggle until the end of the project. It's a big mistake to get involved in the analysis too early in the project cycle.
yes, I think he started with schematic phase directly in this video.
@@DeepakKrishna11 He skipped over the conceptual phase which is typical for young engineers. Too keen to resort to their computers
Quite right
The conceptual phase can also be referred to as a feasibility study phase or preliminary design phase
Check lists for analysis and design can be handy in this phase
Agreed. Feasibility is everything
@@festusajayi8917 The conventional sequence and terminology in some engineering sectors is feasibility studies / conceptual design / FEED (front end engineering design) / detailed design.
Best video engineer
Hi Mat,
I want to know that which software have you been using for showing stress generation chart over the building plan?
Please answer my query
Hey sir I think the loads from the slabs will be transfered to the beams first before into the columns? But anyway good explanation 👌🏻
No beams with flat plate
sir, big fan ❤🇧🇩
Sir i am completing bsc in civil Engineering. So what would be best.structure designer or a project engineer.
How long it takes to learn designing. Etabs,sapp,or how many app need.i am confused actually what to do.i really love mechnics of something. Is there any opportunity for me after my graduation for msc in usa.if there is then what's the process.
Listening you From Bangladesh 🇧🇩🇧🇩..
Can you put braces in rcc buildings?
Everything is possible. But from where I am, it's not common
It's more common in steel structures
@@symonortega thanks
@@Joker-oh3lb there are some examples in Google images if you want more insight
For high rises in seismic zones, you can see steel braces being used as outriggers/support for the concrete cores. But usually not combined for most convential projects as it's generally more expensive to construct.
@@MatPicardal interesting
What about foundation and soil analysis?
It is done by geotechnical engineer.
Thanks
How commonly are you actually doing work by hand? I work for a Gc and find that after talking to most of the structural engineers, I’m doing more math than them just with takeoffs and basic form forces than they do in design. They’ve always told me they just use the computer
It depends what they are using to do the analysis. Some programs require the engineer to calc their own loads. Column and foundation loads are almost always hand calced. Quick design checks during CA are also often done by hand. It's all simple math.
thanks sir
My brother you should have been there when certain engineers built certain multistory buildings with supporting beam structure so low quality that they melted from a fuel fire
First rule Foundation, second rule foundation, third and final rule foundation PERIOD!!
The problem with nearly all designs is 1. Corruption. i.e. bribes, use of different materials by the builders/contractors, cutting corners. etc etc. 2. Miscommunication. 3. What's designed is rarely if ever translated to a build i.e. last minute changes, additions, subtractions etc etc. 4. Costs are ever increasing. 5. Last but not least is poor or incorrect design.
Overcome all of the above and the build might be completed to everyones satisfaction. But until then we will get more Surfsides.
What is the go to software, you civil engineers use??
There's a lot out there, but ETABS, RISA, RAM Concept, ADAPT, Enercalc, SPColumn are just a few.
Good bro
How to meet the code for Americans with disabilities act of 1990, 504 section of rehabilitation Act of 1973, architecture barrier act of 1968 and fair housing Act?
Basic info but OK! For students
Cool video can i have a favor can we get you as our respondent for our thesis can we interview you. Our topic si Earthquake proof we just need someone who are have the knowledge in earthquake proofing thank you ❤️
Do structural engineers need to take dynamics?
Except WTC7 xD
HNY Mat
Very nice. How are engineers in the US deal with a risk of disproportional collapse? Here in the EU it can be tricky for the high-risk category buildings, because eurocodes give no direct guidance and require to do it well anyway.
Some high profile buildings require redundancy and alternate load paths, such as if one column fails, the other nearby columns can take the load. I have limited experience on it, but that's what I've seen done.
Great
Not as simple and straight forward as he puts it
Before the advent of computers, analysis and design was undertaken manually
I recall a question a principal at a structural firm in Lagos Nigeria asked me. The moron spent more time trying to understand how I did the calculation than the duration of the interview.
You can be good in teaching.
Thank you Thor!
ŻEBY, WSZYSCY Z EUROPY BY BUDOWALI W TYM SYSTEMIE JAK PAN PRZESTAWIŁ NA WIDEO, TO BY NIE BYŁO ŻADNYCH PROBLEMÓW CO DO ZABESPIECZONY DOMÓW PRZEZ TRZĘSIENIE, CZY WICHURĄ. DZIĘKUJĘ SERDECZNIE.
Structure engineering vs architecture who is earn more money
The structural engineer... By a lot too. Architects have to study for much longer, do several years of low-paying internships, and pass multiple examinations before they qualify for licensure, and they don't make shit in the end. - Sincerely, an aspiring architect.
Can you make a video about shish kebab steps, please. Thanks
Everyone in the comments is an engineer, I’m just a stoner 😂
the Kingdom of GOD is coming…“Silver is for the kettle, and gold for the furnace, but The LORD is the tester of hearts- Proverbs 17:3” your heart is like discovered silver, dirty and not pure, when silver is purified it is melted over and over, to the point that when it’s melted and glows red hot, it is pure enough to see your own reflection in the puddle, so also does the LORD purify your heart, till HE can see HIS own reflection in it, seek the LORD and be reborn, ask The LORD to renew and restore you, repent and be baptized for the forgiveness of sins, Jesus died so that our sins will be wiped away and so that we could be made new, if would be wise you would be wise for yourself, pick up your cross and deny your flesh and follow the path of GOD, for The you Kingdom of GOD is at hand, in JESUS MIGHTY NAME Amen and Amen
@@juanit0tackit0tackito2 Jesus got murdered for being a dickhead, why would I follow that guy?
Dude same hahaha